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  • General Chemistry  (890)
  • Cell & Developmental Biology  (372)
  • Biochemistry  (56)
  • Wiley-Blackwell  (1,318)
  • 1980-1984  (1,318)
  • 1970-1974
  • 1980  (1,318)
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Keywords
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  • 1980-1984  (1,318)
  • 1970-1974
Year
  • 1
    Electronic Resource
    Electronic Resource
    Masthead (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980) 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010101
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  • 2
    Electronic Resource
    Electronic Resource
    Tubulin nucleation and assembly in mitotic cells: Evidence for nucleic acids in kinetochores and centrosomes (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 1-15 
    Details
    ISSN: 0886-1544
    Keywords: centrosomes ; kinetochores ; microtubule initiation ; nuclease enzymes ; electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A lysed cell system was used to study the organelle structure and nucleation of exogenous tubulin at kinetochores and centrosomes in mitotic PtK2 cells. We have used this lysed cell system in conjunction with nuclease digestion experiments to determine which specific nucleic acids (DNA or RNA) are involved in either the structure and/or microtubule-initiating capacity of kinetochores and centrosomes. The results indicate that DNase I specifically decondenses the kinetochore plate structure, with the eventual loss in the ability of the chromosomes to nucleate microtubule assembly. DNase I had no effect on either the structure or nucleating capacity of centrosomes. Both RNase T1 and RNase A specifically attacked the amorphous pericentriolar material of the centrosomes, with a concomitant loss in the ability of this material to nucleate microtubule formation. Neither RNase appeared to affect the structure or nucleating capacity of the kinetochore. Therefore, the two types of nucleases appear to exert preferential effects on the different types of microtubule initiation sites in mitotic mammalian cells. The results suggest that DNA is a major component of the kinetochore, while RNA is a major component of the amorphous pericentriolar material. These findings support the concept that microtubule initiation sites in mitotic cells contain nucleic acids which are essential for the structural and functional integrity of the sites.
    Additional Material: 45 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010102
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  • 3
    Electronic Resource
    Electronic Resource
    Redistribution of actin and fascin in sea urchin eggs after fertilization (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 31-40 
    Details
    ISSN: 0886-1544
    Keywords: actin ; fascin ; actin cross-linking proteins ; fertilization ; microvilli ; sea urchin eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Following fertilization, the sea urchin egg cortex undergoes a structural change involving the assembly and organization of actin filaments into microvilli. Antifascin localizes this actin cross-linking protein in the microvilli of the fertilized egg cortex but no organized staining is present in the unfertilized cortex. Determination of the actin content of eggs using the DNAase I inhibition assay indicates that actin is about 1.4% of the total protein. Approximately 90% of this actin is soluble in low calcium isotonic extracts of unfertilized eggs while only 60-65% can be recovered in identical extracts of fertilized eggs. Similar measurements for fascin using a radioimmunoassay indicate this molecule represents about 0.3% of the total egg protein, essentially all of which is recovered in low calcium isotonic extracts of unfertilized eggs. After fertilization only 65-70% of this actin cross-linking protein is in the soluble phase. These results demonstrate a markedly different solubility for actin and fascin after fertilization, when the indirect immunofluorescence staining localizes fascin in the microvilli, and are consistent with the idea that fascin organizes newly polymerized actin filaments into the microvillar cores. A consideration of the amounts of actin and fascin incorporated into the cortex after fertilization and the number of microvilli on the egg surface indicates that the measured values are sufficient to account for the observed microvillar elongation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010104
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  • 4
    Electronic Resource
    Electronic Resource
    Control by calcium of the contractility of Labyrinthula slimeways and of the translocation of Labyrinthula cells (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 17-29 
    Details
    ISSN: 0886-1544
    Keywords: Ca-ion ; Labyrinthula ; contraction ; glycerination ; Ca-reservoir ; cell movement ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Colonies of Labyrinthula, a colonial marine protist, expand by protrusive movements of the specialized slimeways. The movements recorded in time-lapse films are of two types - filopodial and lamellipodial - and occur at rates equivalent to those of cell translocation.Evidence is presented that Ca2+ regulates the contraction of the actomyosin system of filaments present in the slimeways of Labyrinthula. In glycerinated models or in colonies exposed to ionophore A23187 contraction is evidenced by the occurrence of periodic contractions of the slimeways, giving them the appearance of strings of beads. Glycerinated slimeways contract on the addition of Ca2+ and ATP while slimeways provided with ionophore A23187 contract on addition of Ca2+ alone. The concentration required is 1.1 × 10-7 M Ca2+ while concentrations of 6.2 × 10-8 or lower were ineffective. Rates of contraction were measured in time-lapse films which provide evidence that contractions and beading occur everywhere in the slimeway system. When beading occurs, the 6-nm filaments transform from an array of parallel single filaments into an interwoven meshwork.We have identified by pyroantimonate-OsO4 fixation, as possible Ca2+ reservoirs, deposits of Ca2+ in bothrosomes - structures through which cell secretions pass into the slimeways. The electron-dense deposits are located at the base of the bothrosome and disappear after incubation with EGTA. We propose that the translocation of cells as well as the movements of slimeways may be regulated by the cells through the local measured liberation of Ca2+ from the bothrosome where it is sequestered.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010103
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  • 5
    Electronic Resource
    Electronic Resource
    An analysis of spindle ultrastructure during anaphase of micronuclear division in Tetrahymena (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 41-61 
    Details
    ISSN: 0886-1544
    Keywords: mitosis ; mitotic spindle ; kinetochore ; microtubule ; micronucleus ; Tetrahymena ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mitotic micronuclei were isolated from Tetrahymena thermophila and data on spindle ultrastructure were obtained from serial, transverse sections. Comparison of data from nuclei at meta- and early anaphase with data from nuclei at late anaphase showed that during anaphase, sister kinetochores move from the equator to the spindle poles, but kinetochore translocation occurs without any apparent change in either the number or length of kinetochore microtubules. This unprecedented result is ascribed significance with regard to the mechanism of kinetochore transport since there are only a limited number of ways that result could be achieved. The organization of the peripheral sheath changes during anaphase as evidenced by gaps in the sheath at late anaphase. Numerous kinetochore and non-kinetochore microtubules are located in polar regions of the spindle at late anaphase, whereas those regions contained only peripherally arranged microtubules at earlier stages. Tracking of individual kinetochore microtubules in late anaphase nuclei showed that some of them appeared to become incorporated into the peripheral sheath near the pole. At early and late anaphase, crossbridges connect adjacent microtubules throughout the spindle poleward to the kinetochores, as well as in the interzone.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010105
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  • 6
    Electronic Resource
    Electronic Resource
    Physarum myosin light chain binds calcium (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 63-71 
    Details
    ISSN: 0886-1544
    Keywords: Physarum polycephalum ; myosin light chains ; polyacrylamide gel electrophoresis ; calcium ; cytoplasmic streaming ; actomyosin ATPase regulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Myosin from the slime mold Physarum polycephalum contains three sizes of polypeptides: a heavy chain and two light chains, LC-1 and LC-2. Using a simple qualitative test for calcium binding by comparing electrophoretic migration of the polypeptides in sodium dodecy1 sulfate (SDS) acrylamide gels in the presence and absence of calcium, we have found that Physarum myosin light chain LC-2 migrates with an apparent molecular weight of 16,900 daltons in the presence of the metal ion chelator ethylene glycol bis (B-aminoethyl ether) N,N′-tetraacetic acid (EGTA). However, if calcium chloride is added to the sample prior to electrophoresis, the apparent molecular weight decreases to 16,100. Lanthanide and cadmium ions, but not magnesium, can substitute for calcium. Because the ionic radii of Ca2+, La3+, and Cd2+ are almost identical, we conclude that Physarum myosin LC-2 possesses a very size-specific binding site for calcium. Physarum myosin LC-1 and the heavy chain give no evidence for binding calcium by this test. Since cytoplasmic streaming in the plasmodium of Physarum requires calcium, our evidence indicates that the calcium-binding property of Physarum myosin LC-2 may be important in regulating the production of force by actomyosin in the ectoplasm. Unexpectedly, the myosin light chain in Physarum capable of binding calcium, LC-2, is the essential light chain, while LC-1 is a member of the regulatory class of myosin light chains [V. T. Nachmias, personal communication]. Until now, essential myosin light chains have not been shown to have high affinity divalent cation binding sites. This means a new version of the myosin-based model for actomyosin regulation by calcium may be required to explain cytoplasmic movement in Physarum, and perhaps in other motile systems involving cytoplasmic myosins as well.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010106
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  • 7
    Electronic Resource
    Electronic Resource
    The role of the extracellular matrix in cell motility in fibroblast aggregates (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 99-112 
    Details
    ISSN: 0886-1544
    Keywords: cell motility ; extracellular matrix ; collagen ; glycosaminogly cans ; collagenase ; hyaluronidase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of specific components of the extracellular matrix on the motility of tissue cells was studied using organ-cultured aggregates of embryonic fibroblasts. Spherical aggregates of chick embryo heart and skin fibroblasts were fused with [3H]-thymidine-labeled aggregates of the identical cell type. The movement of labeled cells into the unlabeled partner aggregate served as an estimate of cell motility in the cultured tissue-like aggregates. Collagenase treatment decreased the collagen content of heart fibroblast aggregates and increased cell motility; ascorbic acid treatment increased the collagen content of skin fibroblast aggregates and decreased cell motility. Reduction of the glycosaminoglycan content with testicular hyaluronidase had no measurable effect on cell motility in heart fibroblast aggregates.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010108
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  • 8
    Electronic Resource
    Electronic Resource
    Identification of genetic elements associated with muscle structure in the nematode caenorhabditis elegans (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 73-97 
    Details
    ISSN: 0886-1544
    Keywords: nematodes ; muscle structure ; mutants ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A search for new mutants with altered body-wall muscle cell structure has been undertaken in the nematode C elegans. One-hundred seventeen mutants were isolated after mutagenesis with ethyl methanesulfonate or ultraviolet light, enrichment by a motility-requiring test, and screening by polarized light microscopy; 102 of these mutants were in ten previously established genes, whereas 15 mutants permitted the identification of seven new complementation groups in C elegans. Two of the new genes map on linkage group I (unc-94 and unc-95) and four genes are sex linked (unc-96, unc-97, unc-98, and unc-99). One complementation group (unc-100) could not be mapped because of the special characteristics of its cohort mutants. Representative mutants of the mapped genes were examined by polarized light and electron microscopy. All of the mutants exhibit disruptions of the normal A and I band organization of thick and thin filaments. Several of the mutants produce collections of thin filament-like structures. In one of these cases, HE177 demonstrated collections of somewhat wider, intermediate-sized filaments as well, and the HE195 mutant produces paracrystalline aggregates of thin filaments amidst looser arrangements of similar structures. The mutants in newly identified genes, as well as the new mutants in previously established genetic loci, have promise as tools in the study of myofibrillar assembly and function. Among the 22 complementation groups associated with body-wall structure in C elegans, it is likely that some genes code for regulatory and morphogenetic functions in addition to the well-studied structural, contractile, and calcium-associated proteins in muscle.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010107
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  • 9
    Electronic Resource
    Electronic Resource
    Tubulin content and synthesis in differentiating drosophila cells in culture (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 113-129 
    Details
    ISSN: 0886-1544
    Keywords: tubulin ; Drosophila ; β-ecdysterne ; differentiating ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Drosophila Kc cells exposed to physiological doses of the moulting hormone, β-ecdysone, elongate, become motile, and subsequently aggregate. This pattern of morphogenesis was found to require the assembly of a microtubular cytoskeleton. Tubulin content was significantly increased in hormone-treated cells when compared to controls, as measured by a 3H-colchicine-binding assay. However, determinations of rates of tubulin synthesis and breakdown revealed no difference between control and hormone-treated cells for either parameter. When tubulin content was assayed by methods that do not depend on colchicine-binding activity, no difference between hormone-treated and control cells was observed. These results are discussed in terms of a model in which β-ecdysone affects the distribution of tubulin in “assembly-active” and “assembly-inactive” pools.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010109
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  • 10
    Electronic Resource
    Electronic Resource
    Meeting report (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 159-162 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010112
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  • 11
    Electronic Resource
    Electronic Resource
    The formation and elongation of filopodia during transformation of sea urchin coelomocytes (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 131-140 
    Details
    ISSN: 0886-1544
    Keywords: sea urchin coelomocytes ; motility ; filopodial formation and elongation ; ciné film analysis ; scanning electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sea urchin coelomocytes were examined during their morphological transformation from petaloid to filopodial forms by scanning electron microscopy and ciné film analysis. Petaloid coelomocytes have a variable morphology but, in general, consist of numerous thin sheets of cytoplasm, the petals, arranged in three dimensions around a central nuclear region. The transition to the filopodial form can occur in either substrate-attached or suspended cells and begins with the formation of several microspikes at the edge of each petal. These become more apparent as the cytoplasm between each microspike/filopodium is retracted centripetally. Concomitantly, the diameter of the flattened cell is increased by as much as twofold as the filopodia actively lengthen at a uniform, average rate of 0.5 μm/minute. The transformation process requires ca 15 minutes and is complete when the cell diameter no longer increases. These filopodia are functionally distinct from the passively produced retraction fibers observed in cultured mammalian cells. The formation of filopodia is biphasic and includes both a cytoplasmic retraction phase and an active extension phase.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010110
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  • 12
    Electronic Resource
    Electronic Resource
    Invited review: Guidance cue patterns and cell migration in muiticeliuiar organisms (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 141-157 
    Details
    ISSN: 0886-1544
    Keywords: axon guidance ; chemotaxis ; haptotaxis substrate pathways ; development ; pattern biology ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In multicellular organisms, guidance cues are either diffusible molecules or cellular or extracellular surfaces that are found in reproducible locations and that orient migrating cells and cell processes. The pattern of the guidance cues usually determines the complex in vivo migration routes of motile cells and cell processes. Within organisms, guidance cues are found to be organized in two general patterns: (a) broad gradients - such as diffuse chemotactic gradients; (b) discrete routes (substrate pathways) - such as chemotactic gradients confined to long channels, and such as the axon surface which represents a long specific highway for migrating Schwann cells.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010111
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  • 13
    Electronic Resource
    Electronic Resource
    Announcement (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 163-163 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010113
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  • 14
    Electronic Resource
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    Statement of purpose (1980)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 1 (1980), S. 167-167 
    Details
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970010114
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  • 15
    Electronic Resource
    Electronic Resource
    The changes in sperm nuclei after penetrating fish oocytes matured without germinal vesicle material in their cytoplasm (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 121-132 
    Details
    ISSN: 0148-7280
    Keywords: sperm nucleus ; fish oocyte ; germinal vesicle (GV) ; nuclear formation ; chromosome ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The processes occurring from sperm penetration to chromosome formation in the cytoplasm of Oocytes matured in vitro, after removal of the germinal vesicle (GV) and before hormonal stimulation, were observed with electron microscope. The dechorionated oocytes, matured without the participation of the GV material, responded to sperm penetration by initiating a cortical reaction within 20 seconds after insemination. The pentrating sperm nuclei transformed to male pronuclei with vesiculation of the nuclear membrane, chromatin decondensation, and formation of a pronuclear membrane. Before cleavage, however, no chromosome formation was observed in these oocytes. Instead, the fully grown pronuclei change to a picnotic chromatin mass without or with an only fragmented nuclear membrane, then disappeared. On the contrary, sperm nuclei that penetrated into the cytoplasm of naked eggs containing GV material during maturation underwent pronuclear and chromosomal formation. Judging from these observation in Oryzias oocytes, the GV material seems to be unnecessary for the formation of pronucleus from the compact sperm nucleus, but is essential for the process of chromosomal formation.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120030204
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  • 16
    Electronic Resource
    Electronic Resource
    Sertoli-germ cell interrelations: A review (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 179-202 
    Details
    ISSN: 0148-7280
    Keywords: Sertoli cell ; spermatogenesis ; junction ; germ cell ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120030209
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  • 17
    Electronic Resource
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    Masthead (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980) 
    Details
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120030301
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  • 18
    Electronic Resource
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    Actin filaments and mitochondrial movement in vertebrate spermiogenesis (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 203-209 
    Details
    ISSN: 0148-7280
    Keywords: actin ; mitochondrial movement ; spermiogenesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The presence of actin filaments around mitochondria during vertebrate spermiogenesis was demonstrated by immunofluorescence and immuno-electron microscopy and by heavy meromyosin decoration. The presence of actin is supposed to be related to mitochondrial rearrangements occurring in the spermatid stage.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120030302
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  • 19
    Electronic Resource
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    Role of cumulus cells for rat oocyte maturation and metabolism (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 133-140 
    Details
    ISSN: 0148-7280
    Keywords: rat oocytes ; maturation ; oxygen consumption ; cumulus cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Oocytes collected from immature PMSG-treated rats on the morning of proestrus were allowed to mature in culture either surrounded by their cumulus cells or after denudation. It was found that the time course of oocyte nuclear maturation was similar whether the cumulus cells were present or not. The oxygen consumption of noncultured oocytes was 0.12 nl/hr/oocyte and increased by 40% after four to eight hours in culture with intact cumulus. Respiration of oocytes cultured without cumulus remained constant throughout the culture, except for a transient decrease after four hours.It is concluted that the cumulus cells do not affect the spontaneous nuclear maturation in vitro, but that the metabolism in oocytes cultured with intact cumulus is different from that of cultured denuded oocytes. Furthermore, it appears that the rise in oocyte oxygen consumption is not a prerequisite for nucler maturation.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120030205
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  • 20
    Electronic Resource
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    Immunocytochemical studies on the zona pellucida of cow blastocysts (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 141-148 
    Details
    ISSN: 0148-7280
    Keywords: cow blastocysts ; zona pellucida ; stability and location of antigenic material ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Labeling of the zona pellucida of cow blastocysts with zona-specific anti-serum shows that antigenicity is unaffected by abnormal cleavage, in vitro culture, or frozen storage. The uniform labeling in thin sections indicates that the zona pellucida is homogeneous antigenically. Heavier labeling of the inner and outer surfaces of the zona pellucida in thick sections appers to be due to greater porosity of these regions, in which the zona material becomes highly dispersed, or even partly solubilized, thereby permitting the formation of an antigen-antibody matrix.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120030206
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  • 21
    Electronic Resource
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    Identification and hormonal control of reproductive-tract-specific antigens present in rabbit oviductal fluid (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 169-177 
    Details
    ISSN: 0148-7280
    Keywords: oviduct ; oviductal fluid ; mucin ; steroids ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Utilizing the intra-abdominal flask technique to collect oviductal fluid, the presence of two or possibly three reproductive-tract-specific antigens have been observed in rabbit oviductal fluid. Two of these antigens may be accounted for by the two forms of uteroglobin. The other antigen has a molecular weight greater than 200,000 daltons and its concentration in oviductal fluid is under hormonal control. During pseudopregnancy (PSP), when progesterone concentrations are high, or upon progesterone administration, the concentration of this high molecular weight antigen doubles in oviductal fluid. This correlates well with the previously observed increase in release of secretory products from the oviductal epithelia.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/mrd.1120030208
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  • 22
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    Ultrastructural studies of spermatogenesis in the anthocerotales. III. Gamete morphogenesis: From spermatogenous cell through midstage spermatid (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 149-167 
    Details
    ISSN: 0148-7280
    Keywords: Bryophyta ; Phaeoceros ; spermatid morphogenesis ; spermatogenesis ; ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An ultrastructural examination of spermatogenesis in Phaeoceros has shown nucleoli to be present in spermatogenous cells and to persist until the centrioles become associated with nuclei of young spermatids. At the onset of multilayered structure (MLS) formation, well-defined aggregations of osmiophilic strands begin to form in the nuclei of young spermatids and disappear shortly after chromatin condensation starts in the midstage spermatids. When the centrioles in the young spermatids are orientated perpendicular to the nuclear envelope, the nucleoplasm immediately in front of them is densely stained. Where the spline tubules of the MLS extend over the nucleus, the nuclear envelope is devoid of pores, and the inner nuclear membrane is contacted internally by the local deposition of dense staining nucleoplasm. Chromatin condensation begins with strands extending perpendicularly from the dense staining nucleoplasm beneath the spline and continues with the nuclear beak becoming filled with condensed chromatin. As the MLS lamellae disappear acropetally, the rear portion of the anterior mitochondrion (AM) extends back under the nuclear beak which now narrows to a size that approximates the anterior end of the nucleus of a spermatozoid. By the end of the mid-spermatid stage, the nucleus has coiled approximately one gyre of a helix and the five or six central slpine tubules extend over the plastid which is now located beneath the front end of the AM. Several profiles of endoplasmic reticulum confluent with the nuclear envelope are present. Possible factors which might play a role in determining the morphology of the mid-spermatids are discussed.
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    A new procedure for rapidly scoring acrosome reactions of human sperm (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 211-216 
    Details
    ISSN: 0148-7280
    Keywords: acrosome ; human sperm ; lectin ; capacitation ; fertilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Because the acrosome of human sperm is too small to be directly visualized by phase-contrast microscopy, acrosome reactions (that is loss of the acrosome) are generally not evaluated in studies of human sperm capacitation and fertilization. Nevertheless, it would be useful in such studies to have a technique for easily identifying and quantitating acrosome-reacted sperm. In this paper, we describe a method for labeling the human sperm acrosome with fluorescein-conjugated Ricinus communis agglutinin-60 (FITC-RCA); we show that in sperm without acrosomal caps, FITC-RCA labeling occurs either not at all or only in the equatorial segment of the acrosome. To determine if the absence of FITC-RCA labeling in the acrosomal cap region gives a reliable estimate of acrosome reactions, washed sperm or sperm incubated in a capacitating medium (BWW) were divided into two groups, which were then fixed for FITC-RCA labeling or transmission electron microscopy. Counts of acrosome reactions made by each method were similar, and we observed an increase in the percentage of reactions following incubation in BWW. We conclude that the FITC-TCA labeling technique is a reliable method for accurately scoring the percentage of acrosome-reacted human sperm.
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    Masthead (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980) 
    Details
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120030101
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    Effect of the inhibitors of ion movements, verapamil and tetraethylammonium, on fertilization of mouse eggs in vitro (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 1-7 
    Details
    ISSN: 0148-7280
    Keywords: mouse ; in vitro fertilization ; inhibitors of fertilization ; calcium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Better than 75% fertilization of C57BL/6 mouse eggs with C57BL/6 sperm is obtained in vitro in a modified Kreb's-Ringer-bicarbonate medium containing 8 mM HEPES. No fertilization of obtained when Ca2+ is omitted from this medium. The drug verapamil, which interferes with Ca2+ channels and blocks the acrosome reaction [Schackmann et al, 1978] and fertilization in the sea urchin, also blocks fertilization of mouse eggs in vitro when included in complete medium at a concentration of 80 μg/ml. Tetraethylammonium, which inhibits delayed axonal potassium currents and prevents the acrosome reaction in sea urchin sperm, also completely inhibits fertilization of mouse eggs in vitro at a concentration of 5 mM. Tetramethylammonium, which does not inhibit potassium movements at the same concentration reduces fertilization by about 50%. The data are consistent with the hypothesis that ion movements are necessary for activation of the sperm and/or egg in mouse fertilization.
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    Quantitation of avian spermatozoan motility: Neurochemical regulation (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 17-24 
    Details
    ISSN: 0148-7280
    Keywords: sperm ; motility ; neurochemical ; paraoxon ; acetylcholine ; cholinesterase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The hypothesis that motility of avian sperm is regulated by acetylcholine was examined by treating rooster (Gallus domesticus) sperm with choline analogs and paraoxon, an inhibitor of colonesterases. Acetylcholine chloride (AChCl) was most effective, acetylthiocholine iodide and butyrylthiocholine iodide were less effective, and choline chloride was ineffective in stimulating sperm motility. Histochemical localization of cholinesterase activity with the electron microscope showed enzyme activity to be associated with membranes of the head and within fibrillar components of the tail. Increasing concentrations of paraoxon decreased cholinesterase activity and increased sperm motility. The data provide evidence that the motility of avian sperm, like that of mammal and sea urchins, may be regulated in part by a system with similarities to the cholinergic neurotransmitter system.
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    Artificial fertilization of gametes from the South African clawed frog, Xenopus laevis (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 45-57 
    Details
    ISSN: 0148-7280
    Keywords: clawed frog ; egg ; fertilization ; jelly coat ; motility ; sperm ; Xenopus laevis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: A reproducible and effective method for fertilization eggs of Xenopus laevis was developed based of systematic manipulation of environmental factors. The effects of varying concentrations of individual components of a fertilization medium were tested by measuring jelly swelling, sperm motility, and sperm longevity. Results were used to develop an improved medium for fertilization, consisting of 41.25 mM NaCl, 1.25 mM KCl, 0.25 mM CaCl2, 0.0625 mM MgCl2, 0.5 mM Na2HPO4, 2.5 mM HEPES, 1.9 mM NaOH, final pH(2°) 7.8.
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    Initiation, prolongation, and reactivation of the motility of salmonid spermatozoa (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 247-257 
    Details
    ISSN: 0148-7280
    Keywords: spermatozoa (salmonid) ; adenosine triphosphate (ATP) in sperm motility ; cyclic adenosine monophosphate (cAMP) in sperm motility ; reactivation of trout sperm motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The motility of salmonid spermatozoa initiated by dilution of the milt with ovarian fluid or isotonic saline is brief duration; it was believed that it can be activated only once in the life of the spermatozoon. Dilution of the milt with an equal volume of isotonic saline (0.12 M-NaCl) containing 5 mM-3-isobutyl-1-methylxanthine (MIX) prolonged and intensified sperm motiliy. When motility had stopped after initial mobilization with saline or ovarian fluid, it could be reactivated by addition of MIX; reactivated spermatozoa fertilized eggs. Dilution with saline containing K+ (24 mEq/liter) did not initiate sperm motility even in the presence of MIX. The spermatozoa were mobilized by subsequent with 0.12 M-NaCl. The concentration of adenosine triphosphate (ATP) in sperm suspensions dropped on dilution with saline and rose as motility ceased, but declined without subsequent recovery following dilution with MIX-saline. The concentration of cyclic adenosine monophosphate (cAMP) rose and fell sharply on initiation of motility and rose again after motility had declined. While salmonid spermatozoa can be mobilized by dilition with saline alone, the effectiveness of MIX in reactivating “spent” spermatozoa supports the assumption that cAMP plays a role in the initiation of sperm motility.
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    Ovoperoxidase activity in ionophore treated mouse eggs. II. Evidence for the enzyme's role in hardening the zona pellucida (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 279-290 
    Details
    ISSN: 0148-7280
    Keywords: ovoperoxidase ; zona hardening ; zona pellucida ; mouse eggs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: One consequence of fertilization or parthenogenetic activation of mammalian eggs is an altaration in the solubility proprieties of the zona pellucida, known as zona hardening. Several lines of evidence indicate that an ovoperoxidase, which is activated and/or secreted from mouse eggs. Following parthenogenetic activation, corss-links tyrosine residues in the zona pellucida and results in hardening of the zona. First, zona hardening, as determined by decreased solubility of the zona in pronase, is inhibited by several compounds known to inhibit peroxidases. Inhibitors of hardening include phenylhydrazine, sodium sulfite, sodium azide, and glycine ethyl ester. Second, tyrosine analogs inhibit zona hardening, unless the phenolic hydroxyl group or ortho position is blocked. That is, O-methyltyrosine (methyl substitution of phenolic hydroxyl) does not inhibit hardening; o-methyltyrosine (methyl substitution of one ortho position) partially inhibits, whereas tyramine and N-acetyltyrosine (free hydroxyl and ortho positions) effectively block hardening. Finally, exogenous horseradish peroxidasepromotes limited hardening of the zona in unactivated eggs. These results are consistent with a peroxidase catalyzed cross-linking of tyrosines in the zona that results in hardening of the zona pellucida.
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    Fragmentation of condensed chromatin in nuclei of a plant sperm, pteridium aquilinum (L.) Kuhn (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 291-298 
    Details
    ISSN: 0148-7280
    Keywords: condensed chromatin ; sperm ; Pteridium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Nuclei of pteridium sperm have been dispersed by turbulence in natural or slightly alkaline buffer after stripping off the cytoplasm with nonionic detergent. The nuclei tended to break up into fragments arranged in a linear order. These fragments fluoresced brightly with acridine orange as did intact nuclei. Grounds are given for identifying the smaller fragments with chromosomes. It is proposed that the sperm nucleus of British Pteridium, possibly an autotetrapolid, consists of a sequence of paired homologues.
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    Announcement (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 307-307 
    Details
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1002/mrd.1120030315
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    The spermatozoon. Don W. Fawcet and J. Michael Bedford, eds. Urban and Schwarzenberg, Baltimore-Munich, 1979. 40 illustrted chapters. 441 pages. $49.00 (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 305-306 
    Details
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
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    URL: http://dx.doi.org/10.1002/mrd.1120030314
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    Partial activation of sea-urchin eggs by bonellin (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 309-316 
    Details
    ISSN: 0148-7280
    Keywords: fertilization ; membrane potential ; bonellin ; amino acid incorporation into proteins ; DNA synthesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We here describe further studies on the action of bonellin on sea-urchin eggs. Bonellin brings about Some of the changes that are known to occur in the egg upon fertilization. In particular, it appears to cause the increased rate of incorporation of amino acids into proteins, the increase of the voltage noise, and the exocytosis of some of the cortical granules. A comparison with the effect of ammonia is discussed.
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    Ultracytochemical localization of 3β-hydroxy-steroid ferricyanide reductase activity in the fetal mouse ovary (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 323-328 
    Details
    ISSN: 0148-7280
    Keywords: female meiosis ; estrogen synthesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: It has been suggested that the production of estrogens by the fetal ovary may modulate the entry or progression of meiosis in the female mammalian fetus. In the present study the possibility that the site of this steroid synthesis is the rete ovarii system was explored in the fetal mouse of gestational ages 12.5 to 18 days. The method of ultracytochemical localization of 3β hydroxy-steroid ferricyanide was used. Reaction product was found in the cytoplasm of the rete ovarii (prefollicular) cells as early as day 14 with increasing amounts seen at later gestational ages. The presence of this essential enzyme system in cells closely applied to oogonia and oocytes during an active meiotic period must be considered in developing concepts of meiotic entry.
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    Decondensation of sperm nuclei of australian marsupials: Effects of air drying and of calcium and magnesium (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 351-367 
    Details
    ISSN: 0148-7280
    Keywords: marsupial ; spermatozoa ; nucleus ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Spermatozoa of six species of Australian marsupials have been studied. The nucleus is highly unstable when compared with those of eutherian mammals. When thin films of spermatozoa in buffered saline are air-dried on glass slides, the nucleus disintegrates and flattens, leaving the acrosome, midpiece, and tail intact. This spreading of the nucleus can be inhibited by seminal plasma proteins and by bovine serum albumin, but is potentiated by detergents. The nucleus also decondenses spontaneously in the presence of high concentrations (〉0.25M) of calcium and magnesium salts, leaving the head membranes, acrosome, midpiece, and tail intact. This is inhibited by EDTA. In some species, certain areas of the nucleus appear more resistant t o Ca++/Mg++ treatment, and the initial stages of decondensation are uneven. Ultrastructurally the Ca++/Mg++ dispersed chromatin shows a moderately fine, branching, fibrillar structure, interspersed with dense granules. Treatment with disulphide bond cleaving agents together with detergents results in rapid and complete dispersal of the chromatin and acrosome, and slow digestion of midpiece and tail structures. Treatment with HCl, NaCl, KCl, EDTA, detergents, and sucrose has no effect on nuclear integrity, but treatment with NaOH (0.9-1.0M) results in complete digestion of the whole sperm. These findings are discussed in the light of evolutionary differences between marsupial and eutherian mammals in terms of sperm structure and composition.
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    Comparative ultrastructure of the yolk material in preimplantation stages of the hamster, mouse, and rat embryos (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 369-377 
    Details
    ISSN: 0148-7280
    Keywords: yolk ; preimplantation embryo ; ultrastructure ; hamster ; mouse ; rat ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Yolk material of preimplanation stages of embryos of the hamster, mouse, and rat were examined by a standardized electron microscopical procedure. The material was encountered as fibrils, scattered more or less densely in the cytoplasm. In the hamster, the material was present in large masses and the fibrils had a chain-like appearance when cut longitudinally. The ultrastructure of the fibrils was compatible with a helical pattern. The fibrils had a width of about 40 nm and the pitch (the axial distance of the repeating unit) was about 30 nm. In the mouse, the yolk material was dispersed in the cytoplasm forming small plaque-like groups. Also, in this species the fibrils were chain-like but smaller than in the hamster. The fibrils were often closely situated, resulting in images with varying crystalline appearances. In the rat, the yolk appeared as light areas occupying a substantial part of the cytoplasm. The fibrils in the yolk plaques were sparse and diffusely outlined. They were thinner than the fibrils of the mouse-yolk material, did not display any helical pattern at the resolution used, but showed a periodicity.
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    Announcement (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 405-406 
    Details
    ISSN: 0148-7280
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1120030411
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    Properties of the first and second factors released after hamster sperm make contact with the zona pellucida prior to fertilization in vitro (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 395-403 
    Details
    ISSN: 0148-7280
    Keywords: sperm-zona contact ; fertilization ; peptides ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: An investigation was made as to the nature of two of the factors, termed S1, released within the first 30 minutes after contact is made between capacitated hamster sperm and the zona pellucida in vitro. Previous studies showed that these S1 factors were detected two and 20 to 25 minutes after the gametes were combined and that, based on filtration studies, the former possessed a molecular weight of less than 5,000 daltons. The present results show that the quantity of the 20-25-minute S1 factor released into the supernatant increased linearly as a function of the sperm concentration. This factor passed unimpeded through a filter with a 5,000 molecular weight cutoff but only 42% of the activity traversed a filter with a cutoff of 2,000 daltons. The two-minute S1 factor, in the virtual total absence of cells, was stable for 10 to 15 minutes, but lost significant activity upon longer incubation. Under the same conditions, the 20-25-minute factor lost approximately 25% of its activity within 15 minutes, but remained stable at this level for at least 45 minutes of incubation. Both S1 factors were not affected by a mixture of glycosidases, but were inactivated by subtilisin, trypsin, and leucine aminopeptidase which was contaminated with endopeptidases. The activity of the two-minute S1 factor appeared more susceptible to the action of the proteases than that of the 20-25-minute S1 factor. In contrast to previous results obtained with the two-minute S1 factor, the release of the 20-25-minute S1 factor was not inhibited by the inclusion of soybean trypsin inhibitor a t concentrations which are known to inhibit penetration of the zona by the sperm. The results suggest that the two- and 20-25-minute S1 factors are peptides which are not identical.
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    A simplex optimized INDO calculation of 13C chemical shifts in hydrocarbons (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 36-45 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The variable-size simplex optimization method is used to reparametrize the I + A and β parameters of an INDO approximation to the perturbed Hartree-Fock calculation of 13C chemical shifts in hydrocarbons. The absolute shifts for 39 nuclei in a set of molecules containing up to four carbons are reproduced within a standard error of 9.9 ppm for an unconstrained optimization and to a standard error of 10.0 ppm for an optimization constrained to yield gross atomic charges in agreement with double-zeta ab initio calculations.
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    A pseudopotential SCF-MO study of Te42+ (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 64-68 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A recently developed ab initio pseudopotential molecular orbital approach was applied to the Te42+ ion, a system outside the practical reach of conventional all-electron treatments. Computations were carried out with a minimal STO-4G basis set. Results account reasonably well for the observed optical absorption spectrum and suggest the origin of a hitherto unassigned weak band. Ground-state properties, which included the structure, force field, and vibrational frequencies, were also investigated. Treated as a free, gas-phase ion, tetratellurium (II) yielded a bond length 0.05 Å shorter than the experimental value for the ion in a crystal lattice. Placement of static, point-charge counterions in the Te42+ coordination sphere increased the bond length to a value 0.005 Å longer than derived by experiment. Calculations on neutral, cyclic Te4 provided a theoretical single-bond reference length 0.09 Å longer than that obtained for the ion in a counterion environment. Comparisons between observed and calculated frequencies suggest an assignment of the vibrational spectrum different from the provisional assignment in the literature.
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    Molecular mechanics of organic halides. III. Fluorinated olefins (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 111-117 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A molecular mechanical force field for fluorinated ethylenes and propylenes is described. The field computes geometries, dipole moments, and energy differences between isomers and rotamers. Component analysis indicates that “classical” strains alone (skeletal, nonbonded, electrostatic) cannot account for energy relationships. The discussion is supplemented by a semiempirical quantum chemical comparison of cis- and trans-FCH=CHF and of gauche- and anti-FCH2CH2F.
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    The application of molecular mechanics to the structures of carbohydrates (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 99-109 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A study is reported of the accuracy with which the geometries of pyranose and methyl pyranoside molecules are predicted by molecular mechanics. Calculations of the conformational energies of the model compounds dihydroxymethane, methoxymethanol, and dimethoxymethane, made with the program MMI, produced results that compare well with previous ab initio molecular orbital calculations. This indicates that MMI gives a satisfactory account of the energetic and conformational aspects of the anomeric effect, a conclusion further supported by calculations on 2-methoxytetrahydropyran. The prediction of the observed preferred conformations of the primary alcohol group in aldohexopyranoses appears to be less satisfactory. MMI-CARB, a version of MMI with changes in some of the equilibrium C—O bond lengths of the program, has been used to calculate the geometries of 13 pyranose and methyl pyranoside molecules, the crystal structures of which have been studied by neutron diffraction. When the C—C—O—H torsion angles are constrained to approximately the values observed in the crystal structures, good agreement is obtained between the theoretical and experimental molecular geometries. The rms deviation for C—C and C—O bonds, excluding those significantly affected by thermal motion in the crystal structure determinations, is 0.005 Å. Corresponding figures for the valence angles that do not involve hydrogen atoms and for the ring torsion angles are 1.2° and 2.0°, respectively. The Cremer and Pople puckering parameters for the pyranose rings are reproduced within 0.026 Å in Q and 5.4° in θ.
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    Ab initio calculations of the rotational potential functions for propylamine and ethylmethylamine (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 281-284 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Calculations at the STO-3G and 4-31G levels have been carried out on propylamine and ethylmethylamine, using geometries determined by molecular mechanics by allowing complete molecular relaxation in all degrees of freedom except for torsion about the central bond, and at 30° increments for the latter. It was found that a butanelike potential exists in each case. From 0° (cis) to 360° in order, the 4-31G values for the energy extrema are 5.92, 0.12, 3.88, 0.00, 3.94, and 0.51 kcal/mole for propylamine (with the nitrogen lone pair gauche to carbon), and 7.06, 1.45, 3.44, 0.0, 2.87, and 1.44 kcal/mole for ethylmethylamine.
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    An ab initio study of the geometry and energy of six planar conformers of β-hydroxyacrolein (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 373-385 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Ab initio calculations with full geometry optimization have been carried out on the planar cCc, cTc, tTc, tCt, tTt, and cCt conformers of β-hydroxyacrolein using the 4-21G basis set, and on the cCc and cCt conformers using the 4-31G basis set. The hydrogen-bonded cCc conformer is the most stable and the cCt conformer the least stable, with the other conformers following the above sequence. β-Hydroxy substitution has scarcely any influence on the geometry of the trans-acrolein structure, whereas the geometry of the cis-acrolein structure shows significant changes which depend on whether the O—H group is cis or trans with respect to the CHO group about the C=C bond. The ΔET values for cis → trans isomerization about the C—C bond in cCt and cTc support the hypothesis that these changes in geometry are the result of a destabilizing interaction in cCt and a stabilizing interaction in cTc. The geometry of the hydrogen-bonded structure cCc sets it apart from all the other conformers: it has by far the longest C=C, the longest C=O, the longest O—H, the shortest C—C, and the shortest C—O. Its formation from cCt involves a lengthening of C=C, C=O, and O—H and a shortening of C—C and C—O, indicating a delocalization of charge within the ring. 4-21G calculations have also been made for a distorted cCt structure that has the same bond lengths and angles as the equilibrium cCc structure, and the distortion energy, cCt (equm. geom.) → cCt (distorted geom.), is found to be +13.1 kJ mole-1. Taking the energy of this distorted cCt structure as the baseline, the hydrogen-bonding energy in cCc is found to be  - 80.3 kJ mole-1.
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    Orbital topology. II. Orbital mapping of unsymmetrical molecules. A survey of the thermal isomerizations of dewar isomers of isoelectronically substituted benzenes, cyclopentadienes, and cyclopentadienyl ions (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 21-29 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Orbital mapping analysis, based on EHT and CNDO/2 semiempirical molecular orbitals, has been used to survey the thermal, disrotatory, ring-opening isomerizations of bicyclo[2.2.0]hexa-2,5-dienes (Dewar benzenes), bicyclo[2.1.0]pent-2-enes, and bicyclo[2.1.0]pent-2-en-5-yl ions to their planar isomers. Results indicate that isoelectronic substitution (CH replaced by C-, O+, N, NH+, etc.) in the molecular framework may favor allowed thermal reactions in some cases, in contrast to the disallowed reaction predicted for the parent hydrocarbons.
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    Metal-metal bond energies in Mo2, Mo2Cl84-, and Mo2(O2CH)4 (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 59-63 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Previous attempts to determine the strengths of multiple metal-metal bonds are reviewed. Estimates of 73 and 97 kcal/mole for the Mo—Mo bond energies in Mo2Cl84- and Mo2(O2CH)4, respectively, are obtained by combining the known experimental bond energy in Mo2 (96.5 ± 5 kcal/mole) with the results of SCF-Xα-SW calculations on Mo2, Mo2Cl84-, and Mo2(O2CH)4. Possible errors in the estimates are discussed. It is noted that the quadruple bonds in the complexes are predicted stronger per component than the sextuple bond in the diatomic.
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    On the gearing of methyl groups in hexamethylbenzene (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 76-80 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Empirical force field calculations were performed on hexamethylbenzene to elucidate the internal motions of the methyl groups. When the benzene ring is constrained to be planar (as in solid-phase studies), the methyl groups undergo a geared, disrotatory motion. When this constraint is relaxed, results are force field dependent. Calculated barriers are in good agreement with experimentally determined values.
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    Masthead (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
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    URL: http://dx.doi.org/10.1002/jcc.540010201
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    A theoretical approach to substituent effects.For previous articles in the series, see refs. 1 and 2. Interactions between directly bonded groups in the neutrals X—NH2, X—OH, and X—F and the anions X—NH- and X—O- (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 118-128 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Ab initio molecular orbital calculations have been carried out for the neutrals X—NH2, X—OH, and X—F and the anions X—NH- and X—O- with substituents X = Li, BeH, BH2, CH3, NH2, OH, and F. All structures have been fully optimized with the 4-31G basis set which is found to perform considerably better than the minimal STO-3G basis in predicting the lengths of strongly polar bonds. A quantitative analysis of interactions between the directly bonded groups, utilizing energy changes in hydrogenation reactions, is presented and rationalized with the aid of perturbation molecular orbital theory. Favorable interactions occur when electron-donor groups bond to electron-acceptor groups. This applies to both σ and π interactions, the relative importance of which depends on the particular substituents.
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    The structure of carbon trioxide (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 199-203 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Open (1) and cyclic (2) singlet forms of CO3 were investigated by means of ab initio calculations. At the highest level of theory employed, MP2/6-31G* (which includes the effects of electron correlation), 2 was indicated to be much more stable than 1 and thermodynamically stable toward dissociation into CO2 and O(3P). The open form 1 has a long O—O bond and can be regarded as a weak dative complex between CO2 and a singlet oxygen atom.
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    Genetic influences on mouse sperm capacitation in vivo and in vitro (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 343-349 
    Details
    ISSN: 0148-7280
    Keywords: Sperm ; capacitation ; mouse strain differences ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Intial in vivo studies were performed to observe the proportion of eggs fertillized at specific intervals after natural mating and ovulation in our research mouse colony. Proestrous females of the C57BL/10Wt, SJL/Wt inbred strains and the F1 hybrid cross (B10 × SJL or reciprocals) were paired in the after-noon with males of their respective strain and examined for vaginal plugs at the midpoint of the dark period (2400 hours). Oviducts were periodically collected from mated females, and ovulation was first observed at 4, 5.2, and 3 hours after 2400 hours in the B10, SJL, and F1 hyrid, respectively. The clutch of eggs from each ovulating female, was placed in culture, and cleavage oviduct lavage verifying female mating was placed in culture, and cleavage was used as the criterion for fertilizaition. Fifty percent of the eggs were fertilized 2.2, 5.0, and 2.5 hours after ovulation in B10, SJL, and F1 hybrid females, respectively. Because twice the legth of time was required to fertilize a similar proportion of eggs from the SJL strain as the F1 hybrid, these two strains were used for determining their rate of fertilization under more fully controlled conditions in vitro. Forty-nine percent of F1 hybrid eggs were fertilized after 4 hours incubation with SJL epididymal sperm, whereas 53% fo SJL and 56% of F1 hybrid eggs were fertilized after only 2 hours incubation with F1 hybrid epididymal sperm. Thus, using sperm from these two mouse strains, the amount of time required to fertilize approximately 50% of the eggs within a clutch both in vivo and vitro was very similar. These observations demonstrte teh validity of using this in vitro system for fertilization studies and confirm that the temporal events in sperm capacitation and egg penetration are dependent on the genotype of the sperm. Similarities in fertilization rates at specific times after ovulation or insemination in vitro imply that the initiationof sperm capacitation in vivo occurs near the time of ovulation and several hours after mating. We tentatively suggest that follicular fluid may be required for completion of mouse sperm capacitaiton in vivo.
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    Aging of mouse eggs in vivo and in vitro (1980)
    New York, NY : Wiley-Blackwell
    Gamete Research 3 (1980), S. 379-393 
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    ISSN: 0148-7280
    Keywords: aging ; ova ; acid phosphatase ; superovulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Morphological and cytochemical (acid phosphatase) changes associated with mouse ova and cumulus cells aged within the oviducts (in vivo) or in culture (in vitro; 1-24 hours postovulation) have been investigated. Structural alterations of cumulus cells were apparent immediately after ovulation and included nuclear pycnosis and cytoplasmic vacuolization. Nevertheless, approximately 30% of the cumulus masses examined contained cells that plated out when cultured and remained viable for up t o three days in vitro. From 12 t o 24 hours postovulation almost all cumulus cells of specimens aged in vivo showed signs of degeneration. Disruption of the meiotic spindle and an increase in acid phosphatase positive organelles were characteristic of in vivo and in vitro aging ova. The percentage of fragmented eggs obtained from super-ovulated (5 IU PMS followed by 5 IU HCG) mice approximately one and 24 hours postovulation was not significantly different. Eggs obtained from superovulated animals and aged in vitro for 24 hours yielded significantly more fragmented ova. Fragmented eggs were not obtained from cycling females on the morning of estrus. When such eggs were cultured in vitro for 24 hours the percent fragmentation was significantly lower than that for aged eggs obtained from super-ovulated mice. These results indicate that 1) similar morphological alterations occur among cumulus cells and eggs aged either in vitro or in vivo, 2) ova from superovulated mice do not constitute a homogeneous population and 3) the method of superovulation employed in this study induces the ovulation of a relatively large group of eggs that are susceptible to fragmentation when cultured in vitro.
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    Isomeric structures of protonated ozone: A theoretical study (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 94-98 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Ab initio molecular orbital calculations have been used to determine the structure of protonated ozone. Four stable minima were found on the O3H+ singlet potential energy surface. Three forms correspond to ozone protonated at the central oxygen (C2v) or at the terminal oxygen (two Cs isomers, E and Z). The fourth isomer (Cs) is a derivative of trioxirane. The most stable structure is the planar E form I. The proton affinity of ozone (to give I) is given as 123.6 kcal/mole (MP2/6-31G*//4-31G). The energy difference between I and protonated trioxirane VI is greater than that between ozone and trioxirane.
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    The C4H4CO potential surface. Reactions involving bicyclo[2.1.0]pentenone (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 129-133 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: MNDO and MINDO/3 calculations were used to study the photochemical formation, thermal rearrangements, and dissociation of bicyclo[2.1.0]pentenone. The “forbidden” thermal conversion to cyclopentadienone requires little activation, which accounts for the low kinetic stability of bicyclo[2.1.0]pentenone. The theoretical results seem to be compatible with the available experimental evidence for the tri-tert-butyl-substituted systems and suggest an explanation for observed differences in reactivity.
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    The structure and energies of some unsaturated four-membered ring carbocycles (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 30-35 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A number of cyclobutane derivatives containing one or more double bonds in endo- or exocyclic positions have been studied by the molecular mechanics method within the context of the MM2 force field. Generally speaking, the structures and energies of these compounds are well calculated in cases in which they are known experimentally and are predicted in others. Examples are shown of the use of the moments of inertia of molecules, which are known from microwave studies, in conjunction with molecular mechanics calculations to yield better structures than could be obtained by either method alone. Compounds examined include cyclobutene, methylenecyclobutane, Dewar benzene, and related compounds.
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    Conformational analysis of proteins: Algorithms and data structures for array processing (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 46-58 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Current efforts to determine the nature of the interactions that influence protein folding involve, among other things, minimization of an appropriate empirical conformational energy function (ECEPP, Emprical Conformational Energy Program for Peptides) to obtain the native structure. Because of the prohibitive cost of such a massive computational project, either on a conventional large-scale machine at a self-supporting installation or on a dedicated minicomputer, an alternative computer hardware system has been developed to aid in the conformational analysis of proteins. It consists of a Floating Point Systems AP-120B array processor and a Prime 350 minicomputer host. A version of ECEPP has been adapted to run on the AP-120B. The data structures and algorithms chosen for this version reflect the highly unusual parallel architecture of this machine. Benchmark comparisons with BPTI (Bovine Pancreatic Trypsin Inhibitor), a protein of 58 residues and a known structure, have been carried out on this system as well as on an IBM 370/168. They show a significant advantage in speed for the AP-120B/Prime 350 system as well as a substantially lower cost. An energy minimization of BPTI with 154 variable dihedral angles is reported, an effort heretofore prohibited by the computer costs involved.
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    Integrated spatial electron populations in molecules: Application to simple molecules (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 81-87 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The electron projection function P(x, z) = ∫ ρ(x, y, z) dy is used to evaluate charge transfer and covalency in two series of molecules, LiX and CH3X (X = Li, BeH, BH2, CH3, NH2, OH, and F), with wavefunctions derived from STO-3G, 4-31G, and, in some cases, 6-31* ab initio calculations. The precision of the method and comparison with Mulliken populations analysis are described. Particular attention is given to CH3Li which by our criteria is wholly ionic.
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    Atomic Xα calculations based on EHFS(α) = Eexp (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 88-93 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The total energies and one-electron energies for first- and second-row atoms were calculated by using the Hartree-Fock and the Hartree-Fock-Slater Hamiltonian with Xα orbitals, ui(αexp); α was parametrized from EHFS(αexp) = Eexp. The EHF(αexp) total energies are always higher than the Hartree-Fock energies for the atoms. The relation of the calculated ionization potential to the experimental ionization potential depends on the α used to define ui(α), αexp, or αHF.
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    On the relative importance of core and valence shell representations in the calculation of conformational energies using small Gaussian basis sets (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 134-140 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Several “core-deficient” small Gaussian basis sets were constructed and analyzed in terms of the balance requirements of functions that contribute predominantly to the core. Variations in the conformational energy barriers and geometrical parameters for ammonia and ethane, calculated with these basis sets, were analyzed with a gradient technique. A scheme for the reduction of the size of molecular basis sets is proposed.
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    Conformational energy surfaces of triplet-state isomeric methyloxiranes (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 141-148 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A conformational study was carried out on the three ring-opened structures of triplet methyloxirane with a minimal Gaussian basis set, within the unrestricted Hartree-Fock framework. For the two structures energy surfaces E(θ1, θ2) were generated, where θ1 measures the methyl rotation and θ2 is associated with the torsion about the other C—C bond. For the third structure an energy hypersurface E(θ1, θ2, θ3) was generated, where energy was a function of methyl rotation θ1 and two nonequivalent C—O rotations θ2 and θ3. Analysis of the surfaces revealed the locations and relative energies of the critical points (minima, saddle points, and maxima). The overall stereochemical finding was that these ring-opened triplet C3H6O species possessed rather flexible structures.
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    Applications of molecular mechanics calculations in carbohydrate chemistry. I. Conformational and constitutional equilibria of tetraoxabicyclo[4.4.0]- and -[5.3.0] decanes, bicyclic diacetals of alditols (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 192-198 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The energies of various conformations have been calculated by molecular mechanics for cis and trans isomers of 2,4,7,9-tetraoxabicyclo[4.4.0] decane and 3,5,8,10-tetraoxabicyclo[5.3.0]decane and their methyl derivatives. These molecules are models for reaction products from formaldehyde and the tetrols, pentitols, and hexitols. The conformational equilibria were analyzed for the cis-bicyclo [4.4.0] and cis-bicyclo[5.3.0] systems and compared with available experimental data. The thermodynamic stability of bicyclo[4.4.0] products was found to be higher than that of bicyclo[5.3.0] derivatives in the gas phase in every case studied. Discrepancies with experimental data that exist in a few cases can be ascribed to solvent effects.
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    A theoretical comparison of cationic and anionic homoaromaticity: Reinforcement of cationic homoaromaticity by σ-nonclassical effects (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 189-191 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A MINDO/3 study of homoaromaticity in the 3-cyclobutenyl cation and the Mobius 3-cyclobutenyl anion has been used to evaluate cationic and anionic homoaromaticity quantitatively. π Homodelocalization energies of the two are found equal in isostructural planar comparisons. In planar optimized structures, the homodelocalization energy of the cation is slightly (about 4 kcal) greater than that of the anion, a consequence of the greater 1,3 distance in the latter. Full optimization produces a highly puckered and further stabilized cation, but engenders no change in the Mobius anion. The total stabilization of the cation relative to the anion is 13 kcal, in accord with the generalization that cationic homoaromaticity is more potent than the anionic variety. The fully optimized cation is revealed to actually have a much smaller π homodelocalization energy than the optimized anion, in contrast to the order of overall stabilities. σ-Nonclassical effects, which are stabilizing in the cation but destabilizing in the Mobius anion, provide the rationale for the above.
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    Masthead (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980) 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540010301
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    A systematic preparation of new contracted Gaussian-type orbital sets. III. Second-row atoms from Li through ne (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 205-228 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Four minimal Gaussian basis sets are generated for the second-row atoms Li through Ne. The first one, MINI-1, consists of a 3-term contraction of primitive Gaussian-type orbitals for 1s, 2s, and 2p atomic orbitals. The convenient shorthand notation would be (3,3) for Li—Be and (3,3/3) for B—Ne. The second one, MINI-2, can be represented by (3,3/4) for B—Ne. In the same way, MINI-3 is described as (4,3) for Li—Be, and MINI-3 and MINI-4 are represented by (4,3/3) and (4,3/4) for B—Ne, respectively. Although the four basis sets are the minimal type, they give the valence shell orbital energies which are close to those of DZ. These four and other sets derived from them are tested for the hetero- and homodiatomic molecules and some organic molecules. They are found to give the orbital energies that agree well with those given by extended calculations. Atomization energies and other spectroscopic constants are also calculated and compared with those of extended calculations. The results clearly indicate that the present basis sets can be used very effectively in the molecular calculations.
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    An analysis of the molecular packing of maleic hydrazide (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 261-265 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A molecular packing analysis of the hydrogen-bonded layer structure of maleic hydrazide shows that even in such a structure, the van der Waals energy is the dominant component of the lattice energy. The hydrogen-bond energy of the observed structure is greater than that for alternative structures based on a different mode of hydrogen bonding, and this makes the observed more stable.
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    Ab initio calculations of the rotational potential functions for propanol and ethyl methyl ether (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 285-287 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Calculations at the STO-3G and 4-31G levels have been carried out on propanol and ethyl methyl ether, with geometries obtained from molecular mechanics calcualations. Full relaxation was allowed in all degrees of freedom except for the torsion about the central bond, which was varied at 30° increments. A butane-type potential was found, the maximum and minimum values of energy are from 0° to 180° 5.55, 0.00, 4.02, and 0.00 kcal/mole for propanol, and 8.35, 2.74, 3.31, and 0.00 kcal/mole for ethyl methyl ether (4-31G).
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    The electrostatic potential of yeast tRNAPhe. II. The potentials of the phosphate groups in their various conformational states (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 301-306 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The range of conformational states of the phosphate groups observed in the published crystal structure of tRNAPhe is used as the basis for theoretical studies on the effect of conformation on the electrostatic potentials of these moieties. Deductions concerning the influence of these effects on the potential of a complete tRNAPhe macromolecule are presented.
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    A comparative study of the structure and bonding of HOO, HOS, HSO, and HSS radicals by CNDO/2 and INDO methods (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 334-340 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Equilibrium geometries, force constants, barriers to linearity, charge distributions, dipole moments, and electron spin density of HOO, HOS, HSO, and HSS radicals are calculated by CNDO/2 and INDO methods using respectively the original and some recently introduced scheme of parametrization. Three sets of calculations, namely, CNDO/2(sp), CNDO/2(spd), and INDO, are performed, and the results are compared with the ab initio and experimental values, wherever available. A good agreement is obtained for geometry in the case of CNDO/2 (sp) and INDO calculations. The performance of CNDO/2 (spd) calculations in this regard is quite unreliable. The stretching force constants are considerably overestimated by all the methods, while the bending force constants are in reasonable agreement with the ab initio values. With respect to dipole moments, the CNDO/2 values are in better agreement with the ab initio results than the INDO values. In all the cases, the dipole moment vector directions are in complete disagreement with the ab initio predictions.
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    A theoretical study of paths for decomposition and rearrangement of dihydroxycarbene (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 158-166 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The transition states for fragmentation of dihydroxycarbene [C(OH)2] to H2 and CO2 and for the rearrangement of this carbene to formic acid were located by ab initio calculations. The relative energies of the transition states were determined at several levels of theory and the basis set dependence of the energies is discussed. At the best level of theory; using a basis set of double-zeta quality augmented by polarization functions and with the inclusion of extensive CI, we found that the transition state for fragmentation was considerably higher in energy than that for rearrangement. This finding is at variance with the predictions of the Woodward--Hoffmann rules because fragmentation represents an “allowed” reaction, whereas rearrangement is “forbidden.” In conformity with the Woodward-Hoffman rules, the transition state for rearrangement was found to be close in energy to H· + ·CO2H. The even higher energy of the transition state for concerted fragmentation to H2 and CO2 is attributed to the need for the latter fragment to remain substantially bent in order to permit H2 formation while maintaining a modicum of OH bonding. Difficulties in locating the transition state for concerted fragmentation are discussed and a new method for finding transition states is proposed.
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    The barrier to internal rotation in Ge2H6 (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 185-188 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: High-quality SCF-MO calculations yield a barrier to internal rotation of 1.70 kJ mole-1 for Ge2H6. A new contraction scheme is reported for Dunning's larger Ge basis set. Geometry optimization, although carried out, is unimportant in this particular calculation. Wavefunctions and properties are reported for GeH4 and the staggered and eclipsed conformers of Ge2H6. The magnitude of the calculated barrier is more physically reasonable than those deduced from experimental data. Comparisons are made across the two series X2H6 and CH3XH3.
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    Masthead (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980) 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
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    URL: http://dx.doi.org/10.1002/jcc.540010101
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    An ab initio study of the geometry, harmonic and anharmonic force fields, and fundamental vibrational frequencies of cis- and trans- thiolformic acid (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 167-177 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The geometry, harmonic and anharmonic force fields, and fundamental vibrational frequencies of cis- and trans-thiolformic acid are studied ab initio in the 4-31G basis set. An extensive comparison is made between changes in diagonal and off-diagonal quadratic and cubic force constants and diagonal stretching quartic constants in going from the chain to the ring structure in thiolformic acid and formic acid. The changes in the force constants are indicative of a much weaker interaction in the trans conformer between S—H and O=C, compared with O-H and O=C, in keeping with the weaker hydrogenbonding property of the S—H group in general.
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    A note on density matrix extrapolation and multiple solutions of the unrestricted Hartree-Fock equations (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 178-180 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Unrestricted Hartree-Fock (UHF) SCF-MO calculations on the doublet reaction surface for the addition of methylidyne (CH) to ethylene (C2H4) using the standard extrapolation techniques of the GAUSSIAN 70 program show erratic behavior. On the other hand, the potential energy surface calculated without extrapolation of the density matrix and by using the final density matrix of a neighboring point as the initial guess for the density matrix for the new point gave a smooth potential curve without any kinks or erratic pattern. Therefore, the density extrapolation technique should be used with particular caution in UHF calculations.
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    The computational application of the Cahn-Ingold-Prelog rules 1 and 2 (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 229-232 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Cahn-Ingold-Prelog (C—I—P) rules 1 and 2 (material differences) have been expressed in the formal logic of a high-level computer language (FORTRAN IV) on a laboratory minicomputer (PDP 11/40) by the program CHIRAL. An oversight in the C—I—P formalism in the treatment of rings was treated on an ad hoc basis; the problem has been expressed simply in terms of elementary graph theory in a way consistent with and similar to chemical notation. An example of the operation of CHIRAL is provided and the internal procedures discussed.
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    Graphite: A molecular mechanics treatment (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 257-260 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Graphite is the limiting case of an infinite aromatic hydrocarbon, and as such is an important benchmark in force-field calculations. Using experimentally determined physical properties for graphite, a force-field parameter set was developed for molecular mechanics calculations with unsaturated hydrocarbons and is described and discussed.
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    A theoretical approach to substituent effects.For previous articles in this series, see ref. 1. Structural consequences of electrostatic and orbital interactions in model mono- and disubstituted methanes (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 295-300 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Ab initio molecular orbital theory is used to examine the effect of substituents on bond lengths in mono- and disubstituted methanes. The relative importance of electrostatic and orbital interaction terms are assessed. The results suggest that for substituents (X) which show powerful σ effects and weak π interactions (e.g., F), the changes in bond length are due primarily to the electrostatic component except in some disubstituted methanes in which case the change in the hyperconjugative ability of the C - X bond is also important. On the other hand, substituents X which show weak σ effects but powerful π interactions (e.g., NH2) affect bond lengths primarily through hyperconjugative interaction of a filled or vacant π-type orbital on X with the adjacent bonds.
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    Prediction of the crystal structure of a cyclic tetrapeptide (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 368-372 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Prediction of the known crystal structure of cyclic-L-Ser(O-t-Bu)-β-Ala-Gly-L-β-Asp(OMe) has been attempted by establishing the low-energy conformations of the isolated molecule by conformational analysis, and then regarding each of these as a rigid molecule, by establishing the favorable crystal packing arrangements by molecular packing analysis. The theoretical model closest to the observed structure was one of the lowest-energy solutions and was recognized as essentially correct by reference to the x-ray data. The limitations of the model follow from the fact that the side chain conformations are somewhat affected by packing interactions.
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    Random walks and their diagnostic value for characterization of atomic environmentDedicated to Professor A. T. Balaban for his pioneering work in reviving interest in chemical graph theory. (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 386-399 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A characterization of atomic environments based on counting random walks in a molecular skeleton is outlined. To each atom in a molecule a sequence of integers w1, w2, w3,…, wn is assigned, where wi represents the number of self-returning walks of length k, the length being defined by the number of bonds traversed. Properties of the derived atom codes are discussed. The codes display an impressive diversity and are superior to atomic codes based on enumeration of self-avoiding walks (or paths) in discriminating atomic environments. In certain cases the codes of individual atoms are not unique and the same codes appear in different molecules or even within the same molecule. The occurrence of the nonunique codes can be related to special structural situations, associated with the occurrence of isospectral graphs. These isospectral graphs which have atoms with identical codes can generate additional isospectral structures by attaching any arbitrary group to such points. If nonequivalent atoms of a single molecule have identical random walk codes, substitution at the singular points alternatively will produce isospectral graphs. Examples of such situations are given.
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    Localized molecular orbitals and chemical binding in five-membered heterocycles. II (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 358-367 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The localized molecular orbitals (LMOs) of thiophene, furan, and pyrrole are derived from ab initio 4-31G wavefunctions using Boys' criteria for localization. From the transferability point of view, these LMOs are classified as (i) completely different and nontransferable LMOs (these are the lone-pair orbitals on O and N on one hand and those on S on the other hand), (ii) chemically similar lone pairs and inner shells on O and N (of furan and pyrrole, respectively), and (iii) chemically equivalent C—C, C=C, and C—H LMOs in the three heterocycles. The sp3 hybridization of the L core of sulfur, its appreciable polarization, and considerable involvement in bonding in the C—S bond region have been discussed. The present investigation indicates the limitation of the application of semiempirical MO methods to molecules that contain second-row atoms due to both the appreciable core - valence and π-σ interactions involving such atoms. Qualitative investigation of aromaticity and reactivity of the studied heterocycles agrees satisfactorily with experimental observations and shows that conclusions drawn based solely on static factor considerations (charge distribution in the noninteracting molecules) might very well be misleading and such factors determine the ease rather than the final orientation of the substituent.
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    Quantum chemical investigations of charge transfer interactions in relation to the electronic theory of cancer. IV. The interaction of formamide and the enol tautomers of several glyoxals (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 400-406 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The results of ab initio “supermolecule” calculations of the charge transfer between formamide and the enol forms of methylglyoxal, ethylglyoxal, dimethylglyoxal, and propenylglyoxal are compared for several different conformations of the constituent molecules. The enols were found to be poorer electron acceptors than their respective keto isomers.
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    Properties of strong hydrogen-bonded systems. II. Ab initioSCF-MO study of the hydrogen bond between nitric acid and ammonia (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 417-419 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The hydrogen-bonded complex between nitric acid and ammonia molecules has been studied by the ab initio molecular orbital method using the 4-31G basis set. The calculated interaction energy for the complex (ΔE = -91.4 kJ mole-1) indicates that one is dealing with the strongest “nonionic” H-bonded complex considered hitherto by theoretical methods. Other properties of the hydrogen-bonded complex such as geometrical parameters, dipole moment, amount of charge transfer, and stretching force constants of the O—H and (OH)… N bonds are calculated and discussed.
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    Orbital topology. I. A basic topological model for chemical systems, an orbital mapping technique, and analyses of model, thermal electrocyclic reactionsThis article is based in part on D. R. Kelsey's Ph.D. Thesis, California Institute of Technology, Pasadena, California, October 31, 1972; a brief discussion of these concepts and results has been presented at the American Chemical Society's 172nd National Meeting, San Francisco, September 2, 1976, abstract ORGN 199. (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 3-20 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A topological model which provides a unifying framework for chemical reactions and molecular structure is proposed. Such basic concepts as overlap, orthogonality, reaction continuity, reaction reversibility, and orbital correspondence are incorporated into the model in a logical fashion. A chemical reaction pathway is regarded as a function that transforms a reactant topological space into its equivalent product space. The unique character usually ascribed to reactants, products, and their wavefunctions is superfluous. The model also allows considerable approximation of the wavefunctions and the reaction pathway without affecting the overall result. A simple orbital mapping technique consistent with the model which traces the transformation of orbitals using intermolecular overlaps of the orbitals is also proposed. The suitability of a given pathway (“allowed” or “forbidden”) can be deduced explicitly without invoking symmetry (or other) rules and without resorting to detailed calculation of reaction energy surfaces. The validity of the mapping procedure has been confirmed by several thermal electrocyclic reactions: the ring-opening isomerizations of substituted cyclopropyl cations, cyclopropyl anion, cyclopropanone, cyclobutene, benzocyclobutene, Dewar benzenes, and 1,3-cyclohexadiene. Orbital mapping with EHT and CNDO/2 MOs correctly predicts the reaction stereochemistry (conrotatory or disrotatory) in every case.
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    A systematic CI procedure with modified virtual orbitals (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 69-75 
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    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The use of modified virtual orbitals is studied in a systematic conventional CI procedure which offers considerable potential in regard to convergence and extension to larger systems. The method is applied to the HCN molecule by using 37 basis functions, and analysis of energy expectation values, together with the one-electron density, yields some insight into the physical content of CI wavefunctions.
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    Graph theoretical characterization and computer generation of certain carcinogenic benzenoid hydrocarbons and identification of bay regions (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 149-157 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An algorithm is developed for generating and characterizing carcinogenic catacondensed benzenoid hydrocarbons. The bay regions in these structures are identified by a technique that we developed at Johns Hopkins. Using the three-digit code proposed by Balaban, and the concept of ring adjacency matrix expounded here, we generate catacondensed benzenoid hydrocarbons in the computer and identify the number of potentially carcinogenic bay regions in each of them. The results of computer generation agree with the combinatorial enumeration of Harary and Read. All structures containing up to five rings and some with six rings and the number of bay regions in these are presented. Computer results for the structures and bay regions of all seven-, eight-, and nine-membered unbranched catacondensed benzenoid hydrocarbons and the number of bays are available from the authors.
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    The torsional potential function for n-butane (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 181-184 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The energies of four different conformations for n-butane were calculated by the ab initio method using an STO-3G basis set. Fully relaxed molecular geometries obtained from molecular mechanics (MM2) were used. The two energy minima [anti (C2h), gauche (C2)] and the two maxima (C2, C2v) had the following relative energies: 0.0, 0.88, 3.56, 5.99 kcal/mole. These are approximate Hartree-Fock numbers. It is estimated that inclusion of electron correlation in the calculation would lower the last number to about 5.1 kcal/mole while leaving the first three values essentially unchanged.
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    Evaluation of MINDO/3 calculated structures. II. Branching errors in alkanes and cycloalkanesFor Part I see ref. 1. (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 233-239 
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    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: MINDO/3 calculations have been carried out for a series of branched chain alkanes in order to assess effects of branching on calculated geometries and heats of formation (ΔHf). With vicinal branching, MINDO/3 calculates the central C—C bond to be too long. Bond angles are also found to be distorted. Errors in calculated heats of formation are large when geminal branching is present and significant with vicinal branching. Branching error corrections for ΔHf have been derived and applied to a separate series of branched acyclic and cyclic compounds. For the test sample, application of the branching error corrections gave calculated structures of acyclic branched hydrocarbons with heats of formation having an average absolute error of 1.3 kcal/mole rather than 17.3 kcal/mole before correction. Cyclic branched hydrocarbons are shown to be less well corrected. Calculations of heats of reaction have also been carried out for some isomerization and cyclization reactions using the MINDO/3 and MNDO methods. It is clear from the comparisons that MNDO calculations give less severe errors for highly branched compounds but the errors are still substantial. For prediction of heats of reaction, the error-corrected calculations are shown to be superior to the “raw” calculations obtained by MINDO/3 or MNDO.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540010304
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    Quantum chemical investigations of charge transfer interactions in relation to the electronic theory of cancer. II (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 275-280 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The results of ab initio “supermolecule” calculations of the charge transfer between formamide and methylglyoxal, ethylglyoxal, and dimethylglyoxal are compared for several different relative conformations of the constituent molecules. The charge transfer properties of ethylglyoxal were found to be quite different to those of the other two glyoxals.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540010309
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  • 88
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    Electronic Resource
    Masthead (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980) 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540010401
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  • 89
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    Electronic structure of benzaldehyde: A comparative study of the lowest excited singlet π* ← π and π* ← n states (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 288-294 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: VE-PPP, CNDO/2, and CNDO/s-CI methods have been used to investigate the electronic spectrum and structure of benzaldehyde. Electronic charge distributions and bond orders in the ground and lowest excited singlet π* ← π and π* ← n states of the molecule have been studied. The molecule has been shown to be nonplanar in the lowest π* ← n excited singlet state, in agreement with the conclusions drawn from the study of vibrational spectra. Dipole moments in both excited states have been shown to be larger than the ground-state value. Thus, the ambiguity in the experimental result for the π* ← π n excited singlet state dipole moment has been resolved. It has been shown that the n orbital is mainly localized on the CHO group. Furthermore, charge distributions, dipole moments, and molecular geometries are shown to be very different in the excited singlet π* ← π and π* ← n states.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540010312
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  • 90
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    Small elemental clusters. I. The structures of Be2, Be3, Be4, and Be5 (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 307-322 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The geometries and energies of beryllium clusters up to Be5 are examined using ab initio molecular orbital theory. Allowances are made for electron correlation with Møller - Plesset perturbation theory to fourth order. Correlation is found to have a dramatic effect on the relative energies of the several structures examined for Be4 and Be5. Furthermore, the effect of d-type basis functions on the correlation energy results in an increased binding energy for the clusters. Be2 is only weakly bound. For Be3, the best estimate of the binding energy is 6 kcal/mole for the singlet equilateral triangle. Be4 is tetrahedral in its ground state and the estimated binding is 56 kcal/mole. The best structure for Be5 is a singlet trigonal bipyramid, and the binding energy is 88 kcal/mole at the highest level of theory used.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540010402
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  • 91
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    Spectroscopic CNDO/CI study of some cyclic polyenes (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 341-347 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: CNDO/S calculations are carried out on 1,3,5-cycloheptatriene (I), 1,3,5,7-cyclooctatetraene (II), all-cis-1,3,5,7-cyclononatetraene (III), and all-cis-1,4,7-cyclononatriene (IV), for which π-σ separability is a questionable matter. When disparate choices are available for the geometries, preferences are based on the agreement between calculated and experimental spectra. The microwave structure for I and an unsymmetrical conformation for III are suggested. In the electronic spectra, conjugative contributions are assigned to the lowest-energy weak band, while an ethylenic nature is to be attributed to the intense band in the range of 6 eV. The possibility of through-space π interactions is examined qualitatively. An appreciable degree of such interaction is shown by IV.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540010405
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  • 92
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    INDO-Type calculations on the ground state and various ionic states of transition metal tricarbonylsPart 10 in the series “Electronic Structure of Organometallic Compounds.” For Part 9, see ref. 1. (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 407-416 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: By means of the ΔSCF and transition operator (TO) methods based on a recently developed INDO extension to the first transition metal series, the first ionization potentials of benzene - chromium tricarbonyl (I), cyclopentadienyl manganese tricarbonyl (II), the iron - tricarbonyl complexes with trimethylenemethane (III), and cyclobutadiene (IV) have been calculated and compared with experimental data. It is shown that the electronic structure of I to IV can be rationalized by Hoffmann's fragment approach in both the ground state and the cationic hole states. Within the series I - IV there are remarkable energy differences in the ground state for MOs derived from the 1a1 and 1e orbitals of the M(CO)3 fragment. The observation that only one band is associated with the ionization events from MOs predominantly localized at the metal site is traced back to large relaxation effects. In the cationic hole states the split of the M(CO)3 fragment orbitals 1a1 and 1e is minute in all four compounds.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/jcc.540010412
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  • 93
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    The electronic structure and optical activity of conjugated dienes: 1,3-Butadiene and α- and β-phellandrene (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 240-256 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The optical activity of conjugated dienes is investigated by means of ab initio SCF-CI calculations. The computed electronic spectrum of trans-1,3-butadiene is shown to be in good agreement with the results of more rigorous calculations of the valence transitions and in satisfactory agreement with experiment. The optical rotatory strengths of the lower electronic transitions of twisted 1,3-butadiene as a function of dihedral angle are presented and simulated CD spectra are produced. The N → V1 (π2 → π3*) transition is predicted to have a positive rotational strength for all dihedral angles that correspond to a right-handed twist of the chromophore, in accord with the empirically deduced “diene rule” although for a twist angle of 60°, the rotatory strength is calculated to be almost zero. The role of the orientation of allylic bonds is investigated in the model system 1-butene in which the rotational strength of the π → π* transition as a function of rotation about the 2,3 bond is determined. The effect of allylic bond disposition in dienes on the optical activity of the long-wavelength π2 → π3* transition is simulated by use of the exciton coupling model of Harada and Nakanishi in which two 1-butene molecules with suitable geometries are coupled via interactions of the electric dipole transition moments of their π → π* transitions. The model systems 1,3-butadiene and 1-butene are used to rationalize the apparently anomalous optical activity of (-)-α-phellandrene and (-)-β-phellandrene, both of which should have a diene chromophore with a right-handed twist in their most stable conformers and so should be dextrorotatory. The experimental CD spectrum of α-phellandrene is determined at several temperatures down to -180°C. The observed variation of the apparent rotational strength of the N → V1 transition is in good agreement with that predicted by use of the exciton coupling model.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540010305
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  • 94
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    A method for constrained energy minimization of macromolecules (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 266-274 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Two algorithms for the local energy minimization of the structure of macromolecules in the presence of constraints are proposed. They are a combination of the method of steepest descents and the method of conjugate gradients with the procedure SHAKE, by which distance constraints can be satisfied. The two algorithms are tested by applying them to a small protein, the bovine pancreatic trypsin inhibitor (BPTI), and compared with the penalty function method for conserving constraints. The efficiency of the proposed methods depends on the level of interdependence of the constraints. For bond-length constraints, the use of SHAKE is superior to the penalty function method. However, when bond-angle constraints are included, SHAKE is more efficient only if the curvature of the penalty function is considerably greater than that of the potential function being minimized. The results indicate that with bond-length constraints the minimization behavior is similar to that without constraints. However, the simultaneous application of bond-length and bond-angle constraints appears to confine the molecule to a very limited part of configuration space, very different from the part covered by an unconstrained minimization. This conclusion calls into question energy minimizations of protein systems in which only the dihedral angles are allowed to vary.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540010308
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  • 95
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    Systematic synthesis design. 8. Generation of reaction sequencesFor previous articles in this series, see ref. 1. (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 323-333 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The numerical description of functionality allows a rigorous generation of all reactions from one structure (or partial structure) to another. The minimum number of steps required can be calculated and this “reaction distance” used to guide computer generation of sequences to converge on the target structure. A computer algorithm is described for efficient generation of all shortest synthetic routes between two given molecules as starting material and product. The program is seen as a prototype of a complete synthesis design program.
    Additional Material: 7 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540010403
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  • 96
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    Molecular charge distribution and chemical binding in five-membered heterocycles. I (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 348-357 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Electron density maps for the heterocycles thiophene, furan, and pyrrole are determined from ab initio 4-31G wavefunctions. The charge distributions in these molecules are analyzed in terms of the total molecular density and difference density maps and their profiles. The atomiclike core, especially the L core of sulfur, is found to play an important role, via its polarization and interaction, in determining the extent and direction of valence density transfer from the carbon to the heteroatom. The changes in the charge distributions that occur in the immediate vicinity of the heteroatoms and the relation of density quantities to binding and antibinding characteristics are discussed. The quantum topological features of the molecular charge distributions of the three heterocycles are analyzed and discussed and the different bonding situations, e.g., ring strain, ionic and covalent binding, etc., are compared in a model-independent way.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540010406
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  • 97
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    Benzophenon-dilithium als Komplex mit Tetrahydrofuran und Tetramethylethylendiamin (1980)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 92 (1980), S. 844-845 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19800921017
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  • 98
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    Electronic Resource
    Thermische Cycloadditionen von Acetylendicarbonsäure-dimethylester an cyclische Enolether und ThioenoletherDiese Arbeit wurde von der Deutschen Forschungsgemeinschaft und dem Fonds der Chemischen Industrie unterstützt.Professor Rolf Huisgen zum 60. Geburtstag gewidmet (1980)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 92 (1980), S. 848-849 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19800921021
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  • 99
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    Bildung von Pyrrolnitrin und 3-(2-Amino-3-chlorphenyl)pyrrol aus 7-ChlortryptophanProfessor Alfred Roedig zum 70. Geburtstag gewidmet (1980)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 92 (1980), S. 855-856 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19800921024
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  • 100
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    Ein kationischer Ethylen(hydrido)iridium(III)-KomplexProfessor Rolf Huisgen zum 60. Geburtstag gewidmet (1980)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 92 (1980), S. 863-863 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19800921030
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