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  • Chemistry  (114)
  • Atomic, Molecular and Optical Physics  (11)
  • Gonadotropin  (4)
  • Methanol  (3)
  • Magnetism
  • 1980-1984  (61)
  • 1955-1959  (71)
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Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Regulation of the synthesis of methanol oxidizing enzymes inKloeckera sp. 2201 andHansenula polymorpha, a comparison (1982)
    Springer
    Archives of microbiology 131 (1982), S. 174-175 
    Details
    ISSN: 1432-072X
    Keywords: Hansenula polymorpha ; Kloeckera sp. 2201 ; Methanol ; Glucose ; Methanol dissimilating enzymes ; Regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparative study was made of the regulation of the synthesis of methanol dissimilating enzymes inkloeckera sp. 2201 andHansenula polymorpha using chemostat and batch growth conditions and methanol or glucose as carbon sources. During growth in methanol-limited chemostat cultures similar enzyme patterns for alcohol oxidase, catalase, formaldehyde dehydrogenase and formate dehydrogenase in the two yeasts were found. When growing in batch culture with glucoseH. polymorpha, but notKloeckera sp. 2201, was found to produce ethanol which might affect the synthesis of these enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01054002
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  • 2
    Electronic Resource
    Electronic Resource
    Active-site α-helix in papain and the stability of the ion pair RS- ··· ImH+. Ab initio molecular orbital study (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 651-671 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ab initio MO calculations, using both minimal (STO-3G) and extended (Roos-Siegbahn) basis sets are reported for the systems methanethiol-imidazole, methanethiol-imidazole-formaldehyde, and methanethiol-imidazole-formamide, which, together with a point-change representation of a long α-helix, form models for the active site of papain. It is shown that the large electric field exerted by the helix in the active-site region is responsible for the presence of the essential residues Cys 25 and His 159 in the form of an ion pair RS- ··· ImH+, which is crucial for a recently proposed mechanism for the catalytic action of the enzyme. Also, an explanation is given for the anomalies in measured pK values for these residues. Detailed studies on the (sub)systems show that minimal basis sets lack the flexibility necessary for describing the type of proton transfer involved. We conclude that α-helices are essential parts of enzymes and that they play a significant role in the catalytic process.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170407
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  • 3
    Electronic Resource
    Electronic Resource
    The brain-pituitary-gonadal axis in the rainbow trout, Salmo gairdneri: Gonadal hormones and the maturation of gonadotropic cells (1982)
    Springer
    Cell & tissue research 225 (1982), S. 45-56 
    Details
    ISSN: 1432-0878
    Keywords: Gonadotropic cells ; Maturation ; Gonadotropin ; Gonadal hormones ; Juvenile trout
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intact and castrated juvenile male rainbow trout (Salmo gairdneri) were treated with testosterone and gonadotropic hormone (GTH) to determine the maturational effects of these hormones on the GTH-cells. Electron-microscopic studies of the GTH-cells revealed that GTH and testosterone in intact animals, and testosterone in castrated fish, caused GTH-cell maturation: These cells now displayed the same appearance as GTH-cells in adult trout, including the presence of globules, a well-developed Golgi apparatus and rough endoplasmic reticulum, all of which were absent in GTH-cells of control animals. Animals with stimulated GTH-cells also had an increased GTH content of the pituitary; release of GTH could not be demonstrated. Animals treated with GTH exhibited an accelerated development of the testes, resulting in complete gametogenesis and elevated plasma testosterone levels. These results indicate that exogenous steroids as well as endogenous gonadal steroids can stimulate the full development of GTH-cells and accelerate GTH synthesis. The significance of this stimulating effect of the gonadal hormones with respect to the development of the brain-pituitary-gonadal axis and the onset of puberty is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00216217
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  • 4
    Electronic Resource
    Electronic Resource
    Mixed substrate growth of methylotrophic yeasts in chemostat culture: Influence of the dilution rate on the utilisation of a mixture of glucose and methanol (1982)
    Springer
    Archives of microbiology 131 (1982), S. 8-13 
    Details
    ISSN: 1432-072X
    Keywords: Hansenula polymorpha ; Kloeckera sp. 2201 ; Mixed substrate utilisation ; Chemostat ; Induction ; Repression ; Methanol ; Glucose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The growth of Hansenula polymorpha and Kloeckera sp. 2201 with a mixture of glucose and methanol (38.8%/61.2%, w/w) and the regulation of the methanol dissimilating enzymes alcohol oxidase, catalase, formaldehyde dehydrogenase and formate dehydrogenase were studied in chemostat culture, as a function of the dilution rate. Both organisms utilized and assimilated glucose and methanol simultaneously up to dilution rates of 0.30 h-1 (H. polymorpha) and 0.26h-1, respectively (Kloeckera sp. 2201) which significantly exceeded μmax found for the two yeasts with methanol as the only source of carbon. At higher dilution rates methanol utilisation ceased and only glucose was assimilated. Over the whole range of mixed-substrate growth both carbon sources were assimilated with the same efficiency as during growth with glucose or methanol alone. In cultures of H. polymorpha, however, the growth yield for glucose was lowered by the unmetabolized methanol at high dilution rates. During growth on both carbon sources the repression of the synthesis of all catabolic methanol enzymes which is normally caused by glucose was overcome by the inductive effect of the simultaneously fed methanol. In both organisms the synthesis of alcohol oxidase was found to be regulated differently as compared to catalase, formaldehyde and formate dehydrogenase. Whereas increasing repression of the synthesis of alcohol oxidase was found with increasing dilution rates as indicated by gradually decreasing specific activities of this enzyme in cell-free extracts, the specific activities of this enzyme in cell-free extracts, the specific activities of catalase and the dehydrogenases increased with increasing growth rates until repression started. The results indicate similar patterns of the regulation of the synthesis of methanol dissimilating enzymes in different methylotrophic yeasts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00451491
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  • 5
    Electronic Resource
    Electronic Resource
    Regulatory flexibility of methylotrophic yeasts in chemostat cultures: Simultaneous assimilation of glucose and methanol at a fixed dilution rate (1982)
    Springer
    Archives of microbiology 131 (1982), S. 1-7 
    Details
    ISSN: 1432-072X
    Keywords: Hansenula polymorpha ; Kloeckera sp. 2201 ; Chemostat ; Mixed substrates ; Glucose ; Methanol ; Growth yields ; Enzyme regulation ; Dissimilatory enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of the composition of methanol/glucose-mixtures as only sources of carbon and energy on growth and regulation of the synthesis of enzymes involved in methanol-dissimilation was studied under chemostat conditions at a fixed dilution rate with the methylotrophic yeasts Hansenula polymorpha and Kloeckera sp. 2201. Both carbon sources were found to be utilized completely independently of the composition of the C1/C6 mixture. Using mixtures of 14C-labelled methanol and glucose the growth yield for glucose was found to be constant for all C1/C6-mixtures tested and both yeasts. The growth yield for methanol, however, was reduced by up to 25% when the proportion of methanol in the inflowing medium was lower than 20% (w/w with respect to glucose) for H. polymorpha and 50% (w/w with respect to glucose) for Kloeckera sp. 2201 respectively. During growth with C1/C6-mixtures containing higher C1-proportions of methanol regular growth yields for methanol were recorded which corresponded to the growth yields found with methanol as the only carbon source. The regulation of the synthesis of the enzymes of the dissimilatory pathway for methanol was found to be under multiple control. Although glucose was present in the medium methanol had a positive effect on the synthesis of these enzymes. Thus, in addition to derepression induction by methanol was also observed. This inductive effect was found to increase with increasing proportions of methanol in the mixture. Depending on the enzyme, 10–40% methanol in the mixture resulted in a maximal induction with enzyme specific activities equal to those found in cells grown with methanol as the only carbon source. No further enhancements in enzyme specific activities were observed during growth on mixtures containing more than 40% methanol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00451490
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  • 6
    Electronic Resource
    Electronic Resource
    Accumulation of glycoprotein gonadotropin in the pituitary of juvenile rainbow trout in response to androgens and C21-steroids, including 11-steroids (1984)
    Springer
    Cell & tissue research 235 (1984), S. 635-642 
    Details
    ISSN: 1432-0878
    Keywords: Gonadotropin ; Gonadotropic cells ; Pituitary ; Steroid hormones ; Teleosts (trout)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Effects of steroids on the accumulation of glycoprotein gonadotropin (GTH) in pituitaries of juvenile trout were investigated by means of scanning cytophotometry applied to immunocytochemical preparations, and with the use of a radioimmunoassay. Effects on other aspects of GTH-cell activity were analyzed by measuring the size of the gonadotrops and their nuclei. Progesterone added to aquarium water and methyltestosterone incorporated into the food showed a pronounced stimulatory effect on the accumulation of GTH. To a lesser extent, treatment with cortisol, cortisone, and desoxycorticosterone acetate administered to aquarium water, and 11β-hydroxy-androstenedione added to the food resulted in an increase of the hypophysial content of GTH. Steroids stimulating the accumulation of GTH in the pituitary also exhibited a positive effect on GTH-cell activity as indicated by an increase in the size of gonadotropic cells. Progesterone incorporated into the food did not influence the GTH-content and the GTH-cell activity. It is suggested that the route of administration of an exogenous steroid is essential for its effect on GTH cells in trout. Comparison of GTH values reveals an excellent correlation between the data from the radioimmunoassay and those from the corresponding densitometric measurements. No correlation was observed between values of morphometrically determined GTH-cell activity and the densitometric values reflecting hypophysial GTH content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226962
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  • 7
    Electronic Resource
    Electronic Resource
    Wasser. Lösungsmittel, Lebensraum und Ökofaktor. Von R. Wittig. Akademische Verlagsgesellschaft, Wiesbaden 1979. VIII, 184 S., Zeichn. u. Tab., kart. DM 24, - (1980)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 14 (1980), S. 103-103 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19800140306
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  • 8
    Electronic Resource
    Electronic Resource
    Calculation of systems involving strong delocalized bonds within a modified PCILO framework. I. Valence-bond PCILO method (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 475-481 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In describing mesomer structures by the original PCILO method several problems may occur because of the use of localized bonds. A so-called VB-PCILO including a superposition of several mesomer boundary structures in the CI perturbation treatment will be proposed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250303
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  • 9
    Electronic Resource
    Electronic Resource
    A modified PCILO framework using the CNDO/Boyd-Whitehead parametrization (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 25 (1984), S. 1055-1060 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The CNDO/BW modification of the CNDO/2 approximation was used within the PCILO framework. It was shown on some significant examples that all the good results of the original PCILO-CNDO/2 method can be reproduced by the modified version PCILO-CNDO/BW at least. Thus, preserving the quality of its results a computer-expense-reduced PCILO method is proposed for calculations on large molecular systems.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560250610
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  • 10
    Electronic Resource
    Electronic Resource
    Many-electron theory of autoionizing states using complex coordinates: The position and the partial and total widths of the Ne+ 1s hole state (1984)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 26 (1984), S. 1017-1027 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article presents the first results of the application of quantum mechanics with complex coordinates to the calculation of partial widths for the radiationless decay of an inner-hole excited autoionizing state, the Ne+1s2s22p6 2S. This is succeeded by the reduction of the multi-electron, multichannel problem in the complex energy plane to five, symmetry adapted, two-electron problems, in accordance with a published theory of many-electron resonances. These two-electron problems are solved independently by using rotated analytic Hartree-Fock orbitals (expressed in terms of Slater orbitals) for the localized components, and Slater plus Gamow orbitals for the rotated, asymptotic square-integrable functions carrying the width information. A recently proposed variational principle is employed for the optimization of nonlinear parameters. Within this independent asymptotic pair approximation (IAPA), our results for the partial widths to the five Ne2+ channels are (in 10-2 a.u.): 1s-2p2 1D: 0.560, 1S: 0.048; 1s-2s2p, 3P0: 0.029, 1P0: 0.154; 1s-2s2, 1S: 0.044. The total width is 0.835. These numbers agree reasonably well with those obtained by Kelly [Phys. Rev. A 11, 556 (1975)] from a many-body perturbation theory (MBPT) calculation, and by Howat et al. [J. Phys. B 11, 1575 (1978)] from a configuration-interaction in the continuum calculation. The most recent experimental results yield 0.604, 0.089, 0.063, 0.174, and 0.060, respectively, with a total width of 0.99. Previous real-coordinate many-electron calculations by Beck and Nicolaides-including relativistic and radiative effects-have predicted the position of the Ne+ 1s hole state at E0 = 870.4 eV above the Ne ground state. It has already been shown that the real energy corresponding to the localized component of the autoionizing state is stable under rotations of the function space describing it. Therefore, the earlier E0 can be incorporated into the present calculation in the complex plane. The shift due to the additive contribution of the IAPA is found to be - 0.09 eV. When this is added to E0, the final E = 870.3 eV is in excellent agreement with experiment [870.3 eV; T. D. Thomas and R. W. Shaw, Jr., J. Electron. Spectrosc. Relat. Phenom. 8, 45 (1976)].
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560260606
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