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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 779-790 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: X-ray diffraction and stereochemical analyses were used to study the hydrated structure of the helical amylose polymorph having a fiber repeat spacing of 8 Å. Intensity calculations using computer models confirmed six as the number of residues per turn and supported the space group P212121. Both diffraction intensity and stereochemical methods indicate the suitability of residue G3 from the potassium acetate complex of cyclohexaamylose as opposed to residues with longer O(4)-O(1) vectors. Comparison of the present results with those obtained for V amylose dehydrate indicated no major conformational differences between the two helix skeletons. A net helical rotation of approximately 30° accompanied the hydrate-dehydrate transition and the rotational position in the hydrate allowed packing that was less close. Hydration water molecules were not located; noncarbohydrate peaks on the electron density maps were primarily due to Fourier series termination errors.
    Additional Material: 4 Ill.
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  • 2
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Although native B-type starch loses its sharp X-ray pattern on strong drying, the wet Nägeli amylodextrin prepared from such starch gives a sharp B-pattern, that is only slightly reduced in sharpness by complete drying. Nägeli amylodextrin dried admixed with a noncrystalline “filler” (e.g., starch sirup) gives an X-ray pattern essentially identical to that of the wet amylodextrin, except that the 16-Å (No. 1) ring is greatly reduced in sharpness and intensity. Failure of the B-structure to collapse during drying indicates that water is not intercalated between turns of a helix or otherwise required to maintain the geometry and packing arrangement of the starch molecular chains. Rather, for native starch granules or amylose fibers, water relieves intercrystallite strains and consequent crystallite distortion induced by strong drying. For Nägeli amylodextrin, the small molecules of starch sirup can penetrate the interstices between crystallites and prevent strain build-up during drying. For native starch granules, the interstitial regions are gel-like in character and less permeable to starch sirup molecules. A model for B-starch is proposed, that employs intertwined (double) helices.
    Additional Material: 13 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 16 (1974), S. 869-880 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Conventional sources of protein cannot meet the present or projected needs for human consumption. Single cell proteins from fermentation of petroleum and cellulosic wastes are likely sources of additional protein. The volume of cellulosic wastes is sufficient to supply all additional protein needs on a continuing basis for cellulose is a renewable resource. Both mesophilic and thermophilic microorganisms utilize cellulose at reasonable rates. Biodegradation of lignin and lignin-cellulose complexes constitutes a major obstacle to commercial utilization of cellulosic wastes. Thermophilic actinomyces appear to be the most effective organisms for single cell protein production from cellulosic wastes.
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  • 4
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nägeli-type amylodextrins were prepared from various starch types: native starch granules from potato, waxy maize, wrinkled pea, and high-amylose maize, and from a commercial amylose (“Superlose”). The granular starches and retrograded amylose were treated with 15% sulfuric acid at 22°-25° for 3 months, the undissolved residues were washed free of acid and air dried. X-ray diffraction patterns showed that amylodextrin from waxy maize starch (A-type) and potato starch (B-type) retain the same diffraction type as that of the parent starch. On conversion of a starch to an amylodextrin, the sharpness and intensity of the diffraction patterns are either retained (waxy maize starch), improved (slightly with potato, significantly with high-amylose maize, and very markedly with wrinkled pea) or developed (amylose). The results indicate that the crystalline regions of a native starch granule, retrograded amylose, or amylodextrin are exceedingly resistant to acidic hydrolysis at room temperature. In contrast to the parent starches, native amylodextrins stain little if at all with dilute iodine solution. The iodine stains of dissolved amylodextrins were red (waxy maize), red-purple (potato), or purple (amylose, high-amylose maize, and wrinkled pea).
    Additional Material: 5 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 201-221 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Theoretical calculations of the circular dichroism of double-helical DNA and RNA by the method of Johnson and Tinoco were performed in order to investigate the origins of the optical activity spectral differences between these polynucleotides. Calculations were performed using transition moment directions arising from molecular orbital calculations as well as a transition moment directions in agreement with experimental directions. The results of these calculations indicate that the conservative circular dichroism spectrum of B-form DNA and the nonconservative spectrum of RNA (and A-form DNA) arise as a consequence of the distance between the paired bases and the helix axis. The negative nonconservative spectrum of C-form DNA was calculated and shown also to result from the distance of the paired bases from the helix axis. Several other conspicuous geometric parameters of DNA and RNA were investigated and were found to be less significant in their effects upon the spectral differences. Theoretical calculations on a four-stranded DNA model which has paired bases similarly related to the helix axis as RNA and A-form DNA was found to yield a low intensity, nonconservative circular dichroism spectrum.
    Additional Material: 12 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1487-1501 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Visually integrated, flat-plate film data were collected from oriented filaments of V amylose dehydrated made from dimethyl sulfoxide-amylose; and X-ray diffraction and stereochemical methods were used to search a multidimensional parameter space for the most satisfactory description of the crystal and molecular structure. Results indicate that the helical chains are left-handed and that they pack into the unit cell in an antiparallel arrangement conforming to space group P212121. Packing is very compact with several O …. O contacts in the range 2.70-2.85 Å between both parallel and antiparallel pairs of chains. Other characteristics of the final model are residue geometry similarity to residue 3 from potassium acetate-cyclohexamylose, O(2)i-O(3)i+1 distance of 2.75 Å, O(6) gg, and O(6)i-O(2)i-6 distance of 2.84 Å. Proton magnetic resonance studies of dried, crystalline V amylose dehydrate powder showed only 0.15 water per glucose residue.
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 977-986 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Theoretical calculations of the near ultraviolet (uv) circular dichroism of double-helical DNA and RNA models were performed in order to evaluate the effects, on the calculated circular dichroism, of including the interactions of near uv quantum transitions of the nucleic acid bases with classical polarizable bonds of the sugar-phosphate backbone. Double-helical models (A-form, B-form, and C-form DNA and RNA-11) from X-ray diffraction data were used in the calculations. The results indicate that the contributions to the circular dichroism in the near uv region, of these types of interactions, provide calculated spectra that are slightly altered from calculated spectra when only base-base transition interactions were considered.
    Additional Material: 4 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 91 (1977), S. 335-344 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A liquid culture system is described whereby proliferation of haemopoietic stem cells (CFU-S), production of granulocyte precursor cells (CFU-C), and extensive granulopoiesis can be maintained in vitro for several months. Such cultures consist of adherent and non-adherent populations of cells. The adherent population contains phagocytic mononuclear cells, “epithelial” cells, and “giant fat” cells. The latter appear to be particularly important for stem cell maintenance and furthermore there is a strong tendency for maturing granulocytes to selectively cluster in and around areas of “giant fat” cell aggregations. By “feeding” the cultures at weekly intervals, between 10 to 15 “population doublings” of functionally normal CFU-S regularly occurs. Increased “population doublings” may be obtained by feeding twice weekly. The cultures show initially extensive granulopoiesis followed, in a majority of cases, by an accumulation of blast cells. Eventually both blast cells and granulocytes decline and the cultures contain predominantly phagocytic mononuclear cells.Culturing at 33°C leads to the development of a more profuse growth of adherent cells and these cultures show better maintenance of stem cells and increased cell density.When tested for colony stimulating activity (CSA) the cultures were uniformly negative. Addition of exogenous CSA caused a rapid decline in stem cells, reduced granulopoiesis and an accumulation of phagocytic mononuclear cells.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 82 (1973), S. 461-473 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A liquid culture system, for haemopoietic cells, has been developed using bone marrow cells alone, or co-cultures of thymus and bone marrow cells, inoculated into four ounce medical bottles. After several days growth, such cultures consisted of an attaching population of cells, forming discrete colonies, and a non-attaching population. In the (co-cultures) there was a 2 X enhancement of monolayer colony development compared with the combined total present in the (marrow alone) plus (thymus alone) cultures. Also, better maintenance of non-attaching cells was seen in the (co-cultures). Normal CFUS and CFUC were present in both the (marrow alone) and the (co-cultures) for at least 14 days.In the (marrow alone) cultures, granulocytes in all stages of development were present for the first week, but by 12 days the culture consisted mainly of mono-nuclear cells. In the (co-cultures), however, at 12 days more than 60% of the cells were granulocytes, in all stages of differentiation. (Co-cultures) established using lethally irradiated thymus cells were not able to support this prolonged myeloid differentiation.By feeding the (co-cultures) it was possible to maintain production of (granulocytic) cells for at least ten weeks, although no fully mature granulocytes were observed. After the second feeding, no CFUS were detectable, but variable numbers of agar colony forming cells (not classical CFUC) were present at least for ten weeks.
    Additional Material: 10 Ill.
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  • 10
    Publication Date: 1978-12-01
    Print ISSN: 0304-4203
    Electronic ISSN: 1872-7581
    Topics: Geosciences
    Published by Elsevier
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