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  • Polymer and Materials Science  (2)
  • Solvent structure  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Solvent structure in vitamin B12 coenzyme crystals (1985)
    Springer
    European biophysics journal 11 (1985), S. 225-237 
    Details
    ISSN: 1432-1017
    Keywords: Solvent structure ; hydrogen bond networks ; computer simulation ; B12 coenzyme crystals ; probability density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Both the ordered and disordered solvent networks of vitamin B12 coenzyme crystal hydrate have been generated by Monte Carlo simulation techniques. Several different potential functions have been use to model both water-water and water-solute (i.e., water-coenzyme) interactions. The results have been analysed in terms of the structural properties of the water networks, such as mean water oxygen and hydrogen positions, coordination of each water molecule, and maxima of probability density maps in all four asymmetric units of this crystal. The following results were found: (I) Within each asymmetric unit only one hydrogen bonding network was predicted although there were several hydrogen atom positions for any one solvent molecule (defined as maxima in probability density). (II) Reasonable agreement was obtained between predicted and experimental positions in the ordered solvent region, independent of the potential function used. (III) The positions of the calculated probability density maxima for the disordered channel region were different in different asymmetric units; this led to different simulated hydrogen bond networks which were not always consistent with the experimentally determined alternative (lower occupancy) sites. The results suggest that it is advisable to simulate more than one asymmetric unit if one wishes to look at disorder in the solvent regions. Probability density maps were qualitatively very useful for picturing these disordered regions. However, there were no significant differences between quantitative results predicted using either average atomic positions or maxima of the probability density distributions. Problems in quantifying agreement between experimental and predicted disordered solvent networks are discussed. The potential which included hydrogen atoms explicitly (EMPWI) seemed to give the best overall agreement, mainly because it was successful in predicting the unusually short hydrogen bonds which are found in this crystal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00261999
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Sequential hydration of a dry globular protein (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 255-260 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using direct difference ir and laser Raman spectroscopy, the sequential hydration of hen egg-white lysozyme was monitored. The ir data allowed us to identify some specific molecular hydration events that occur as water is added, whereas the Raman is interpreted in terms of conformational changes. The largest of these solvent-induced changes occurs below the hydration level at which activity commences.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220135
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Sequential hydration of dry proteins: A direct difference IR investigation of sequence homologs lysozyme and α-lactalbumin (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 1647-1666 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Direct difference ir spectra are presented as a function of hydration for lysozyme and α-lactalbumin, and detailed sequential hydration molecular events identified. Despite the strong sequence homology between the two proteins, and their expected conformational similarity, the hydration behaviour of the polar groups is different for the two proteins. Using a Hill-type analysis, we conclude that the acid groups ionize and hydrate rapidly and noncooperatively in both proteins, consistent with the known (lysozyme) and postulated (α-lactalbumin) surface chemistry. The polar group hydration shows a clear cooperativity, which is quantitatively different in the two proteins. Complementary work suggests this cooperativity relates to a hydration-induced “loosening up” of the lysozyme conformation at about 55 mol water/mol protein. α-Lactalbumin appears to “open up” more easily for hydration than does lysozyme, consistent with its lower stability against thermal and acid denaturation.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360230904
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    Paper (German National Licenses)
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