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  • 1
    Electronic Resource
    Electronic Resource
    The stereochemical resolution of the enantiomers of aspartame on an immobilized α-chymotrypsin hplc chiral stationary phase: The effect of mobile-phase composition and enzyme activity (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 2 (1990), S. 32-37 
    Details
    ISSN: 0899-0042
    Keywords: aspartame stereoisomers ; chiral separations ; column liquid chromatography ; chymotrypsin on silica ; binding sites ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantioselective and diastereoselective resolutions of the stereoisomers of Nα-aspartyl-phenylalanine 1-methyl ester (APME) have been accomplished on an HPLC chiral stationary phase based upon α-chymotrypsin (the ACHT-CSP) with observed enantioselectivities (α1) for the DL-/LD-enantiomers of as high as 29.17 and for the DD-/LL-enantiomers of as high as 28.97. In addition, the effect on the chromatographic retention of the APME stereoisomers of the activity of the ACHT and the composition of the mobile phase - structure of the anionic component, molarity, and pH - have been studied. The results of this study suggest that the aspartyl moiety and/or the aspartyl-phenylalanine amide linkage play key roles in the observed enantioselectivity; the APME stereoisomers containing L-phenylalanine, i.e., DL- and LL-APME, bind at a different site in the ACHT molecule (the L-Phe site) than the APME stereoisomers containing D-phenylalanine (the D-Phe site); and the observed enantioselectivity is a measure of the difference in the binding affinities at the two sites rather than the consequence of differential affinities at a single site.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530020105
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of specific albumin ligand markers used as modifiers on the separation of benzodiazepine enantiomers by chiral liquid chromatography on a human serum albumin column (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 71-77 
    Details
    ISSN: 0899-0042
    Keywords: chiral stationary phase ; mobile phase modifier ; digoxin ; warfarin ; medium chain fatty acid ; bilirubin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Specific ligand markers for the various binding sites of human serum albumin (HSA) have been described in the literature. Some of these markers (medium chain fatty acids, warfarin, digoxin, and bilirubin) were used as mobile phase modifiers. Using a high performance liquid chromatographic (HPLC) column containing HSA as stationary phase, their influence was investigated on the separation in this phase of the enantiomers of three benzodiazepines (temazepam, oxazepam, and lorazepam). Displacement effects were observed with medium chain fatty acids. This influence was proportional to the chain length and to the concentration of acid. Allosteric cooperative effects were noted with digoxin for the three benzodiazepines. Both displacement and cooperative effects were observed with warfarin. Stereoselectivity was decreased for temazepam and oxazepam and increased for lorazepam. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050206
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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