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  • 1
    ISSN: 0899-0042
    Keywords: column liquid chromatography ; chiral separations ; chymotrypsin on silica ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereochemical separation of free and derivatized amino acids on active α-chymotrypsin bonded to silica is governed by two mechanisms based on the structure of the solutes or on the enzymatic activity of the enzyme. Te deactivation of the hydrolytically active site of the enzyme demonstrated that a significant portion of the retention on this support is due to hydrophobic interactions at other sites. These sites appear to be stereoselective for the ester derivatives of amino acids but not for the other studied solutes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
    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
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  • 3
    ISSN: 1573-904X
    Keywords: warfarin enantiomers ; achiral/chiral high-performance liquid chromatography (HPLC) ; enantioselective HPLC ; serum levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An assay for the serum concentration of the enantiomers of warfarin, R-warfarin and S-warfarin, has been developed using a bovine serum albumin chiral stationary phase (BSA-CSP) coupled to a Pinkerton internal-surface reverse-phase (ISRP) achiral column. The ISRP column is used to separate R,S-warfarin from the serum components and warfarin metabolites and to quantitate the total R,S-warfarin concentration. The eluent containing R,S-warfarin is then selectively transferred to the BSA-CSP, where the enantiomers are stereochemically resolved (α = 1.19) and the enantiomeric composition is determined. This system is sensitive and accurate, does not require extensive precolumn manipulations, and can be automated for use in large-scale clinical studies.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0899-0042
    Keywords: amylose tris-3,5-dimethylphenyl carbamate CSP {AD-CSP} ; cellulose tris-3,5-dimethylphenyl carbamate CSP {ODH-CSP} ; enantioselective HPLC ; coupled column chromatography ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantioselective HPLC methods have been developed for the resolution of (RS)-2-phenylcyclohexanone (compound 1) and (RS)-2-phenyltetrahydropyran-4-one (compound 4) and the diastereoselective and enantioselective separations of their respective cis- and trans-alcohols; reduction of compound 1 yields trans- and cis-2-phenyl-1-cyclohexanol (compounds 2 and 3, respectively) and reduction of compound 4 yields trans- and cis-2-phenyl-tetrahydropyran-4-ol (compounds 5 and 6, respectively). Compounds 1, 2, and 3 were stereochemically resolved using a chiral stationary phase (CSP) based upon amylose tris(3,5-dimethylphenyl carbamate) coated on 10 μm silica-gel (Chiralpak AD-CSP). Compounds 4, 5, and 6 were stereochemically resolved on a coupled column system where a column containing a CSP based upon cellulose tris(3,5-dimethylphenyl carbamate) coated on 5 μm silica (Chiralcel OD-H-CSP) was coupled in series to the AD-CSP. The strategy employed in the identification of the peaks in the respective chromatograms is also discussed in this presentation. Chirality 8:551-555, 1996. © 1997 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 9 (1997), S. 96-98 
    ISSN: 0899-0042
    Keywords: enantioselectivity ; stereospecificity ; chiral separations ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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