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  • Theoretical conformational analysis  (1)
  • arrhenius plots  (1)
  • 1
    ISSN: 1573-4951
    Keywords: Dipeptidyl-peptidase IV ; ECEPP ; Theoretical conformational analysis ; Recognition conformation ; Catalytic mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary By theoretical conformational investigations of substrates and nonsubstrates of the enzyme dipeptidyl-peptidase IV (DP IV) as well as dipeptide-esters using the ECEPP83 method we determined the structure of peptides recognized and cleaved by the enzyme. From a comparison of all possible structures for the substrates with conformations not possible in nonsubstrates we concluded that a single conformation explains substrate specificities of DP IV. This conformation is characterized by the following dihedral angles: {ie159-1}, {ie159-2}, {ie159-3}, {ie159-4}, and {ie159-5}. The conclusions were supported by comparisons of molecular electrostatic potentials calculated with the molecular graphics program HAMOG.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    ISSN: 1573-904X
    Keywords: 2′,3′,5′-triacetyl-6-azauridine ; prodrug ; hydrolysis ; pH-profile ; arrhenius plots ; CI-MS ; NMR ; liquid chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The purposes were to study the kinetics of hydrolysis of 2′,3′,5′-triacetyl-6-azauridine ( 1 ) in aqueous solution (µ = 0.5) and to identify the main intermediates and products of the reaction. Methods. A stability indicating isocratic LC assay was used to study the rate of degradation of 1 A gradient LC assay was used to study the time courses of the degradants. The products of hydrolysis were isolated by preparative liquid chromatography and identified by 1H-NMR and CI-MS. The pKa value was obtained by potentiometric titration. Results. At 36.8°C, the pH-rate profile of 1 in water was adequately described by a four-term rate equation. The intermediates were identified as the primary and secondary di-acetates, and the primary and secondary mono-acetates. The final product was 6-azauridine. Conclusions. A simplified kinetic scheme could be used to describe the concentration-time profiles of 1, the intermediates and the final product.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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