On the Mechanism of Action of Urocanase: Observation of the Enzyme-Bound NAD+ -Inhibitor Adduct by 13C NMR Spectroscopy

Authors

  • Dr. Carsten Schubert,

    1. Institut für Organische Chemie der Universität Richard-Willstätter-Allee, D-76128 Karlsruhe (Germany) Telefax: Int. code + (721)608-4823
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  • Dr. Herbert Röttele,

    1. Institut für Organische Chemie der Universität Richard-Willstätter-Allee, D-76128 Karlsruhe (Germany) Telefax: Int. code + (721)608-4823
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  • Dr. Manfred Spraul,

    1. Bruker Analytische Meßtechnik GmbH D-76287 Rheinstetten (Germany)
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  • Prof. Dr. János Rétey

    Corresponding author
    1. Institut für Organische Chemie der Universität Richard-Willstätter-Allee, D-76128 Karlsruhe (Germany) Telefax: Int. code + (721)608-4823
    • Institut für Organische Chemie der Universität Richard-Willstätter-Allee, D-76128 Karlsruhe (Germany) Telefax: Int. code + (721)608-4823
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  • Generous financial support by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie is acknowledged. We thank Ms. J. Herman for numerous enzyme isolations.

Abstract

original image

Not the aromatic form 1 a but the nonaromatic form 1b of the enzyme-inhibitor complex is preferred at the active site of urocanase. This can be observed in situ with 13C-labeled components by NMR spectroscopy. The enzyme-bound adducts were characterized by use of (4-13C)NAD+-containing urocanase and the labeled inhibitor (5′-13C)imidazolepropionate. • = 13C, R = adenosine diphosphate ribosyl.

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