Mechanism of Action of Urocanase: Ruling Out a 1,5 Sigmatropic H-Shift in the Intermediate NAD+ Urocanate Adduct
✍ Scribed by C. Schubert; J. Retey
- Book ID
- 102563816
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 140 KB
- Volume
- 22
- Category
- Article
- ISSN
- 0045-2068
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✦ Synopsis
The tightly bound (\mathrm{NAD}^{+})in urocanase forms a covalent adduct with the inhibitor imidazole propionate and most likely also with the substrate urocanate. Subsequent tautomerizations and cleavage of the adduct lead eventually to the product, 5 -hydroxyimidazole propionate. The possibility that the (\mathrm{H} 4) atom of the nicotinamide moiety undergoes a 1,5 sigmatropic (\mathrm{H})-shift in one of the intermediates has been investigated by deuterium labeling. No incorporation of solvent deuterium into position 4 of the nicotinamide moiety could be detected, which rules out a 1,5-sigmatropic shift of the (\mathrm{H} 4) atom. 1994 Academic Press, Inc.