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Stereochemistry of an α,β‐elimination reaction by D‐glucosaminate dehydratase
Author(s) -
Iwamoto Ryoko,
Imanaga Yujiro,
Sawada Seiji,
Soda Kenji
Publication year - 1983
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(83)80242-7
Subject(s) - chemistry , pyranose , deuterium , dehydratase , proton , substrate (aquarium) , dehydration , stereochemistry , coupling constant , reaction rate constant , enzyme , kinetics , organic chemistry , biochemistry , physics , oceanography , particle physics , quantum mechanics , geology
The proton NMR analysis of D‐glucosaminate dehydratase reaction in D 2 O revealed the incorporation of a deuterium atom at C‐3 carbon of the product, 2‐keto‐3‐deoxy‐D‐gluconate. Based on the chemical shift of C‐3 proton of the product and the coupling constant characteristic for the C‐3 and C‐4 axial‐axial coupling in the 2 C 5 pyranose conformation, the deuterium is in the pro‐S position. Thus, the dehydration of D‐glucosaminate by the enzyme proceeds in a retention mode at C‐3 carbon. Kinetic parameters show that the rate‐determining step is the abstraction of α‐proton from the substrate.