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Regulation and Properties of an NADP + Oxidoreductase Which Functions as a γ‐Hydroxybutyrate Dehydrogenase
Author(s) -
Kaufman E. E.,
Relkin N.,
Nelson T.
Publication year - 1983
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1983.tb08137.x
Subject(s) - dithiothreitol , oxidoreductase , glucuronate , chemistry , dehydrogenase , enzyme , oxidizing agent , biochemistry , glutathione , substrate (aquarium) , nad+ kinase , stereochemistry , organic chemistry , biology , ecology
A number of naturally occurring biological intermediates have been found to inhibit competitively the activity of a highly purified NADP + ‐dependent oxidore‐ductase which catalyzes the simultaneous oxidation of γ‐hydroxybutyrate to succinic semialdehyde, and the reduction of D‐glucuronate to L‐gulonate. Of the inhibitors studied, those with the lowest K i are the α‐keto analogues of the branched chain or aromatic amino acids. The V max and K m for this enzyme are affected by pH; consequently, changes in substrate concentration can markedly alter the pH optimum. The enzyme has been found to be inhibited by reducing agents such as dithiothreitol and mercapto‐ethanol, protected against this inhibition by oxidizing agents such as oxidized glutathione or H 2 O 2 , and finally, protected against heat inactivation by the presence of either NADP + or NADPH.