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Succinic Semialdehyde as a Substrate for the Formation of γ‐Aminobutyric Acid
Author(s) -
Bemmelen F. J.,
Schouten M. J.,
Fekkes D.,
Bruinvels J.
Publication year - 1985
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.1471-4159.1985.tb07214.x
Subject(s) - gaba transaminase , succinic acid , aminobutyric acid , glutamate decarboxylase , substrate (aquarium) , chemistry , transaminase , cofactor , glutamate receptor , biochemistry , gamma aminobutyric acid , limiting , stereochemistry , enzyme , biology , mechanical engineering , ecology , receptor , engineering
The conversion of succinic semialdehyde into γ‐aminobutyric acid (GABA) by GABA‐transaminase was measured in rat brain homogenate in the presence of different concentrations of the cosubstrate glutamate. The calculated kinetic parameters of succinic semialdehyde for GABA‐transaminase were a limiting K m value of 168 μ M and a limiting V max value of 38 μmol g −1 h −1 . Combination with previously obtained data for the conversion of GABA into succinic semialdehyde revealed a kEq value of 0.04, indicating that equilibrium of GABAtransaminase is biased toward the formation of GABA. The increased formation of GABA in the presence of succinic semialdehyde was not due to an increased conversion of glutamate into GABA by glutamic acid decarboxylase. Therefore these results indicate that succinic semialdehyde can act as a precursor for GABA synthesis.