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L‐GLUTAMIC ACID DECARBOXYLASE IN NON‐NEURAL TISSUES OF THE MOUSE
Author(s) -
Drummond R. J.,
Phillips A. T.
Publication year - 1974
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.1471-4159.1974.tb12219.x
Subject(s) - glutamate decarboxylase , carboxy lyases , kidney , biochemistry , nad+ kinase , chemistry , aminooxyacetic acid , glutamic acid , enzyme , specific activity , dehydrogenase , microbiology and biotechnology , biology , endocrinology , amino acid
— Low levels of γ‐aminobutyric acid (GABA) and of glutamic acid decarboxylase (GAD) activity have been detected in mouse kidney, liver, spleen and pancreas. Quantitation of both 14 CO 2 and [ 14 C]GABA produced in radiometric assays from [U‐ 14 CJglutamic acid has shown that measurement of 14 CO 2 evolution alone is not, in all cases, a valid estimate of true GAD activity. As evidenced by increased ,14 CO 2 production upon addition of NAD and CoA to assay mixtures, radiometric assay of GAD activity in crude homogenates may yield 14 CO 2 via the coupled reactions of glutamic acid dehydrogenase and a‐ketoglutarate dehydrogenase. The addition of 1 mM aminooxyacetic acid (AOAA) to assays of kidney homogenates inhibited [ ,14 C]GABA production 92 per cent while 14 CO 2 production was inhibited only 53 per cent. No evidence was found to confirm the reported existence of a second form of the enzyme, GAD II. previously described by Haber el al. (H aber B., K uriyama K. & R oberts E. (1970) Biochem. Pharmac. 19, 1119‐1136). Based on sensitivity‐to AOAA and chloride inhibition, the GAD activity in mouse kidney is. apparently, indistinguishable from that of neural origin.