- - g. acetyltransferase 1. an enzyme catalyzing transfer of an acetyl group from N2-acetylornithine to l-g. forming l-ornithine and N-acetyl-l-g., an activator of the urea cycle; 2. an enzyme that catalyzes the transfer of an acetyl group from acetyl-CoA to l-g. to form coenzyme A and N-acetyl-L-g., which is an activator of the urea cycle. SYN: ornithine acetyltransferase.- g. decarboxylase (GAD) a carboxy-lyase converting l-g. to 4-aminobutyrate and CO2 as well as l-aspartate to 3-aminopropanoate and CO2; a defect in the binding of this protein's coenzyme is believed to be the cause of pyridoxine dependency with seizures. SYN: aspartate 1-decarboxylase.- g. dehydrogenases enzymes that catalyze the reaction of l-g., H2O, and NAD+ (or NADP+ in some cases) producing α-ketoglutarate (2-oxoglutarate), ammonia, and NADH; in mammals, this is the prime contributor to oxidative deamination. SYN: glutamic acid dehydrogenases.- g. formiminotransferase an enzyme that catalyzes the transfer of the formimino moiety of N-formimino-l-g. to tetrahydrofolate; a deficiency of this enzyme will lead to elevated formiminoglutamate levels.- g. γ-semialdehyde an intermediate in l-proline and l-ornithine metabolism; becomes elevated in type II hyperprolinemia.- g. synthase an enzyme that converts l-glutamine, α-ketoglutarate, and NADH (in some cases, NADPH) to two l- glutamates and NAD+ (or NADP+); apparently, a nonmammalian enzyme. In some plants this is a ferredoxin-dependent reaction.
* * *glu·ta·mate 'glüt-ə-.māt n a salt or ester of glutamic acid specif a salt or ester of levorotatory glutamic acid that functions as an excitatory neurotransmitter see MONOSODIUM GLUTAMATE
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* * *glu·ta·mate (glooґtə-māt) a salt, ester, or anionic form of glutamic acid; glutamate is the principal excitatory neurotransmitter in the central nervous system.
Medical dictionary. 2011.