Evidence for Participation of Vit. B6 in Glutamine-a-Keto Acid Transamination-Deamidation Reaction

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Abstract
Liver homogenates prepared from rats given large doses of isonicotinic acid hydrazide (INAH) exhibited reduced glutamine-pyruvate transaminase-deamidase activity and increased glutaminase activity. Purified enzyme preparations (free of glutaminase) prepared from livers of INAH-treated rats catalyzed the glutamine-pyruvate reaction at markedly reduced rates compared to controls. Addition of pyridoxal (or pyridox-amine) phosphate produced a considerable increase in activity of the preparations obtained from INAH-treated rats, but not of that of the untreated controls. The evidence supports the concept that vitamin B6 participates in the glutamine transaminase system.