Amine Transaminase

An enzyme “amine transaminase”, which catalyzed transamination between amines and α-keto acids, was found to occur in certain fermentative bacteria, such as Escherichia coli and Aerobacter aerogenes. Using a partially purified enzyme preparation obtained from cell extract of E. coli, some properties of the enzyme were investigated. α-Ketoglutaric acid appeared to be the most efficient amino acceptor and substitution of α-ketoglutaric acid by other α-keto acid resulted in much lower activity. Putrescine, cadaverine and hexamethylenediamine were found to be active as amino donors, but the other monoamines, diamines and polyamines were inert. Treatment of the enzyme with acid ammonium sulfate resolved the enzyme into apo- and coenzyme. The apoenzyme was well reactivated by pyridoxal phosphate as well as pyridoxamine phosphate. Physiological role of the amine transaminase was suggested in relation to the metabolism of amines in bacterial cells.