TRANSAMINATION IN PLANTS: THE SPECIFICITY OF AN AMINOTRANSFERASE FROM MUNG BEAN

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Abstract
A study has been made of the specificity of an aminotransferase from mung bean (Phaseolus aureus Roxb.). The enzyme was purified 40- to 60-fold by using Sephadex G-50, ammonium sulfate precipitation, DEAE-cellulose, and hydroxylapatite. In the presence of pyruvate the enzyme transaminated a number of cyclic and aliphatic amino acids. Some of the better substrates were lysine, arginine, ornithine, glutamine, methionine, leucine, 4-fiuorophenyl-alanine, phenylalanine, tyrosine, tryptophan, 3,4-dihydroxyphenylalanine, and γ-phenylbutyrine. Threonine, serine, and glycine were not transaminated. Lysine, methionine, and glutamate were competitive inhibitors of the transamination of phenylalanine.