Distribution of co-Amino Acid: Pyruvate Transaminase and Aminobutyrate: α-Ketoglutarate Transaminase in Microorganisms

Abstract

The distribution of co-amino acid transaminases in microorganisms was investigated, co-Amino acid: pyruvate transaminase (ι-APT) was found in bacteria and yeasts, but not in actinomycetes and fungi. On the contrary, aminobutyrate: α-ketoglutarate transaminase (GABA-T) was shown in most of the microorganisms from bacteria to fungi.β-β Alanine is a preferred amino donor for the ι-APT reaction. Although bacterial and yeast GABA-T are inactive for β-alanine, fungal and actinomycete enzymes react with this compound and γ-aminobutyrate. In comparing these results with those of plant and mammalian enzymes, two different pathways of ι-amino acid metabolism are suggested for bacteria, yeast and plants, i.e. one for β-alanine and the other for γ-aminobutyrate, catalyzed by ι-APT and GABA-T, respectively. In actinomycetes, fungi, and mammals GABA-T may be involved in the metabolism of both ι-amino acids. In addition, evolutionary changes of ι-amino acid transaminases are discussed. © 1983, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.