Aminotransferase activities in Trichomonas vaginalis

A survey of aminotransferase activities present in a cell-free extract of the anaerobic protozoan, Trichomonas vaginalis was performed. 2-Oxoglutarate, oxaloacetate or phenylpyruvate acted as effective amino acceptors with tyrosine, phenylalanine, tryptophan, leucine, valine, isoleucine, aspartate, alanine, ornithine or lysine. Arginine, serine, glutamine, glycine, beta-alanine and gamma-aminobutyrate were not active as amino donors. With pyruvate as acceptor, significant, yet low, activity was seen only with glutamate, lysine or phenylalanine. Partial purification of enzymes catalysing transamination of leucine, valine, isoleucine, alanine, ornithine and lysine were carried out. A single enzyme catalysed the transamination of ornithine and lysine. The substrate specificity of this enzyme is novel. A separate enzyme catalysed the transamination of all three branched chain amino acids. A third enzyme catalysed the alanine aminotransferase reaction. A fourth enzyme catalysing the transamination both of aromatic amino acids and aspartate has previously been purified [Lowe, P.N. and Rowe, A.F. (1985) Biochem. J. 232, 689-695].