Induction of the D-amino acid oxidase from Trigonopsis variabilis

Induction of the D-amino acid oxidase (EC. 1.4.3.3) from the yeast Trigonopsis variabilis was investigated by using a minimal medium containing glucose as the carbon and energy source, (NH4)(2)SO4 as the nitrogen source, and various D- and DL-amino acid derivatives as inducers. The best new inducers found were N-carbamoyl-D-alanine, N-acetyl-D-tryptophan, and N-chloroacetyl-D-alpha-aminobutyric acid; when the induction effects of these compounds were compared with the effects of D-alanine as the nitrogen source and inducer, the resulting activities of D-amino acid oxidase per gram of dried yeast were 4.2, 2.1, and 1.5 times higher, respectively. The optimum concentration of the best inducer, N-carbamoyl-D-alanine, was 5 mM. This inducer could also be used in its racemic form. The induction was pH dependent. After cultivation of the yeast in a 50-liter bioreactor, D-amino acid oxidase activity of about 3,850 mu kat (231,000 U) was obtained. In addition, production of the D-amino acid oxidase was found to be significantly dependent on the metal salt composition of the medium. Addition of zinc ions was required to obtain high D-amino acid oxidase levels in the cells, The optimum concentration of ZnSO4 was about 140 mu M.