ISOLATION, ENZYME-PRODUCTION AND CHARACTERIZATION OF D-ASPARTATE OXIDASE FROM FUSARIUM-SACCHARI VAR ELONGATUM Y-105

A microorganism that produces D-aspartate-oxidizing enzyme by inductio n was isolated from soil, and identified as Fusarium sacchari var. elo ngatum Y-105. The enzyme catalyzed the oxidative deamination of D-aspa rtate (D-Asp) and produced oxaloacetate, ammonia, and hydrogen peroxid e, stoichiometrically. The enzyme is designated ''D-Asp oxidase'' (EC 1.4.3.1). In addition to D-Asp, the enzyme oxidized D-glutamate (D-Glu ) and N-methyl-D-aspartate (NMDA). N-Acetyl-D-Asp and other D- or L-am ino acids, however, were inert as substrates. The optimum pH and tempe rature were 7.5 and 40 degrees C, respectively. The enzyme was stable at pH9.0 and temperature of 50 degrees C, respectively. The enzyme act ivity was not inhibited by sodium benzoate which is a specific inhibit or of D-amino acid oxidase from mammals. The enzyme activity was also not affected by carboxylates such as meso- or D-tartarate, citrate, an d fumarate which inhibit D-Asp oxidase from rabbits.