GLYCINE OXIDASE AND SERINE DEHYDRATASE IN GREEN LEAVES OF WHEAT AND MAIZE AND THEIR POSSIBLE ROLE IN PHOTOSYNTHETIC METABOLISM

The activities of glycine oxidase (GO) and serine dehydratase (SD) wer e revealed in green leaves of wheat and maize. The enzymes were extrac ted by ammonium sulfate fractionation. GO localized in chloroplast and cytosolic fraction was most active at pH 8.0. Its activity was 1.5-2. 0 times higher in wheat than in maize and it declined with leaf aging. The enzyme converts glycine into glycollate and ammonium ion being fl avine dependent and generating H2O2. We propose that it is an L-amino- acid oxidase (EC 1.4.3.2) with a higher specificity to glycine. The ac tivity of SD (EC 4.2.1.13) localized in chloroplasts was maximum at pH 7.0-7.2, it was also higher in wheat than in maize. Pyruvate was dete rmined as a product of enzymatic conversion of L-serine. SD and GO act ivities were not revealed in etiolated leaves.