MULTIPLE FORMS OF ACID-PHOSPHATASE IN GERMINATING-SEEDS OF VIGNA-SINENSIS

Acid phosphatase activity increases during germination of Vigna sinenesis. Four forms of acid phosphatase (AP-I, AP-II, AP-III and AP-IV) have been detected in preparations of 96 hr germinating seeds by zymogram analysis. These phosphatases were partially purified by ammonium sulphate precipitation, ion exchange chromatography and gel filtration. The M(r)s of AP-I, AP-II, AP-III and AP-IV were determined by gel filtration to be 150 000, 98 000, 48 000 and 62 000, respectively. Their temperature and pH optima are approximately 60-degrees and approximately 5.0, respectively. The activities of the phosphatases were inhibited by Fe3+, Hg2+, Mo6+, Zn2+ and were activated by Triton X-100. Nucleoside phosphates were more preferentially hydrolysed than the sugar phosphates. NaF and PCMB are non-competitive inhibitors of these enzymes whereas phosphate inhibited them competitively. In addition to phosphatase activity, the AP-I enzyme fraction also has pyrophosphatase activity. The phosphatase and pyrophosphatase activities in AP-I were further characterized. The results presented in this paper suggest that the phosphatase and pyrophosphatase activities in AP-I reside either in a single protein or in two different yet very similar proteins.