GLYCOSIDASES OF TURNIP LEAF TISSUES .2. ISOLATION, PURIFICATION, AND SOME PHYSIOCHEMICAL CHARACTERIZATION

A number of glycosidase enzymes have been isolated and identified in h ealthy fresh leaves of turnip. Myrosinase (beta-thioglucosidase, EC. 3 .2.3.1), disaccharase (beta-fructofuranosidase, EC. 3.2.1.26), and bet a-amylase (alpha-1,4-glucan maltohydrolase, EC 3.2.1.2) have been isol ated and purified in powder form. The purification methods were saltin g out with ammonium sulfate, DEAE-cellulose column chromatography, hyd roxylapatite batch chromatography, and gel filtration through Sephadex G-200. Four isoenzymes of myrosinase enzyme could be isolated. The mo st active one was purified (131.3 times) and found to have an SA of 19 .7 U/mg. An enzyme causing hydrolysis of amylose and glycogen has been isolated and partially purified. It had an SA of 22.6 U/mg and 49.1-f old purification. Seven isoenzymes of disaccharase were isolated, but only one was purified (C) with SA of 1448.5 U/mg and 1316.8-fold purif ication. The yield of the purified myrosinase and disaccharase enzymes was 3.68 and 0.5 mg, respectively, from 100 gm dry wt of turnip leave s. Confirmation of purity with disk electrophoresis was performed. A s ingle sharp band was obtained for each pure enzyme by disk electrophor esis. The chromatographic analysis of the hydrolytic end product of th e beta-amylase indicated the presence of maltose. This results confirm the beta-form of amylase enzyme.