evidence of tryptophan at or near active site of glucoamylase i of arthrobotrys amerospora

arthrobotrysamerospora (atcc 34468) produced glucoamylase in a semi-synthetic medium containing starch as a sole carbon source. polyacrylamide gel electrophoresis of crude glucoamylase showed three isoenzymes. they were designated as glu i, glu ii and glu iii according to their electrophoretic mobility. these iso-glucoamylases were purified by column chromatography using deae-sephadex a-50. the major fraction, namely glu i, was subjected to various group specific reagents like nem, idoacetamide, palp, dep, rose bengal, nbs and acarbose. n-bromosuccinimide and acarbose totally inhibited glu i. hg2+ ion did not inhibit glu i activity at 25 m mol concentration. glu i also showed raw starch activity.