PURIFICATION AND CHARACTERIZATION OF AN ENDO-POLYGALACTURONASE FROM THE GUT OF WEST-INDIES SUGARCANE ROOTSTALK BORER WEEVIL (DIAPREPES-ABBREVIATUS L.) LARVAE

An endo-polygalacturonase (PG) (EC:3.2.1.15) with a pi of 9.4 and an M -r of 44,500 was purified to electrophoretic homogeneity from the gut of West Indies sugarcane rootstalk borer weevil (Diaprepes abbreviatus L.) larvae. Hydrolytic activity was maximal in 150 mM sodium acetate, pH 5.5, at 30 degrees C. Kinetic determinations yielded an apparent K -m of 3.68 mg polygalacturonic acid (PGA)/ml and a V-max of 283 mu mol galacturonic acid/min/mg protein for PGA. Enzymatic activity was inhi bited by a polygalacturonase inhibitor protein from ''Hamlin'' orange flavedo. The purified protein does nor. appear to be glycosylated, and its N-terminal sequence showed no homology to any PG protein sequence s in data banks. (C) 1997 Elsevier Science Inc.