Purification, Crystallization, and Characterization of a Novel Protopectinase fromBacillus subtilis

Abstract

We found a novel protopectinase that did not catalyze the degradation of polygalacturonic acid in the culture filtrate of Bacillus subtilis IFO 12113. The enzyme was purified by CM-Sephadex C-50 column chromatography, heat treatment at 60°C, and column chromatography on DEAE-Toyopearl 650M and Toyopearl HW-55S. The enzyme was isolated as a homogeneous protein, and was finally isolated as crystals. The molecular weight of the enzyme was estimated to be 30,000 by gel permeation chromatography and by SDS-polyacrylamide gel electrophoresis, and 29,800 by sedimentation analysis. Its isoelectric point was around pH 9.4. The enzyme was thermostable; its activity was not lessened by being heated at 60°C for lOmin. The enzyme catalyzed the degradation of arabinogalactan from soybean seeds. Some strains belonging to the genus Bacillus, such as B. amyloliquefaciens, B. cere us, B. circulans, B. coagulans, B. firmus, B. licheniformis, B. macerans, and B. pumilus, produced the same kind of protopectinase.