Purification and characterization of the chitinase (ChiA) from Enterobacter sp. G-1

Enterobacter sp, G-1 which produces chitinolytic and chitosanolytic enzymes, was previously isolated in our laboratory, One major chitinase, designated ChiA, was purified 42.9-fold from a culture filtrate of Enterobacter sp, G-1. To purify the chitinase, ammonium sulfate fractionation, DEAE-Sephadex A-50 column chromatography, and gel filtration on Sephadex G-100 column chromatography were used, The ChiA protein had a molecular weight of 60,000 estimated by SDS polyacrylamide gel electrophoresis and an isoelectric point of 6.6, The optimal pH and optimal temperature of ChiA against colloidal chitin were pH 7.0, and 40 degrees C, respectively. The purified ChiA degraded colloidal chitin mainly to GlcNAc(2) with a small amount of GlcNAc(3) and GlcNAc(4). ChiA hydrolyzed flaked chitin, colloidal chitin, and ethylenglycol chitin, but did not hydrolyze carboxymethyl cellulose (CMC), nor >90% deacetylated flaked chitosan, The chitinase activity was 42% inhibited by 10 mM EDTA, but was not inhibited by Ca2+ (<50 mM) or NaCl (<400 mM). The purified ChiA hydrolyzed colloidal chitin and chitin-related compounds in an endo splitting manner.