Expression of the Chitinase III Gene ofAeromonassp. No. 10S-24 inEscherichia coli

Abstract

The chitinase III gene of Aeromonas sp. No. 10S-24 was expressed in Escherichia coli. Production of chitinase III by E. coli was 3-fold higher than that of chitinases in the culture supernatant of Aeromonas sp. The enzyme from E. coli was purified and characterized. The molecular weight of the chitinase III from E. coli was estimated by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) to be 55,000. This agreed with the calculated molecular weight of the mature chitinase III (54,111). However, it was different from that of the enzyme from Aeromonas sp. It showed that the chitinase III from Aeromonas sp. had an additional sugar chain, causing the higher molecular weight. Chitinase III from E. coli had almost the same enzymatic properties as chitinase III from Aeromonas sp., but the specific activity of the chitinase III from E. coli is slightly higher than that of the native chitinase III. Both enzymes hydrolyzed chitosan (80% deacetylated) well.