Functional Expression and Characterization of Recombinant Chitinase from Antarctic Psychrophilic Bacterium Sanguibacter antarcticus KCTC 13143

Abstract

A psychrophilic Sanguibacter antarcticus KCTC 13143 has been previously isolated from sea sand on King Sejong Station in Antarctica. An cold-active endochitinase gene, designated chi21702, from KCTC 13143 was PCR-amplified, cloned into pEXP5-CT/TOPO vector, and overexpressed in Eschrichia coli BL21(DE3) without its signal-peptide and with an C-terminal His-tag. The recombinant chitinase (R-Chi21702) was approximately 56 kDa in size, most of which was converted to inclusion body having no chitinae activity against oligomers of N-acetylglucosamine. In next step, refolding experiment for the inert chitinase was carried out using optimized refolding conditions. The refolded R-Chi21702 was then purified using a Ni-NTA column, which restored its chitinase specific activity (5.0 U/mg). The optimal reaction temperature and pH of R-chitinase were determined to be 40 ℃ and pH 8.0, respectively.