Purification and Characterization of a Novel Isozyme of Chitinase from Bombyx mori
75-kDa chitinase, which showed potential as a biocontrol agent against Japanese pine sawyer, was characterized after purification from the integument of the fifth instar larvae of <I>Bombyx mori</I> by chromatography on diethylaminoethyl (DEAE)-Toyoperal 650 (M), hydroxylapatite, and Fractogel EMD DEAE 650 (M) columns. The optimum pH was 6.0 toward <I>N</I>-acetylchitopentaose (GlcNAc<SUB>5</SUB>) and 10 toward glycolchitin. The optimum temperature was 60 °C toward GlcNAc<SUB>5</SUB> and 25 °C toward glycolchitn. The enzyme was stable at pH 7–10 and below 40 °C. Kinetic analysis and reaction-pattern analysis using glycolchitin and <I>N</I>-acetylchitooligosacchraides as substrates indicated that 75-kDa chitinase is an endo- or random-type hydrolytic enzyme to produce the β anomeric product and that it prefers the longer <I>N</I>-acetylchitooligosaccharides, suggesting, together with the <I>N</I>-terminal amino acid sequence, that the 75-kDa chitinase belongs to family 18 of glycosyl hydrolases.
- Bioscience, biotechnology, and biochemistry
Bioscience, biotechnology, and biochemistry 70(1), 252-262, 2006-01-23
Japan Society for Bioscience, Biotechnology, and Agrochemistry