title: Purification and characterization of a novel isozyme of chitinase from Bombyx mori.
abstract: 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 Bombyx mori by chromatography on diethylaminoethyl (DEAE)-Toyoperal 650 (M), hydroxylapatite, and Fractogel EMD DEAE 650 (M) columns. The optimum pH was 6.0 toward N-acetylchitopentaose (GlcNAc5) and 10 toward glycolchitin. The optimum temperature was 60 degrees C toward GlcNAc5 and 25 degrees C toward glycolchitn. The enzyme was stable at pH 7-10 and below 40 degrees C. Kinetic analysis and reaction-pattern analysis using glycolchitin and N-acetylchitooligosacchraides as substrates indicated that 75-kDa chitinase is an endo- or random-type hydrolytic enzyme to produce the beta anomeric product and that it prefers the longer N-acetylchitooligosaccharides, suggesting, together with the N-terminal amino acid sequence, that the 75-kDa chitinase belongs to family 18 of glycosyl hydrolases.
authors.affiliation: Department of Biological Science, Faculty of Agriculture, Yamaguchi University, Japan.
authors.forename: Khondkar Ehteshamul
authors.initials: KE
authors.lastname: Kabir
authors.forename: Daizo
authors.initials: D
authors.lastname: Hirowatari
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Watanabe
authors.forename: Daizo
authors.initials: D
authors.lastname: Koga
mesh_terms: D000107:Acetylation; D000595:Amino Acid Sequence; D000818:Animals; D012831:Bombyx / Q000201:enzymology*; D002686:Chitin / Q000737:chemistry / Q000378:metabolism; D002688:Chitinases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D007527:Isoenzymes; D002686:Chitin; D002688:Chitinases