Characterization of 38 kDa and 42 kDa chitinase isozymes from the liver of
Japanese common squid Todarodes pacificus |
| |
Authors: | Masahiro MATSUMIYA Kouji MIYAUCHI AND Atsushi MOCHIZUKI |
| |
Institution: | Department of Marine Science and Resources, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa 252-8510, Japan |
| |
Abstract: | ABSTRACT: Characterization was investigated on the 38 kDa and 42 kDa chitinase (EC3.2.1.14) isozymes from the liver of Japanese common squid Todarodes pacificus . Optimum pH toward colloidal chitin was observed at pH 3.0 for the 38 kDa chitinase, and pH 3.0 and 9.0 for the 42 kDa chitinase. K m and k cat of the 38 kDa and 42 kDa chitinases toward a longer substrate, glycol chitin, were 0.071 mg/mL and 1.22/s, and 0.074 mg/mL and 0.196/s, respectively. Alternatively, strong substrate inhibition of both chitinases were observed toward a short substrate, N -acetylchitopentaose (GlcNAc5). Both chitinases decomposed not only chitin but also chitosan (D. A. 95%). The cleavage pattern and reaction rate were investigated using N -acetylchitooligosaccharides (GlcNAcn, n = 2–6). Both chitinases hydrolyzed GlcNAcn ( n = 4,5, and 6). The release of GlcNAc was not observed. The speed of the reaction was observed to be in the following order: GlcNAc4 > GlcNAc5 > GlcNAc6 for the 38 kDa chitinase, and GlcNAc6 > GlcNAc5 > GlcNAc4 for the 42 kDa chitinase. Both the chitinases released p -nitrophenol from p -nitrophenyl GlcNAcn ( n = 2, 3, and 4). N-terminal amino acid sequences of the 38 kDa and 42 kDa chitinases were YLLSXYFTNWSQYRPGAGKYFPQNI and EYRKVXYYTNWSQYREVPAKFFPEN, respectively. |
| |
Keywords: | amino acid sequence characterization chitinase Japanese common squid kinetics liver substrate specificity Todarodes pacificus |
|
|