Comparison of Characteristics of β-N-Acetylhexosaminidase from Moon Jellyfish Aurelia aurita with Those from Other Species

抄録

β-N-Acetylhexosaminidase (EC 3. 2. 1. 52) in moon jellyfish mesogloea was extracted with 50mM sodium phosphate buffer (pH 6.0) and purified by chromatographies on CM-Toyopearl 650M and Toyopearl HW-55 F. By these two purification steps, the enzyme was isolated from crude extracts. A final specific activity of 17875 units/mg and 19-fold purification were attained. The molecular weight of the enzyme was estimated to be about 130, 000 by gel filtration on Toyopearl HW-55F. By SDS-PAGE, the enzyme was composed of a subunit molecular mass of 64, 000. The optimum pH was 4 and the enzyme was stable at the range between 4 and 5. This enzyme was extremely unstable in comparison with those from other species. The optimum temperature was 50°C. The enzyme was strongly inhibited by Hg²⁺, CH₂ICOOH, and DTNB, but was slightly activated by K⁺, Na⁺, Mg²⁺, Cu²⁺, and Ca²⁺. The enzyme hydrolyzed various oligosaccharides, and the rate of hydrolysis of N-acetylchitooligosaccharides tended to decrease with increasing degree of polymerization of the substrate. Moreover, in comparison with some other species, this enzyme had a high affinity for p-nitrophenyl-2-acetamide-2-deoxy-β-D-glucopyranoside.