Characterization of a β-D-mannosidase from a marine gastropod, Aplysia kurodai.

摘要: Abstract A β-D-mannosidase (EC 3.2.1.25) with a molecular mass of approximately 100 kDa was purified from the digestive fluid marine gastropod Aplysia kurodai by ammonium sulfate fractionation followed column chromatographies on TOYOPEARL Butyl-650 M, DEAE-650 M, and Superdex 200 10/300 GL. This enzyme, named AkMnsd in present study, showed optimal activities at pH 4.5 40 °C stable acidic range 2.0 to 6.7 temperature below 38 °C. The Km Vmax values for determined 6.0 30 °C p-nitrophenyl β- d -mannopyranoside were 0.10 mM 3.75 μmol/min/mg, respectively. degraded various polymer mannans as well mannooligosaccharides liberating mannose major degradation product. Linear mannan green alga Codium fragile completely depolymerized presence AkMan, an endolytic β-mannanase, which we previously isolated same animal (Zahura et al., Comp. Biochem. Physiol. B 157, 137–148 (2010)). cDNA encoding amplified hepatopancreas PCR using degenerated primers designed basis N-terminal internal amino-acid sequences AkMnsd. cloned consisted 2985 bp encoded sequence 931 residues calculated 101,970 Da. deduced 20–43% identity those glycoside-hydrolase-family 2 (GHF2) β-mannosidases. catalytically important GHF2 enzymes conserved Thus, is regarded new member mannosidase gastropod.