Purification and characterization of acidic alpha-D-mannosidase from the hepatopancreas of the shrimp Penaeus monodon (Crustacea: Decapoda).

ABSTRACT

Acidic alpha-D-mannosidase purified from the hepatopancreas of Penaeus monodon is pentameric, with a Mr 251,000 as estimated by size-exclusion FPLC on a Superose 12, and retains a hydrophobic domain, being stable to heating at 65 degree C for 1 h. The specific activity of the purified enzyme is 1,923 units/mg of protein. After polyacrylamide gel electrophoresis under denaturing conditions, the purified acidic alpha-D-mannosidase from shrimp was found to consist of a single homogeneous type of monomer of Mr 51,000. The purified enzyme has an isoelectric point of 4.4 +/- 0.1 and becomes more alkaline after the removal of either sialic acid or phosphate groups. The apparent K(m), value of alpha-D-mannosidase from shrimp hepatopancreas with 4-methylumbelliferyl-alpha-D-mannopyranoside as substrate is 243 micrometer.