Comparative study of free and membrane-bound acidic beta-D-glucosidase from the hepatopancreas of the shrimp Penaeus japonicus (Crustacea: decapoda).
l. In the hepatopancreas of the shrimp Penaeus japonicus the beta-glucosidase is present, either free or membrane-bound. The specific activity of the purified enzyme is 237,333 units/mg of protein and 191,111 units/mg of protein for the free and the membrane-bound beta-glucosidase, respectively. 2.The non-membrane-bound beta-glucosidase appears to be the same molecular size as the membrane-bound enzyme, both being monomers and consisting of a polypeptide chain of apparent M(r) 65,000, as estimated by chromatography on Superose 12 and by SDS-PAGE. 3.Both enzymes share similarities in their molecular size and substrate specificities (with ratios of 100:17:4:12 for the non-membrane-bound and 100:32:13:12 for the membrane-bound enzyme for the activities with methylumbelliferyl-beta-D-glucoside, methylumbelliferyl-beta-D-galactoside, methylumbelliferyl-alpha -L-arabinopyranoside and methylumbelliferyl-beta-xyloside respectively, as substrates). 4.The membrane-bound beta-glucosidase can be differentiated from the non-membrane-bound enzyme by its isoelectric point (7.5 vs 6.6), Km (182 micrometer vs 76 micrometer), pH optimum (4.5 vs 5.5), phosphorylation,sialyation and thermostability.
Chuang
N N
NN
Division of Biochemistry and Molecular Science, Institute of Zoology, Academia Sinica, Nankang, Taipei,Republic of China.
Huang
J D
JD
Lin
K S
KS
D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D043143:Hepatopancreas / Q000201:enzymology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D008565:Membrane Proteins / Q000378:metabolism*; D008970:Molecular Weight; D033561:Penaeidae / Q000201:enzymology*; D010766:Phosphorylation; D013379:Substrate Specificity; D013997:Time Factors; D001617:beta-Glucosidase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
D008565:Membrane Proteins; D001617:beta-Glucosidase