Glycosidase activity in the post-ecdysial cuticle of the blue crab, Callinectes sapidus.

R D Roer, K E Halbrook, T H Shafer

Index: Comp. Biochem. Physiol. B Biochem. Mol. Biol. 128(4) , 683-90, (2001)

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Abstract

We have previously demonstrated a marked change in sugar moieties of glycoproteins of the cuticle of the blue crab, Callinectes sapidus, between 0.5 and 3 h post-ecdysis. The present study has identified a glycosidase that appears in the cuticle during the early post-ecdysial hours. The enzyme has affinities for p-nitrophenyl derivatives of both N-acetylglucosamine and N-acetylgalactosamine. Both activities are competitively inhibited by chitobiose, suggesting that the enzyme could be a N-acetylhexosaminidase (EC 3.2.1.52). Atypical of N-acetylhexosaminidases described to date, this enzyme has a pH optimum of 7.0. The enzyme activity is high during the post-ecdysial period coincident with the changes in glycoprotein profiles observed in vivo. Partial purification of the enzyme has been accomplished by Sephacryl size-exclusion chromatography followed by concanavalin A affinity chromatography.