Transglycosylation reactions performed by glycosyl hydrolases from the marine anaspidean mollusc Aplysia fasciata

The search for glycosyl hydrolytic activities from natural sources and the investigation of their transglycosylation potential can provide enzymes with new interesting catalytic activities for the synthesis of oligosaccharides. We focused our attention on the sea hare Aplysia fasciata Poiret, 1789, a common Mediterranean opistobranch mollusc, describing the results on the presence of different glycosyl hydrolases found in this organism. The activities of interest are present in the visceral mass and in the hepatopancreas extracts which were highly active with respect to those from other marine molluscs, namely an exo--d-glucosidase activity and a -galactosidase, were investigated. The former is able to produce panose in high percentage by transglycosylation from maltose, or -d-glucosides of -methyl mannopyranoside and 2-deoxyglucose using p-nitrophenyl-d-glucopyranoside as donor. The -galactosidase from hepatopancreas produced in transgalactosylation reactions the -Gal-(1-4)-GlcNAc as the most abundant product and Gal-Xyl disaccharides of biological importance using p-nitrophenyl -d-galactopyranoside as donor and GlcNAc or benzyl -xyloside as acceptors, respectively.