Characterization of Hydrolysis and Transglycosylation by Testicular Hyaluronidase Using Ion-Spray Mass Spectrometry

Various oligosaccharides from hyaluronic acid, which were fluorescence-labeled and blocked by pyridylamination at the reducing terminal, were incubated as substrates or acceptors with bovine testicular hyaluronidase. Fluorescence-labeled reaction products in the reaction mixture were monitored selectively and directly by ion-spray mass spectrometry without chemical derivatization. As a result, several features of the relationship between oligosaccharides, substrates, and testicular hyaluronidase were clarified. When hexasaccharides or larger oligosaccharides having D-glucuronic acid at the nonreducing terminal were used as substrates, they were hydrolyzed sequentially to disaccharides from the nonreducing terminal, and these disaccharides were then transferred to other hexasaccharides. On the other hand, when heptasaccharides or larger oligosaccharides having N-acetyl-D-glucosamine at the nonreducing terminal were used as substrates, trisaccharides were released from the nonreducing terminal, and then also transferred to other hexasaccharides, thus forming nonasaccharides. Thus, the relationship between hydrolysis and transglycosylation reactions with testicular hyaluronidase was characterized using ion-spray mass spectrometry.