Chondroitin sulfate-specific novel hydrolase in human

Abstract

Chondroitin sulfate (CS) is widely distributed as the glycosaminoglycan side chains of proteoglycans in extracellular matrices and at the cell surface. CS chains have a linear structure composed of repeating disaccharide units comprising d-glucuronic acid and N-acetyl-d-galactosamine, which are sulfated at different positions in various combinations. This structural diversity is responsible for the multiple biological functions of CS. The cellular degradation of CS occurs predominantly in lysosomes. Following the fragmentation of polysaccharides by endo-type hydrolases, the oligosaccharide products are degraded sequentially from the nonreducing end by exo-type glycosidases and sulfatases, although no endoglycosidases specific to CS have been reported. In this study, human hyaluronidase-4 was demonstrated to be a CS-specific endo-beta-N-acetylgalactosaminidase. The specificity of a purified recombinant form of the enzyme was investigated using various CS isoforms, and the structure of the best cleavage site was characterized. This enzyme will be a useful tool for investigating CS-specific functions in tissues and cells without degrading hyaluronan. It may also be applicable to the treatment of acute spinal cord injuries instead of the bacterial CS lyase used in recent clinical trials. © 2012 Springer Science+Business Media, LLC.