PRESENCE OF AN ENDO-BETA-GALACTOSIDASE DEGRADING THE LINKAGE REGION BETWEEN THE CHONDROITIN SULFATE CHAIN AND CORE PEPTIDE OF PROTEOGLYCAN

Pyridylamino chondroitin sulfate, of which the reducing terminal xylose was coupled with a fluorescent 2-aminopyridine, was incubated at pH 4.0 with an extract from the mid-gut gland of Patnopecten. The high- and low-molecular-weight products were separated by ethanol precipitation, and identified by high-performance liquid chromatography analysis. The enzyme was found to expose a galactose residue at the reducing terminus of chondroitin sulfate, and also released the pyridylamino disaccharide, galactosylxylose, from the reducing terminal site of pyridylamino chondroitin sulfate. These results suggest that endo-β-galactosidase activity, which hydrolyzes the galactosylgalactose linkage of peptidochondroitin sulfate, is present in the mid-gut gland of Patnopecten. © 1990.