Occurrence of keratan sulfate in connective tissues of teleost [Pacific mackerel, Scomber japonicus]

A new method for the detection of keratan sulfate in connective tissue has been developed without its prior isolation from a mixture of glycosaminoglycan. The method relies on the specificaction of an endo-β-galactosidase from Flavobacterium sp. on keratan sulfate. Besides being found in mammals, keratan sulfate is widely distributed in the connective tissues of teleost; it is especially abundant in the skin, cornea, and caudal fin of Pacific mackerel, and in the cornea of horse mackerel. From the skin of Pacific mackerel, a crude preparation of polysaccharide was obtained, which contained a large amount of carbohydrate chains susceptible to endo-β-galactosidase. The fraction with the carbohydrate chains was isolated by treating the preparation with hyaluronidase and chondroitinase ABC. The purified substance was characterized using chemical and infrared spectrum analyses, and was indentified as keratan sulfate. This paper is the first report to demonstrate the presence of keratan sulfate in skin tissue.