Isolation and characterisation of a small dermatan sulphate proteoglycan from ray skin (Raja clavata)

The major proteoglycan of ray (Raja clavata) skin, which is a dermatan sulp hate proteoglycan, DSI-PG, was extracted, isolated and characterised. This proteoglycan has an average molecular size (M-r) of 110 kDa, and is compose d of one dermatan sulphate chain (M-r 55 kDa) and uronic acid containing ol igosaccharides attached to the protein core. SDS-polyacrylamide gel electro phoresis of chondroitinase ABC deglycosylated PG revealed three protein cor es with M(r)s of about 57, 43 and 31 kDa. The amino acid composition of thi s preparation showed large amounts of phenylalanine, glutamic acid/glutamin e, glycine, threonine and serine; cysteine was not detected. Dermatan sulph ate is rich in iduronic acid (68% of total uronic acid) and composed mainly of mono-sulphated disaccharides bearing esterified sulphate groups at posi tions C-4 (61%) or C-6 (4%), disulphated disaccharides with a peculiar sulp hation pattern (32%) and a minor portion of non-sulphated ones (3%). The fi ndings indicate that the major proteoglycan of ray skin is a small dermatan sulphate proteoglycan and suggest that the dermatan sulphate chain contain s some sulphated disaccharide units with esterified sulphate groups possibl y at the C-2 and/or C-3 position(s) of the uronic acid. (C) 1999 Elsevier S cience Inc. All rights reserved.