The NH2-terminal amino acid sequence of bovine skin proteodermatan sulfate

Deglycosylation of bovine skin proteodermatan sulfate with chondroitinase ABC yielded a protein core with an apparent molecular weight of about 45,000. The amino acid sequence of this preparation was determined up to position 24. This region was enriched in acidic amino acids and proline compared with the whole protein core and it was predicted to be highly folded. The amino acid sequence determined in these experiments has a gap at position 4. Results obtained after beta-elimination-sulfite addition showed that residue 4 was an O-substituted hydroxyamino acid. The latter was identified as serine by sequencing the NH2-terminal region of the protein core (Mr approximately 43,000) isolated after a more complete deglycosylation of the proteoglycan with anhydrous HF. Serine 4 may be an attachment site for one of the few dermatan sulfate chains present in the proteoglycan.