Amino acid sequence of a peptide from keratan sulfate II-core protein linkage regions

Keratan sulfate II was prepared from the proteolytic digest of pig nucleus pulposus proteoglycan. The polysaccharide chains containing the fragment peptides of the core protein at their reducing terminal were subjected to anhydrous HF-solvolysis reaction and one of the glycopeptides from the keratan sulfate II-core protein linkage regions was isolated. The amino acid sequence of the peptide was deduced to be Ala-Pro-Ser-Pro-Gly, which is different from those reported for the attachment sites of chondroitin sulfate on core proteins from various sources. The results provided the first solid amino acid sequence for the keratan sulfate II-core protein linkage regions and suggested that the amino acid sequence of the core protein might determine the distribution of chondroitin sulfates and keratan sulfates along the core protein of the proteoglycan molecule.