Amino acid sequence analysis of the glycopeptides from human complement component C3

摘要

>Human complement component C3 has been cleaved completely by trypsin in the presence of 2-propanol. The hydrolysate was fully solubilized and fractionated by reversed-phase HPLC. Two peptides only contained glucosamine, Unambiguous sequence analyses identified Asn-63 of the β-chain and Asn-268 of the α-chain as the sites of carbohydrate attachment. A third potential Asn-Xaa-Thr/Ser glycosylation site, Asn-946 of the α-chain, is not modified. The different states of glycosylation of the three sites cannot be explained by differences in exposure or secondary structure. All three are predicted reverse turn.