The asparagine-linked sugar chains of subcomponent C1q of the first component of human complement

Abstract

Human C1q, a subcomponent of the first component of complement, contains six asparagine-linked sugar chains in 1 molecule. The sugar chains are exclusively located in the COOH-terminal globular region which is composed of 330 amino acid residues. The sugar chains were liberated from the polypeptide portion by hydrazinolysis, and their structures were studied by the combination of sequential exoglycosidase digestion and methylation analysis. Based on the results, the structures NeuAcalpha2 leads to 6Galbeta1 leads to 4GlcNAcbeta1 leads to 2Manalpha1 leads to 6(+/- NeuAcalpha2 leads to 6Galbeta1 leads to 4GlcNAcbeta1 leads to 2Manalpha1 leads to 3)Manbeta1 leads to 4GlcNAcbeta1 leads to 4(+/-Fucalpha1 leads to 6)GlcNAc were confirmed.