Subcomponents C1q of the first component of guinea pig and mouse complement: Comparative study of their asparagine-linked sugar chains

Guinea pig and mouse C1q, subcomponents of the first component of complement, contained six asparagine-linked sugar chains on the C-terminal non-collagenous globular regions of each molecule. After N-acetylation and successive NaB³H₄-reduction of asparagine-linked sugar chains liberated by hydrazinolysis, their structure was analysed by sequential exoglycosidase digestion in combination with sugar composition analyses. The sugar chains of C1q molecules of both animals were very similar and composed of the biantennary complex type sugar chains with the following outer chains in various combinations: (± NeuNAcα → )Galß1 → GlcNAcß1 → and Galß1 → Galß1 → GlcNAcß1 →. These chain moieties were found to be linked to a common core structure of Manα1 → (Manα1 → )Manß1 → GlcNAcß1 → (Fucα1 → )GlcNAc.