Purification of the human complement protein C1q by affinity chromatography.

Abstract

A subunit of the first component of human complement C1q, was purified by the technique of affinity chromatography. The chromatographic resin was cyanogen bromide-activated Sepharose covalently linked to human IgG. For the removal of traces of IgM it was necessary to subject further the C1q obtained from the chromatographic step to ultracentrifugation in sucrose gradients. The highly purified C1q was characterized immunochemically and according to its electrophoretic mobility in polyacrylamide gel. The purified material was capable of combining with C1r and C1s to reconstitute fully active macromolecular C1.