Purification of the first component of guinea-pig complement by gel chromatography

A method has been described for the purification of the first component (C1) of complement from guinea-pig serum. The procedure consists in euglobulin precipitation followed by gel filtration on agarose columns. The final product has low protein content and high specific activity. The protein obtained by this procedure has a molecular weight of about one million and has been further characterized using immunochemical and polyacrylamide gel electrophoresis techniques. The protein reacts with anti-C1 antiserum and forms the EAC1, 4-intermediate. The experiments indicated the existence of electrophoretic variants of C1. The dissociation of the C1 molecule by increasing the ionic strength is confirmed. The described procedure appears to be a useful method of obtaining functionally purified C1.