ISOLATION AND STUDY OF MURINE C3

Abstract

C3 [complement component 3] was isolated in purified form from fresh murine serum and plasma by precipitation as euglobulin followed by removal of other proteins on immunoadsorbent columns bearing antibodies raised against specifically C3-depleted serum. Recovery was 30-55% and the C3 was all in its native form. Functional activity was demonstrated by fixation of the C3 on .**GRAPHIC**. cells and by interaction with lymphocyte C3 receptors. Mouse C3 in plasma and after isolation had a MW of 240,000. Its cleavage by classical pathway and cobra factor induced C3 convertases and by trypsin yielded a major conversion product with a MW not less than 210,000, the electrophoretic mobility of which differed when it was generated from isolated C3 rather than in plasma.