Purification of the fourth, second and fifth components of mouse complement.

The fourth, second and fifth components of mouse complement were purified by a combination of polyethylene glycol precipitation, ion exchange chromatography and gel filtration. The final products were homogeneous on SDS-PAGE, and the activity yields were 8.5% for C4, 32% for C2 and 40% for C5. C4 was composed of three polypeptide chains with mol. wts of 90,000, 78,000 and 32,000. C2 was composed of a single polypeptide chain with a mol. wt. of 115,000 and cleaved by C1s into two fragments with mol. wts of 80,000 and 35,000. The half life of C4b2a was 7 min and was not prolonged by the iodination of C2. C2 activity could not be measured using EAC14hu or EAC14gp cells, but measurement was possible with the use of EAC14mo cells with purified C5 components of mouse complement. C5 was composed of two polypeptide chains with mol. wts of 135,000 and 84,000. This is the first report on the purification of functionally active mouse complement components C4, C2 and C5 from plasma.