The purification and characterization of bovine C4, the fourth component of complement

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Abstract
C4 was isolated from bovine plasma in high yield by using simple purification techniques. The protein, like human C4, is a .beta.-globulin with a MW of about 200,000 and consists of 3 polypeptide chains, .alpha., .beta. and .gamma., with apparent MW of 98,000, 82,000 and 32,000, respectively. The chains of C4 were separated by methods previously used for human C4. Their amino acid compositions are very similar to those of the human component, but differences in carbohydrate distribution were observed. The hemolytic activity of bovine C4 is totally destroyed by incubation with bovine .**GRAPHIC**. the activated subcomponent of C4, treated in this way, was cleaved in the .alpha. chain, which was decreased in MW by about 9000, corresponding to the removal of C4a.