Complement C3b, Human

Native, human C3b complement component. Cleavage of the C3-α chain at peptide bond 77 by either of the complement C3 convertase enzymes results in production of C3a (M.W. 9083) and C3b (M.W. 180,000) fragments. The C3b fragment is a glycoprotein composed of the modified C3-α chain (α′) (M.W. 105,000) and the intact C3-β chain (M.W. 75,000). Nascent C3b has the transient ability to form a covalent ester bond with a variety of target surfaces. Once bound to target surfaces C3b becomes an essential subunit of both the classical and alternative pathway C5 cleaving enzymes. In addition, surface-bound C3b has opsonic and immune adherence activities which are mediated via binding to CR1 (CD35) complement receptors.

In PBS, pH 7.2, filtered through a 0.22 µm filter.

Following initial thaw, aliquot and freeze (-70°C).

Prepared from serum that has been shown by certified tests to be negative for HBsAg and for antibodies to HIV and HCV.

Wong, W.W. and Fearon, D.T. 1987. Methods Enzymol.150, 579.
Arnout, M.A., et al. 1981. J. Immunol.127, 1348.

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Toxicity: Standard Handling (A)