Isolation of the third component of complement and its derivative with anaphylatoxin-like activity from the plasma of the newt Cynops pyrrhogaster

Abstract The third component of complement (C3) of a newt, Cynops pyrrhogaster , was purified using a fast protein liquid chromatography technique. The purified newt C3 consists of two polypeptide chains (the molecular masses of the α and β-chains of C3 were 120,000 and 70,000, respectively) linked by disulfide bonds. The α-chain retained an internal thiolester bond that was cleaved with methylamine, and the N-terminal amino acid sequence of the α-chain was XVQLIDAKAGKAAKF. Digestion of newt C3 with trypsin yielded fragments that induced significant histamine release from newt peritoneal cells. These results indicate that newt C3 retains structural and functional properties shared with mammalian C3.