Characterisation of the third component of canine and feline complement

Canine and feline C3 have been found by immune precipitation to have a molecular weight of 198K and 197K respectively. Each comprises two polypeptide chains α and β (canine α - 126K β - 72K; feline α - 125K β - 72K). The α chain is subsequently cleaved by C3b ina to produce two fragments α^edc (canine 65K; feline 64K) and α^fb (canine 40K; feline 46K). The findings are compared to the documented molecular structure of human C3.