title: Trypsin-activated complex of human factor B with cobra venom factor (CVF), cleaving C3 and C5 and generating a lytic factor for unsensitized guinea pig erythrocytes. I. Generation of the activated complex.
abstract: A complex formed between cobra venom factor (CVF) and isolated human factor B (B) was found to be converted by trypsin to a stable enzyme, CVF-B which cleaved the third component (C3) and the fifth component (C5) of human complement. The formation of CVF-B by trypsin required divalent cations, whereas the formation of the lytic factor from human serum occurred even in the presence of EDTA. CVF-B purified by gel filtration could initiate the hemolysis of unsensitized guinea pig erythrocytes when incubated with human complement components C5 to C9 in 0.01 M EDTA buffer. C3 was not required for the lysis of guinea pig erythrocytes initiated by CVF-B because of the beta1C precipitation line formed between human serum and anti-beta1C antibody did not inhibit the hemolysis by CVF-B in agarose gel. Treatment of beta1C and beta1F globulins in whole human serum with CVF-B in the presence of 0.01 M EDTA converted them to components with higher mobilities on immunoelectrophoresis.
mesh_terms: D000017:ABO Blood-Group System; D000818:Animals; D003176:Complement C3; D003182:Complement C5; D003183:Complement C6; D003184:Complement C7; D003185:Complement C8; D003186:Complement C9; D003165:Complement System Proteins; D004789:Enzyme Activation; D004912:Erythrocytes; D006168:Guinea Pigs; D006461:Hemolysis; D006801:Humans; D012910:Snake Venoms; D014357:Trypsin
chemical_list: D000017:ABO Blood-Group System; D003176:Complement C3; D003182:Complement C5; D003183:Complement C6; D003184:Complement C7; D003185:Complement C8; D003186:Complement C9; D012910:Snake Venoms; D003165:Complement System Proteins; D014357:Trypsin