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. II. Physico-chemical characterization of the activated complex.
abstract: A complex, CVF-B, between cobra venom factor (CVF) and human factor B(B) showed weak, short-lived enzymatic activity against the third component of human complement (C3). Once activated with trypsin, it showed strong, stable activity against C3 and C5. CVF-B, an activated form of CVF-B complex, was not affected by the trypsin inhibitor, diisopropylfluorophosphate and neuraminidase. Heating at 56 C for 30 min completely destroyed its activity and heating at 50 C for 30 min destroyed approximately half its activity. The activity of DVF-B decrease markedly at pH 6.0 but was stable at pH 6.5 to 8.5. CVF-B lost 90% of its activity on reduction with 1 mM dithiothreitol, and was completely adsorbed on a cellulose acetate membrane. CVF-B was found to be a complex of CVF and glycine-rich gamma-glycoprotein, with a molecular weight of 340,000. The CVF-B molecule consisted of 4-polypeptide chains, 3 of which were derived from CVF and one from GGG. Hemolytically active CVF-B may be formed from 2 molecules with four-polypeptide chains linked by unknown bonds. Human, rat and guinea pig sera could react with CVF-B to generate a lytic factor. Human and sheep erythrocytes were not sensitive to the lytic factor generated by CVF-B, whereas liposomes prepared from their membrane lipids were equally sensitive to the lytic factor.
mesh_terms: D000017:ABO Blood-Group System; D000818:Animals; D003176:Complement C3; D003182:Complement C5; D003165:Complement System Proteins; D004789:Enzyme Activation; D004912:Erythrocytes; D006168:Guinea Pigs; D006461:Hemolysis; D006358:Hot Temperature; D006801:Humans; D007531:Isoflurophate; D008081:Liposomes; D051379:Mice; D008970:Molecular Weight; D009439:Neuraminidase; D011817:Rabbits; D051381:Rats; D012756:Sheep; D012910:Snake Venoms; D014357:Trypsin; D014361:Trypsin Inhibitors
chemical_list: D000017:ABO Blood-Group System; D003176:Complement C3; D003182:Complement C5; D008081:Liposomes; D012910:Snake Venoms; D014361:Trypsin Inhibitors; D007531:Isoflurophate; D003165:Complement System Proteins; D009439:Neuraminidase; D014357:Trypsin