Kinetics of activation of the first component of complement (C1) by IgG oligomers.
The rate of activation of the first component of complement, Cl, by IgG oligomers was investigated. The kinetics of Clr activation exhibited a pronounced lag phase at low IgG concentration and were followed by a rapid conversion of the proenzyme Cls to Cls. Activation of Cl resulted in a conformational change of this complex. Bases on these results, a model of Cl activation by IgG oligomers is proposed: The efficiency of Cl activation by IgG oligomers is in parallel to their binding affinity to Clq. Clr undergoes a slow rearrangement to a conformation which is not stable and is autoactivated, then Clr rapidly converts Cls to Cls.
D000936:Antigen-Antibody Complex / Q000378:metabolism; D002942:Circular Dichroism; D003166:Complement Activating Enzymes / Q000378:metabolism; D003167:Complement Activation; D003172:Complement C1 / Q000378:metabolism*; D015922:Complement C1q; D015923:Complement C1r; D003173:Complement C1s; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism*; D007700:Kinetics; D046911:Macromolecular Substances; D008954:Models, Biological; D013997:Time Factors
D000936:Antigen-Antibody Complex; D003172:Complement C1; D007074:Immunoglobulin G; D046911:Macromolecular Substances; D015922:Complement C1q; D003166:Complement Activating Enzymes; D015923:Complement C1r; D003173:Complement C1s