title: Kinetics of activation of the first component of complement (C1) by IgG oligomers.
abstract: 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.
mesh_terms: 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
chemical_list: 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