title: Interaction between human IgG and human creatine kinase isoenzyme-1 in serum: a route for the intravascular catabolism of creatine kinase-1?
abstract: In vitro incubation, at 37 degrees C, of human creatine kinase isoenzyme-1 (isoenzyme BB) and human immunoglobulin G in a buffer results in the formation of a complex of high relative molecular mass (Mr approximately 825,000), which contains both proteins. This complex also forms in vitro if creatine kinase isoenzyme-1 is incubated with fresh human serum. The creatine kinase activity of the complex obtained from either incubation is extremely labile, even in the presence of a chelating agent and a thioglycerol. We present evidence for the existence of this complex in the sera of patients who have detectable serum creatine kinase isoenzyme-1 activity. Sera with high activities of creatine kinase isoenzyme-2 do not appear to have this complex. We therefore speculate that complexing of creatine kinase isoenzyme-1 with serum immunoglobulin G may be a pathway of enzyme degradation.
mesh_terms: D003402:Creatine Kinase / Q000097:blood; D006801:Humans; D007122:Immunoelectrophoresis; D007074:Immunoglobulin G; D007527:Isoenzymes / Q000097:blood; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D011485:Protein Binding
chemical_list: D007074:Immunoglobulin G; D007527:Isoenzymes; D046911:Macromolecular Substances; D003402:Creatine Kinase