title: Creatine kinase B-subunit activity in serum after immunoinhibition of M-subunit activity.
abstract: Creatine kinase (EC 2.7.3.2) B-subunit activity in serum may be routinely measured as residual activity after specific immunoinhibition of the M-subunit. We assessed the inhibition kinetics, specificity, completeness of inhibition, and inhibitory capacity of three different anti-M preparations, with use of isolated human BB, MM, and MB isoenzymes. The Scandinavian-recommended reaction system was used. We suggest a set of tentative quality requirements for anti-M for use in diagnosing acute myocardial infarction. The need to measure and subtract sample residual adenylate kinase activity was demosntrated. We describe a routine photometric method for determining B-subunit activity in serum. With the Scandinavian CK method the upper reference value for total creatine kinase in serum was found to be 150 U/L for women, 270 U/L for men. By bioluminescence, we found the upper reference value for B-subunit activity to be 6 U/L for both sexes. We discuss three different modes for applying B-subunit determinations to the diagnosis of acute myocardial infarction.
mesh_terms: D000263:Adenylate Kinase / Q000097:blood; D000906:Antibodies; D000937:Antigen-Antibody Reactions; D003402:Creatine Kinase / Q000037:antagonists & inhibitors / Q000097:blood* / Q000276:immunology; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000097:blood* / Q000276:immunology; D007700:Kinetics; D009203:Myocardial Infarction / Q000201:enzymology; D010783:Photometry
chemical_list: D000906:Antibodies; D007527:Isoenzymes; D003402:Creatine Kinase; D000263:Adenylate Kinase