ADENYLATE KINASE MIMICS CREATINE KINASE-MM ISOENZYME IN A CK ISOENZYME ELECTROPHORESIS ASSAY

Adenylate kinase activity (AK) originating from erythrocytes, present in hemolyzed serum behaves like creatine kinase MM isoenzyme (CK-MM) i n some CK electrophoresis assays that employ, in their visualization r eagent kits, adenosine monophosphate (AMP) as the sole inhibitor of AK , rather than a combination of AMP and a more potent inhibitor of eryt hrocyte AK, diadenosine pentaphosphate (Ap5A), to inhibit all contamin ating-AK activities in serum and quantify only the CK isoenzyme activi ties in serum following electrophoretic fractionation on agarose gel. This can spuriously overestimate the CK-MM fraction and thereby result in underestimation of CK-MM or CK-BB isoenzymes if present. A hemolyz ed serum sample obtained from an elderly patient was erroneously repor ted as containing low CK-MB due to such overestimation of CK-MM fracti on in the sample. Supplementing the AMP already present in the visuali zation reagent formulation, used to estimate CK isoenzyme concentratio n in serum, with Ap5A can eliminate or effectively minimize AK interfe rence, especially that caused by hemolysis, and thereby prevent report ing false-negative CK-MB result obtained with CK isoenzyme electrophor esis assays. (C) 1994 Wiley-Liss, Inc.