Lability of human creatine kinase isoenzymes at 37 degrees C: a complication of electrophoretic separation.

The activity of the brain specific isoenzyme of creatine kinase is shown to fall off rapidly at 37 degrees C, particularly in the presence of albumin. Dithiothreitol cannot reverse this lability. The implications of this finding suggest that electrophoretic techniques which use incubation methods to detect the brain specific isoenzyme of creatine kinase may underestimate the true activity.