Creatine kinase reactivation by thiol compounds.

It is now commonly accepted that thiol activated creatine kinase (CK) assay systems measure CK activity more accurately and more reproducibly than non-activated systems. However, some differences have arisen in the literature in regards to the nature and course of CK activation. Some thiol compounds have been reported to yield higher enzyme activities than others. Dalal et al. (1) reported that mercaptoethanol at 6.5 mM is suboptimal in the Siegel and Cohen assay (2); whereas, dithiothreitol (DTT) at 4 mM yields maximum activity. Warren has shown that DTT and mercaptoethanol produce significantly greater CK activities than cysteine, dithioerythritol (DTE), glutathione, or mercaptoacetate (3). Bishop et al. (4) and Kar and Pearson (5) reported that CK was equally activated independent of the thiol activator. We report here our findings on the relative effectiveness of mercaptoethanol, cysteine, glutathione, and DTT in the reactivation of serum CK using the Oliver-Rosalki method (6,7) and some characteristics of the reaction process.