Simultaneous separation of serum creatine kinase and lactate dehydrogenase isoenzymes by ion-exchange column chromatography.

Lactate dehydrogenase isoenzymes were partially separated by use of a previously described column technique for creatine kinase [Clin. Chem. 20, 36 (1974)]. Extracts of lactate dehydrogenase-rich tissues were used to evaluate column resolution. Samples layered on mini-columns containing DEAE-Sephadex were eluted with Tris-buffered sodium chloride (100 and 200 mmol/liter). Lactate dehydrogenase activity in column effluents was measured by the Wacker method, and their isoenzyme content was assessed by electrophoresis on polyacrylamide gel. Dehydrogenase isoenzymes 3, 4, and 5 were separated from isoenzymes 1 and 2, and the separation was tissue-specific and reproducible. The electrophoretic technique for isoenzymes 3, 4, and 5 gave values about 20% lower than did the column technique. Sera from 15 healthy laboratory technicians contained total lactate dehydrogenase, isoenzymes 1 and 2, and isoenzymes 3, 4, and 5 in the ranges 94 to 152, 34 to 64, and 38 to 75 U/liter, respectively. Activities of sera from 15 patients with acute myocardial infarction (total lactate dehydrogenase) ranged from 212 to 800 U/liter and lactate dehydrogenase isoenzymes 1 and 2 ranged from 138 to 628 U/liter. Lactate dehydrogenase and creatine kinase isoenzymes were rapidly and easily measured after being simultaneously separated. The procedure is specific and sensitive for following the post-infarct time course of changes in isoenzyme activities.