How accurate are lactate dehydrogenase isoenzyme estimations by the thin-layer agarose fluorescent technique?

We offer an assessment of the accuracy of the thin-layer agarose fluorescent technique of Elevitch et al. [Am. J. Clin. Pathol. 46, 692 (1966)]. We used semi-purified human lactate dehydrogenase isoenzymes 1 and 5. Both the lactate lead to pyruvate and pyruvate lead to lactate assays [Clin. Chem. 20, 1462 (1974)] appear to give, within the errors of the techniques used, a substantially unbiased estimate of both LD-1 and LD-5, although this must remain a provisional conclusion until a definitive method of assay for the total and isoenzymic LD activities is created. Introducing a buffer into the substrate mixture (lactate lead to pyruvate assay) had no effect on these findings except at extremes of pH, when marked inaccuracies occurred.