On the application of affinity chromatography to turnover studies on the lactate dehydrogenase isoenzymes.

1. The suitability of a combined application of the techniques of affinity chromatography, double labelling and gel electrophoresis in the determination of the turnover characteristics of the lactate dehydrogenase isoenzymes (L-lactate:NAD+ oxidoreductase EC 1.1.1.27) in rat tissues has been studied. 2. Affinity chromatography was established as affording the advantages of rapidity, high yield and purity to such studies, and the double-labelling procedure was modified to encompass the differential decay kinetics in the separate rat tissues. In addition, a convenient method for the resolution and separate collection of radioactively labelled isoenzymes has been described. 3. Using this methodology, comparative turnover values for the isoenzymes of lactate dehydrogenase and for total soluble protein have been determined. 4. The comparability of these results with other methodologies, and the advantages of this approach in facilitating broad comparative studies on turnover are discussed.