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The separation of lactate dehydrogenase isoenzymes by zone electrophoresis using cellulose acetate strips as support was dependent on the concentration of the buffer used (5 mM and 50 mM, pH 7.4) and on the source of the material (chicken liver or guinea-pig liver). In three different 5 mM buffer systems, pH 7.4 (phosphate, veronal and Tris-HC1) the four lactate dehydrogenase isoenzymes present in chicken liver cytosol: M3H, M2H2, MH3 and H4 were resolved into four separated bands. M3H and M2H2 isoenzymes migrated towards the cathode whereas the other two isoenzymes showed anodic mobilities. In 50 mM buffers, pH 7.4 all enzyme activity appeared as a single band with anodic mobility similar to that of H4. Guinea-pig liver isoenzymes were well resolved in both buffer conditions and appeared as five bands with anodic mobilities. The different behaviour of the lactate dehydrogenase isoenzymes in 5 mM and 50 mM buffers can not be assigned to ionic strength effects but it may explained by assuming the ...

Four staining methods for aspartate aminotransferase (AAT) detection after electrophoresis have been reported. Comparison of the minimum AAT activity detected by these methods showed the following sequence: Sakakibara et al.> Rej and Herder > Decker and Rau > Banks et al. Addition of ADP and diaphorase to the stain of Banks increased its sensitivity 10 fold. The presence of lactate dehydrogenase (LDH > activity in the samples gave electrophoretical artifacts when the methods of Banks et al. and Rej & HoSrder were used. These artifacts were due to the nothing dehydrogenase (NoDH) activity of LDH as demonstrated by chromatography on 5′ AMP-Sepharose 4B (LDH affinity support). Comparative studies were carried out with cytosolic AATases from human, rat and chicken livers. The methods which used cystains sulfinic acid as amino donor (Sakakibara et al.) or Fast Violet B as stain (Decker & Rau) were the sole really specific for the evaluation of AAT activity in biological extracts.