Independent quantitation of the mitochondrial and the cytosolic isoenzyme of aspartate aminotransferase in chicken tissues by radioimmunoassays.

Two specific and sensitive radioimmunoassays for the independent determination of the cytosolic and mitochondrial isoenzyme of aspartate aminotransferase from chicken are described. The assays use 125I-labeled aspartate aminotransferases as tracer antigens, rabbit antisera, and goat anti-rabbit IgG antisera for indirect immunoprecipitation. The detection limit for the cytosolic isoenzyme was 177 pg and for the mitochondrial isoenzyme 83 pg. The assays were used for measuring the concentrations of the aspartate aminotransferase isoenzymes in serum, cultured fibroblasts, and various tissues of chicken. Both isoenzymes in the different tissue extracts proved immunologically identical with the corresponding isoenzymes isolated from heart.