Heterogeneity of chicken liver cytosolic aspartate aminotransferase.

The isolated native molecular forms of chicken liver cytosolic aspartate aminotransferase give rise to two kinds of generation processes: (a) on storage, molecular forms are transformed into a series of variants with increasing anodic mobilities; and (b) addition of thiol reagents not only avoids the process, but causes the partial transformation of minor subforms into variants with higher isoelectric point values. In both cases the mobilities of each generated variant coincide with that of the corresponding native molecular form. The variants generated either by storage or in the presence of thiol reagents were separated by chromatofocusing. Several comparative studies have demonstrated the structural and functional identity between native molecular forms and 'in vitro' active generated variants of the enzyme. The results obtained suggest that native minor subforms arise from the major alpha form due to oxidation process and might represent intermediate species in the intracellular cytosolic aspartate aminotransferase turnover.