Imperial S, Quiroga C, Busquets M, Cortés A
Departament de Bioquímica i Fisiologia, Facultat de Química, Universitat de Barcelona, Spain.
Biochim Biophys Acta. 1991 Mar 8;1077(1):72-8. doi: 10.1016/0167-4838(91)90527-7.
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.
(a) 在储存时，分子形式会转化为一系列阳极迁移率增加的变体；(b) 添加硫醇试剂不仅可以避免该过程，还会导致次要亚形式部分转化为等电点值更高的变体。在这两种情况下，每个生成变体的迁移率都与相应天然分子形式的迁移率一致。通过色谱聚焦分离了通过储存或在硫醇试剂存在下生成的变体。多项比较研究表明，该酶的天然分子形式与“体外”活性生成变体之间在结构和功能上具有同一性。所得结果表明，天然次要亚形式是由于氧化过程从主要α形式产生的，可能代表细胞内胞质天冬氨酸转氨酶周转的中间物种。
