title: Isolation and purification of aspartate aminotransferase isoenzymes from human liver by chromatography and isoelectric focusing.
abstract: To purify cytoplasmic and mitochondrial isoenzymes of aspartate aminotransferase (EC 2.6.1.1) from human liver. We used heat treatment, ammonium sulfate precipitation, anion- and cation-exchange chromatography, affinity chromatography, and isoelectric focusing. Final preparations of the isoenzymes were homogeneous, with specific activities of 198 and 208 kU/g for the cytoplasmic and the mitochondrial enzymes, respectively. The mitochondrial isoenzyme focused as a single band with a pl value of 9.60, whereas the cytoplasmic isoenzyme had subforms with pl values of 5.22, 5.42, and 5.62 at 4 degrees C. In Tris . HCl buffer, both isoenzymes have an activity maximum at pH 7.8. In [bis(2-hydroxyethyl)amino]tris(hydroxymethyl)methane (Bistris) buffer, however, the mitochondrial isoenzyme also showed an optimum pH of 6.7.
mesh_terms: D001219:Aspartate Aminotransferases / Q000302:isolation & purification*; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange / Q000379:methods; D003600:Cytosol / Q000201:enzymology; D006801:Humans; D007525:Isoelectric Focusing / Q000379:methods; D007527:Isoenzymes / Q000302:isolation & purification*; D008099:Liver / Q000201:enzymology*; D008930:Mitochondria, Liver / Q000201:enzymology
chemical_list: D007527:Isoenzymes; D001219:Aspartate Aminotransferases