Mammalian aspartate aminotransferases(AST·EC·2·6·1·1) exist in two predominant forms: one mitochondrial (AST-m) the other of cytosolic origin (AST-c). The electrophoretic migration rate of AST-c is between α-and β-glubulin. and the electrophoretic migration rate of AST-m is similar to γ-glubulin. The method of solid blue B dye with electrophoresis on agarose is not sensitive to AST-m. So the nitroblue tetrazolium (NBT) dye is used instead of the solid blue B dye.