New automated measurement of mitochondrial aspartate aminotransferase with use of protease 401.
Total mitochondrial aspartate aminotransferase (EC 2.6.1.1), the sum of apo- and holo-mitochondrial aspartate aminotransferase activity in human serum, was measured by using a proteolytic method: inactivation of cytosolic aspartate aminotransferase with cytosolic aspartate aminotransferase-inactivating protease 401 from Streptomyces violaceochromogenes. Cytosolic aspartate aminotransferase is completely inactivated, and apo-mitochondrial aspartate aminotransferase is completely activated by pyridoxal 5'-phosphate within 5 min. Results by the proposed method correlated well with those by an immunochemical method (r = 0.994, n = 145) and showed excellent inhibitory activity of the protease for holo- and apo-cytosolic aspartate aminotransferase up to 5000 U/L and activation of mitochondrial apo-aspartate aminotransferase up to 2000 U/L in the presence of 100 mumol of pyridoxal 5'-phosphate per liter. Within-run Cvs were good (1.13-7.49%). Mean values for total mitochondrial aspartate aminotransferase and apo-mitochondrial aspartate aminotransferase activities in serum of the healthy subjects were 4.8 (SD 0.9) and 1.8 (SD 0.8) U/L, respectively (n = 154). Various common interferents tested did not affect this assay.
Watazu
Y
Y
Department of Laboratory Medicine, Kumamoto University Medical School, Japan.
Uji
Y
Y
Sugiuchi
H
H
Okabe
H
H
Murao
S
S
D001219:Aspartate Aminotransferases / Q000037:antagonists & inhibitors / Q000097:blood*; D001322:Autoanalysis; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D008930:Mitochondria, Liver / Q000201:enzymology*; D010447:Peptide Hydrolases; D011732:Pyridoxal Phosphate; D013302:Streptomyces / Q000201:enzymology
D007202:Indicators and Reagents; D011732:Pyridoxal Phosphate; D001219:Aspartate Aminotransferases; D010447:Peptide Hydrolases