Abstract:

Objective　 To evaluate the performance of mitochondrial aspartate aminotransferase (m-AST) by enzyme inhibition method, and to investigate the clinical significance of m-AST in patients with liver disease. Methods 　The m-AST activity was determined by enzyme inhibition method, and the activity of cytosolic aspartate aminotransferase (c-AST) was inhibited by protease, and was determined by rate method. The results of enzyme inhibition method were compared with those of immune suppression method. A total of 259 patients with liver disease (43 patients with acute hepatitis, 95 patients with chronic viral hepatitis, 20 patients with liver failure, 11 patients with serious hepatitis, 40 patients with compensated liver cirrhosis, 9 patients with decompensated liver cirrhosis and 41 patients with primary liver carcinoma) and 220 healthy subjects (healthy control group) were enrolled. Serum m-AST activity was measured by enzyme inhibition method and evaluated. The m-AST activities were compared with aspartate aminotransferase (AST) activities. Results　 The within-run coefficient of variation (CV) of enzyme inhibition method was 0.59%-2.23%. The between-run CV was 5.24%-6.23%. The recovery rates were 101.6%-108.0% (the average recovery rate was 104.97%). The linear equation was Y=0.997X-1.51, r=0.999 9. The linearity was up to 450 U/L. The activity of 1500 U/L concentration of c-AST was inhibited completely. The data was positively correlated between enzyme inhibition method and immune suppression method (r=0.999 8). Hemolysis had interference to the m-AST determination results. According to 95% confidence interval (±1.96s), the reference range of m-AST in males was 3.1-9.5 U/L, and that in females was 2.5-8.7 U/L. The activity of m-AST in liver disease group was higher than that in healthy control group (P<0.05), and was positively correlated with AST activity. The ratio of m-AST to AST in healthy control group was 0.30±0.07, and the ratio in liver disease group was lower than that in healthy control group (P<0.05). The decrease degree of m-AST/AST ratio was lower than that of m-AST. Conclusions　 Enzyme inhibition method for m-AST activity had the advantages of high automation, reliability and wide linear range. The m-AST activity can reflect the degree of liver cell injury. It has significance on clinical classification and prognosis of liver disease.

Key words: Mitochondrial aspartate aminotransferase, Aspartate aminotransferase, Enzyme inhibition method, Liver disease