Optimization of methods for aspartate aminotransferase and alanine aminotransferase.

Abstract

Conditions for accurate measurement of catalytic activity of aspartate aminotransferase and alanine aminotransferase in human serum have been reinvestigated. The basic variables (kind of buffer, buffer concentration, pH, ion effects, and the influence of pyridoxal-5-phosphate) can now be considered optimized. On this basis, the kinetic parameters of both aminotransferases were determined, i.e., Michaelis and inhibitor constants for substrates and reaction products. With a mathematical approach for two-substrate enzyme reactions the substrate concentrations were calculated from the viewpoints "most economical," "most convenient," and "lowest variability." Also the conditions for the indicator reactions have been newly defined with respect to a kinetic model. All calculated data were rechecked experimentally and it can be shown that both approaches fully agree. Furthermore, we show that the mathematical approach allows more precise recommendations for optimized methods. For technical reasons, the catalytic activity of aspartate aminotransferase in human serum can only be measured as a 0.96 fraction of its theoretical maximum velocity, the catalytic activity of alanine aminotransferase as a 0.91 fraction. The assay conditions for a Reference Method are finally described and recommendations are made for optimized routine methods for determination of the catalytic activity of these transferases in human serum.

Excessive Accumulation of Hepatic Copper in LEC Rats Aged 80 Days without Hepatitis and 130 Days with Hepatitis

“…Biochemical evaluation of liver function was determined by measuring serum enzyme activities of aspartate aminotransferase (GOT) and alanine aminotransferase (GPT). GOT and GPT activities were measured by the reduction of NADH, added as a coenzyme (Bergmeyer et al 1978). Urea nitrogen (BUN) in serum was measured for evaluation of renal function.…”

Hepatotoxicity of Hornet's Venom Sac Extract in Isolated Perfused Rat Liver

“…Enzyme assays. Enzymes activities (ALT, ALP, AST, LDH and GGT) were determined in the perfused medium with an EN1 GEMSAEC centrifugal analyzer at 30" (Bergmeyer et al 1978). AST, ALT and LDH were measured at 340 nm.…”

Effect of dietaryCurcuma longaon enzymatic and immunological profiles of rohu,Labeo rohita(Ham.), infected withAeromonas hydrophila

“…The measurement of ALP (EC 3.1.3.1) of serum was performed as per the recommended method of German Society of Clinical Chemistry (1972) The activities of AST (EC 2.6.1.1) and ALT (EC 2.6.1.2) in serum were estimated using the methods of Bergmeyer, Scheibe and Wahlefeld (1978) and Bergmeyer and Hoarder (1980) respectively.…”