Purification and catalytic properties of liver alcohol dehydrogenase isoenzymes in patients with hepatoma in Nigeria.

Alcohol dehydrogenase isoenzymes were isolated from the liver of patients with hepatoma and healthy control individuals. Whereas only a single form of the enzyme was obtained in healthy control liver, two distinct forms of the enzyme were found in hepatoma liver. These two forms were named AD-I and AD-II according to their elution pattern in CM-cellulose chromatography and mobility towards the anode in polyacrylamide gel electrophoresis. Both isoenzymes resembled normal liver enzyme with respect to their molecular properties. However, the two forms had distinct kinetic properties, although AD-I had some properties similar to the normal liver enzyme. The Km values of AD-I for ethanol, n-butanol and m-nitrobenzyl alcohol were 61 microM, 90 microM and 292 microM, respectively, as against the values for AD-II which were 473 microM, 100 microM and 60 microM for the respective substrates. Pyrazole inhibited the activity of AD-II but not that of AD-I. These kinetic properties of alcohol dehydrogenase in patients with hepatoma could be of clinical importance particularly in the tropics where the disease is prevalent.