Induction of rat liver cytoplasmic aldehyde dehydrogenase by phenobarbital and polycyclic hydrocarbons. Comparison of different isoenzyme types.

The induction of rat liver cytoplasmic aldehyde dehydrogenase by some xenobiotics and phenobarbital are compared. An acute and a chronic treatment with polycyclic hydrocarbons and with TCDD produce a similar pattern of induced enzymes in isoelectric focusing. The result is clearly different from induction with phenobarbital in the genetically selected rat strain. Another main activity in cytoplasm consists of three different isoenzyme patterns which evidently are normal enzyme types. The induced enzyme of liver cytoplasm after chronic AAF-treatment was purified to homogeneity. The enzyme had a molecular weight of 90000 and a subunit molecular weight of 45000. It had Km-values in the millimolar range for aliphatic aldehydes and in the micromolar range for aromatic aldehydes. Both NAD and NADP were coenzymes of the purified aldehyde dehydrogenase.