Lung alcohol and aldehyde dehydrogenase isoenzymes in Chinese

Abstract

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) isoenzyme phenotypes were determined in 53 surgical lung specimens by isoelectric focusing. ADH isoenzymes containing beta subunits, but no alpha, gamma or pi subunits, were found present in human lungs. Ninety percent of the lung specimens exhibited a pH-optimum for ethanol oxidation at pH 8.5, instead of 10.5 which is usual among Caucasians. The homozygous ADH2 2-2 phenotype was found to be 60%, and the heterozygous ADH2 2-1 phenotype, 30%. The remaining 10% of the lungs, exhibiting a pH-optimum 10.5, was homozygous ADH2 1-1 phenotype. Accordingly, the gene frequencies of the alleles ADH2(2) and ADH1(2) were calculated to be 0.75 and 0.25, respectively. Fifty-five percent of the 53 lungs examined possessed both the activities of ALDH I and ALDH II isoenzymes, whereas 45% lacked the ALDH I activity. The ADH activities in homogenate supernatants of the lungs with phenotypes ADH2 2-2 or ADH2 2-1 were considerably greater than those with ADH2 1-1 phenotypes. The ALDH activities were significantly higher in the ALDH I-positive lungs than in the ALDH I-negative groups. The implications of these distributions of lung ADH and ALDH isoenzyme composition and activity among Orientals for ethanol metabolism and toxicity are discussed.