Biochemical genetics of alcohol dehydrogenase isozymes in the gray short-tailed opossum (Monodelphis domestica)

Abstract

Polyacrylamide gel-isoelectric focusing (PAGE-IEF) methods were used to examine the multiplicity, tissue distribution, and biochemical genetics of alcohol dehydrogenase (ADH) isozymes among gray short-tailed opossums (Monodelphis domestica). Seven ADH isozymes were resolved and distinguished on the basis of their isoelectric points, tissue distributions, and substrate and inhibitor specificities. ADH1 and ADH2 exhibited Class I properties and were observed in liver (and intestine) extracts. ADH3, ADH4, and ADH5 showed "high-Km" (possibly Class IV) properties, with ADH3 and ADH4 exhibiting high activity in cornea, ear, stomach, and esophagus extracts. ADH6 and ADH7 exhibited Class III properties, including activities as formaldehyde dehydrogenases, with each showing different tissue distribution characteristics; ADH6 was widely distributed, and ADH7 was restricted to prostate extracts. An additional form of formaldehyde dehydrogenase (FDH) was observed, which was inactive with hexenol and ethanol as substrates. Isoelectric point variants were observed for ADH3 (three forms) and for ADH4 (two forms), and the inheritance of ADH3 was studied in 15 families of M. domestica. The data were consistent with codominant inheritance of two alleles (ADH3*A and ADH3*B) at a single autosomal locus (designated ADH3) and with a model involving a dimeric ADH isozyme: ADH3 (gamma 2 isozyme, forming three dimers designated gamma 1(2), gamma 1 gamma 2, and gamma 2(2) in heterozygous individuals).