ALCOHOL-DEHYDROGENASE OF CLASS-I - KIWI LIVER-ENZYME, PARALLEL EVOLUTION IN SEPARATE VERTEBRATE LINES, AND CORRELATION WITH 12S RIBOSOMAL-RNA PATTERNS

Alcohol dehydrogenase class I from kiwi liver has been purified, analy zed, and compared with that of other alcohol dehydrogenases, The resul ts show that several avian and mammalian forms of the enzyme exhibit p arallel evolutionary patterns in two independent lineages of a single protein, establishing a pattern in common, Furthermore, the data corre late the enzyme evolutionary pattern with that of 12S rRNA. Biological ly, the patterns complement those on ratite and other avian relationsh ips, Functionally, the enzyme has a low K-m with ethanol and a branche d-chain residue at position 141, like the mammalian enzymes but in con trast to the other characterized ratite enzyme (with Ala-141 and a hig her K-m). This pattern of natural variability suggests a frequent but not fully complete correlation between a large residue size at positio n 141 and tight ethanol binding.