CEPHALOPOD ALCOHOL-DEHYDROGENASE - PURIFICATION AND ENZYMATIC CHARACTERIZATION

Octopus, squid and cuttle-fish organs were examined for alcohol dehydr ogenase activity. Only one form was detectable, with properties typica l of mammalian class III alcohol dehydrogenase. The corresponding prot ein was purified from octopus and enzymatically characterized. Ion-exc hange and affinity chromatography produced a pure protein in excellent yield (73%) after 1600-fold purification. Enzymatic parameters with s everal substrates were similar to those for the human class III alcoho l dehydrogenase, demonstrating a largely conserved function of the enz yme through wide lines of divergence covering vertebrates, cephalopods and bacteria. The results establish the universal occurrence of class III alcohol dehydrogenase and its strictly conserved functional prope rties in separate living forms. The absence of other alcohol dehydroge nases in cephalopods is compatible with the emergence of the ethanol-a ctive class I type at a later stage, in lineages leading to vertebrate s.