title: The two alcohol dehydrogenases of Zymomonas mobilis. Purification by differential dye ligand chromatography, molecular characterisation and physiological roles.
abstract: The two alcohol dehydrogenases found in Zymomonas mobilis have each been purified using dye-ligand chromatography and affinity elution with nucleotides. The isoenzyme with lower electrophoretic mobility (ZADH-1) is a zinc enzyme with properties essentially similar to preparations described elsewhere. The faster isoenzyme (ZADH-2) accounted for some 90% of the ethanol-oxidizing activity in freshly prepared extracts and corresponded to the iron-activated enzyme previously described. This enzyme was inactivated by zinc; activity could only be retained during purification by including either ferrous ions or cobaltous ions in the buffers. ZADH-2 has relatively low acetaldehyde reductase activity; consequently ZADH-1 is responsible for about half of the physiological activity (acetaldehyde reduction) in Zymomonas cells. Kinetic studies showed that ZADH-2 is activated by ethanol in both reaction directions; a hypothesis for the mechanism of activation is presented. Metal ion analyses of ZADH-2 prepared in the presence of iron or cobalt indicated one atom of the relevant metal per subunit, with no significant zinc content. N-terminal sequence analyses showed that the ZADH-1 has some homology with the Bacillus stearothermophilus enzyme, whereas ZADH-2 resembles the yeast enzyme more closely.
mesh_terms: D000426:Alcohol Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000145:classification / Q000302:isolation & purification*; D000595:Amino Acid Sequence; D002846:Chromatography, Affinity; D004396:Coloring Agents; D004789:Enzyme Activation / Q000187:drug effects; D006090:Gram-Negative Bacteria / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000032:analysis; D007527:Isoenzymes / Q000302:isolation & purification*; D007700:Kinetics; D008970:Molecular Weight
chemical_list: D004396:Coloring Agents; D007527:Isoenzymes; D007501:Iron; D000429:Alcohol Oxidoreductases; D000426:Alcohol Dehydrogenase