title: Purification and properties of a secondary alcohol dehydrogenase from the parasitic protozoan Tritrichomonas foetus.
abstract: A novel secondary alcohol dehydrogenase has been isolated from Tritrichomonas foetus, the protozoan parasite which is responsible for bovine trichomonal abortion. The enzyme has been obtained in apparently homogeneous form after a 120-fold purification from cell homogenates, thus indicating that this activity constitutes an unusually high 1% of the total cytosolic protein. The native Mr = 115,000, determined by polyacrylamide gel electrophoresis. Mobility on sodium dodecyl sulfate gels suggests that the enzyme is composed of 6-8 subunits, identical as to molecular size (Mr = 17,000). The enzyme catalyzes the reversible oxidation of 2-propanol to acetone, using NADP+ (and not NAD+) as the redox-active co-substrate. Other small secondary alcohols, such as 2-butanol, 2- and 3-pentanol, cyclobutanol, and cyclopentanol are substrates, as are the corresponding ketones of these alcohols. Primary alcohols, such as ethanol and 1-propanol, are oxidized at rates less than 5% of that observed for 2-propanol. Product inhibition studies demonstrate an ordered kinetic mechanism, wherein the co-substrate (NADP+/NADPH) binds to the enzyme prior to binding of the substrate (alcohol/ketone).
authors.forename: D E
authors.initials: DE
authors.lastname: Kleiner
authors.forename: M
authors.initials: M
authors.lastname: Johnston
mesh_terms: D000079:Acetaldehyde / Q000378:metabolism; D000426:Alcohol Dehydrogenase; D000429:Alcohol Oxidoreductases / Q000302:isolation & purification*; D000818:Animals; D006863:Hydrogen-Ion Concentration; D007659:Ketones / Q000378:metabolism; D007700:Kinetics; D046911:Macromolecular Substances; D008433:Mathematics; D008970:Molecular Weight; D014318:Tritrichomonas / Q000201:enzymology*
chemical_list: D007659:Ketones; D046911:Macromolecular Substances; D000429:Alcohol Oxidoreductases; D000426:Alcohol Dehydrogenase; D000079:Acetaldehyde