title: The carboxylic acid reduction pathway in Nocardia. Purification and characterization of the aldehyde reductase.
abstract: Whole cultures of Nocardia sp. NRRL 5646 reduce carboxylic acids, first to aldehydes, then to alcohols and subsequently to the corresponding acetyl esters. This work describes an NADPH-dependent reductase responsible for catalyzing the reduction of aldehyde intermediates, which was purified 3240-fold by a combination of Mono-Q, hydroxyapatite, and ADP-agarose chromatographies. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the purified enzyme ran as a single band of 47 kDa. A native molecular mass estimated at 101 kDa indicated that the enzyme was a homodimer in the native, active state. Edman degradation indicated a unique N-terminal sequence as NH(2)-X-X-Ala-Ala-Ala-Tyr-Ala-Val-Pro-Ala-Pro-Asp-Gly-Cys-Phe-Glu-Lys-Val-Thr-Ile-Glu-Arg-Arg-Glu-Leu-Gly. The enzyme catalyzed reductions of many aryl- and alkyl-aldehyde substrates. Reactions were most favorable in the direction of aldehyde reduction to alcohols.
authors.affiliation: Division of Medicinal and Natural Products Chemistry, and Center for Biocatalysis and Bioprocessing, College of Pharmacy, University of Iowa, Iowa City, Iowa 52242, USA.
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.forename: John PN
authors.initials: JP
authors.lastname: Rosazza