title: Characterization of two aldo-keto reductases from Gluconobacter oxydans 621H capable of regio- and stereoselective alpha-ketocarbonyl reduction.
abstract: Two cytosolic NADPH-dependent carbonyl reductases from Gluconobacter oxydans 621H, Gox0644 and Gox1615, were heterologously produced in Escherichia coli. The recombinant proteins were purified to homogeneity and characterized. Gox0644 and Gox1615 were dimers with native molecular masses of 66.1 and 74.5 kDa, respectively. The enzymes displayed broad substrate specificities and reduced alpha-ketocarbonyls at the keto moiety most proximal to the terminus of the alkyl chain to produce alpha-hydroxy carbonyls, as demonstrated by NMR. With respect to stereoselectivity, protein Gox0644 specifically reduced 2,3-pentanedione to 2R-hydroxy-pentane-3-one, whereas Gox1615 produced 2S-hydroxy-pentane-3-one. Both enzymes also reduced 1-phenyl-1,2-propanedione to 2-hydroxy-1-phenylpropane-1-one, which is a key intermediate in the production of numerous pharmaceuticals, such as antifungal azoles and antidepressants. Gox0644 displayed highest activities with 2,3-diones, alpha-ketoaldehydes, alpha-keto esters, and 2,5-diketogluconate. Gox1615 was less active with these substrates, but displayed a broader substrate spectrum reducing a variety of alpha-diketones and aldehydes.
authors.affiliation: Institute für Mikrobiologie und Biotechnologie, 168 Meckenheimer Allee, 53115, Bonn, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Schweiger
authors.forename: Harald
authors.initials: H
authors.lastname: Gross
authors.forename: Uwe
authors.initials: U
authors.lastname: Deppenmeier
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000449:Aldehyde Reductase; D000447:Aldehydes / Q000737:chemistry / Q000378:metabolism; D000074408:Aldo-Keto Reductases; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020600:Gluconobacter oxydans / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D007659:Ketones / Q000737:chemistry* / Q000378:metabolism; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010422:Pentanones / Q000737:chemistry / Q000378:metabolism; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D000447:Aldehydes; D001426:Bacterial Proteins; D007659:Ketones; D010422:Pentanones; D000429:Alcohol Oxidoreductases; D000074408:Aldo-Keto Reductases; D000449:Aldehyde Reductase; C013186:2,3-pentanedione