Purification and properties of an NADPH-linked aldehyde reductase from rat kidney

Rat kidney was shown to contain two NADPH-linked aldehyde reductases (alcohol:NADP+) oxidoreductase, EC 1.1.1.2) with different substrate affinities. The high-Km aldehyde reductase, which was purified to apparent homogeneity, had a molecular weight of 32 000 as determined by Sephadex G-100 gel filtration, and of 37 000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The purified enzyme reduced various aliphatic aldehydes of different carbon-chain lengths besides many chemicals containing aldehyde groups. The Km values for n-hexadecanal and n-octadecanal were 8 microM and 4 microM, respectively. Bovine serum albumin (1.8 mM) stimulated the reduction of n-hexadecanal and n-octadecanal, and increased the Vmax values by about 15-fold without changing the Km values. The kidney enzyme was not distinguishable from the brain and liver high-Km aldehyde reductases in mobility on polyacrylamide gel electrophoresis, immunological properties, peptide maps or substrate specificity.     

Purification and properties of low-Km aldehyde reductase from ox brain

A low-Km aldehyde reductase (alcohol:NADP+ oxidoreductase, EC 1.1.1.2), which may be identical with aldose reductase (alditol:NADP+ 1-oxidoreductase, EC 1.1.1.21), has been purified from ox brain to homogeneity. It was shown to be a monomer with Mr values of 31 000 and 35 100 being obtained by gel filtration and polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate, respectively. The enzyme catalyses the NADPH-dependent reduction of a number of aromatic and sugar aldehydes. The activity of the enzyme with 133 microM NADH was about one-third of that with 120 microM NADPH. Activity with both these coenzymes was optimum at pH 6.2 and was inhibited by increasing the ionic strength with KCl, NaCl or NaNO3. In contrast, the activity was stimulated by sodium phosphate. The activity with NADH as the coenzyme was more sensitive to stimulation by phosphate and to inhibition by increasing ionic strength than that determined with NADPH.     

Isolation and properties of glycerol-3-phosphate oxidoreductase from human placenta

Glycerol-3-phosphate oxidoreductase (sn-glycerol 3-phosphate: NAD+ 2-oxidoreductase, EC 1.1.1.8) from human placenta has been purified by chromatography on 2,4,6-trinitrobenzenehexamethylenediamine-Sepharose, DEAE-Sephadex A-50 and 5'-AMP-Sepharose 4B approximately 15800-fold with an overall yield of about 19%. The final purified material displayed a specific activity of about 88 mumol NADH min-1 mg protein-1 and a single protein band on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The native molecular mass, determined by Ultrogel AcA 44 filtration, was 62000 +/- 2000 whereas the subunit molecular mass, established on polyacrylamide gel in the presence of 0.1% sodium dodecyl sulphate, was 38000 +/- 500. The isoelectric point of the enzyme protein, determined by column isoelectric focusing, was found to be 5.29 +/- 0.09. The pH optimum of the placental enzyme was in the range 7.4-8.1 for dihydroxyacetone phosphate reduction and 8.7-9.2 for sn-glycerol 3-phosphate oxidation. The apparent Michaelis constants (Km) for dihydroxyacetone phosphate, NADH, sn-glycerol 3-phosphate and NAD+ were 26 microM, 5 microM, 143 microM and 36 microM respectively. The activity ratio of cytoplasmic glycerol-3-phosphate oxidoreductase to mitochondrial glycerol-3-phosphate dehydrogenase in human placental tissue was 1:2. The consumption of oxygen by human placental mitochondria incubated with the purified glycerol-3-phosphate oxidoreductase, NADH and dihydroxyacetone phosphate was similar to that observed in the presence of sn-glycerol 3-phosphate. The possible physiological role of glycerol-3-phosphate oxidoreductase in placental metabolism is discussed.     

Purification and characterization of glutamine:fructose 6-phosphate amidotransferase from rat liver

The enzyme glutamine:fructose 6-phosphate amidotransferase (L-glutamine:D-fructose-6-phosphate amidotransferase; EC 2.6.1.16, GFAT) catalyzes the formation of glucosamine 6-phosphate from fructose 6-phosphate and glutamine. In view of the important role of GFAT in the hexosamine biosynthetic pathway, we have purified the enzyme from rat liver and characterized its physicochemical properties in comparison to those from the published microbial enzymes. The purified enzyme has a molecular mass of about 75 kDa as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. On a Sephacryl S-200 gel filtration column, the purified enzyme eluted in a single peak corresponding to a molecular mass of about 280 kDa, indicating that the active enzyme may be composed of four subunits. The N-terminal amino acid sequence of the purified enzyme was determined as X-G-I-F-A-Y-L-N-Y-H-X-P-R, where X indicates an unidentified residue. The K(M) values of the purified enzyme for fructose 6-phosphate and glutamine were 0.4 and 0.8 mM, respectively. The purified enzyme was inactivated by 4, 4'-dithiodipyridine, and the activity of the inactivated enzyme was restored by dithiothreitol. The inactivation followed pseudo first-order and saturation kinetics with the K(inact) of 5.0 microM. Kinetic studies also indicated that 4,4'-dithiodipyridine is a competitive inhibitor of the enzyme with respect to glutamine. Isolation and analysis of the cysteine-modified peptide indicated that Cys-1 was the modified site. Cys-1 has been suggested to play an important role in enzymatic activity of the Escherichia coli enzyme (M. N. Isupov, G. Obmolova, S. Butterworth, M. Badet-Denisot, B. Badet, I. Polikarpov, J. A. Littlechild, and A. Teplyakov, 1996, Structure 4, 801-810).     

Isolation of D-myo-inositol 1:2-cyclic phosphate 2-inositolphosphohydrolase from human placenta

We have isolated D-myo-inositol 1:2-cyclic phosphate 2-inositolphosphohydrolase (EC 3.1.4.36) from human placenta. This enzyme catalyzes the conversion of inositol 1:2-cyclic phosphate to inositol 1-phosphate. The enzyme was purified 1300-fold to apparent homogeneity from the soluble fraction of human placenta. The enzyme requires Mn2+ or Mg2+ ions for activity, has an apparent Km for inositol 1:2-cyclic phosphate of 0.15 mM and forms 2.2 mumol of inositol 1-phosphate/min/mg protein. The enzyme does not utilize the cyclic esters of inositol polyphosphates as substrates. The molecular weight determined by gel filtration chromatography is approximately 55,000. Upon electrophoresis in polyacrylamide gels in sodium dodecyl sulfate, the molecular weight was found to be 29,000 both in the presence and absence of beta-mercaptoethanol. The enzyme was inhibited by inositol 2-phosphate (IC50 = 4 microM) and to a lesser degree by inositol 1-phosphate (IC50 = 2 mM) and inositol (IC50 = 4 mM). Zn2+ is a potent inhibitor of enzyme activity (IC50 = 10 microM). Neither Li+ nor Ca2+ had any effect on enzyme activity. This enzyme may serve to generate inositol from inositol cyclic phosphate metabolites produced by the phosphoinositide signaling pathway in cells.     

Selective overproduction of 5-enol-pyruvylshikimic acid 3-phosphate synthase in a plant cell culture which tolerates high doses of the herbicide glyphosate

Cultured cells of the higher plant Corydalis sempervirens Pers. which had been adapted to growing in the presence of 5 mM glyphosate (N-[phosphonomethyl]-glycine), a herbicide and a potent specific inhibitor of the shikimate pathway enzyme 5-enol-pyruvylshikimate-3-phosphate (EPSP) synthase, had a nearly 40-fold increased level of the extractable activity of EPSP synthase. Activities of five other shikimate pathway enzymes were, however, similar in the adapted and nonadapted cells, and the concentrations of the free aromatic amino acids in the two cell lines were also similar. EPSP synthases purified from glyphosate-adapted, as well as nonadapted cells, had identical physical, kinetic, and immunological properties, which indicated that the glyphosate-sensitive enzyme was overproduced in the adapted culture. Overproduction of EPSP synthase in the adapted culture was unequivocally established by two-dimensional polyacrylamide gel electrophoresis, as well as by one-dimensional sodium dodecyl sulfate-gradient gel electrophoresis and quantitation of EPSP protein by immunoassay after transfer to nitrocellulose membranes. While about 0.06% of the total soluble protein from nonadapted cells was EPSP synthase protein, the proportion was 2.6% in the adapted cells. In vivo pulse-labeling experiments with [35S]methionine established that the adapted cells have an increased rate of EPSP synthase protein synthesis.     

Microbial oxidation of methane and methanol: Purification and properties of a heme-containing aldehyde dehydrogenase from Methylomonas methylovora

Procedures for the purification of an aldehyde dehydrogenase from extracts of the obligate methylotroph, Methylomonas methylovora are described. The purified enzyme is homogeneous as judged from polyacrylamide gel electrophoresis. In the presence of an artificial electron acceptor (phenazine methosulfate), the purified enzyme catalyzes the oxidation of straight chain aldehydes (C₁-C₁₀ tested), aromatic aldehydes (benzaldehyde, salicylaldehyde), glyoxylate, and glyceraldehyde. Biological electron acceptors such as NAD⁺, NADP⁺, FAD, FMN, pyridoxal phosphate, and cytochrome c cannot act as electron carriers. The activity of the enzyme is inhibited by sulfhydryl agents [p-chloromercuribenzoate, N-ethylmaleimide and 5,5-dithiobis (2-nitrobenzoic acid)], cuprous chloride, and ferrour nitrate. The molecular weight of the enzyme as estimated by gel filtration is approximately 45000 and the subunit size determined by sodium dodecyl sulfate-gel electrophoresis is approximately 23000. The purified enzyme is light brown and has an absorption peak at 410 nm. Reduction of enzyme with sodium dithionite or aldehyde substrate resulted in the appearance of peaks at 523 nm and 552 nm. These results suggest that the enzyme is a hemoprotein. There was no evidence that flavins were present as prosthetic group. The amino acid composition of the enzyme is also presented.Non-Standard Abbreviations PMS phenazine methosulfate - DCPIP 2,6-dichlorophenol indophenol - DEAE diethylaminoethyl     

Carboxylic acid reductase: a new tungsten enzyme catalyses the reduction of non-activated carboxylic acids to aldehydes

An enzyme which we call carboxylic acid reductase (aldehyde dehydrogenase) seems to be the first which is able to reduce non-activated carboxylic acids to aldehydes at the expense of reduced viologens. There is no further reduction of the aldehydes to the corresponding alcohols. In the presence of oxidized viologens aldehydes can be dehydrogenated to carboxylic acids roughly 20 times faster than the latter are reduced. The specific enzyme activity in crude extracts is about 100 times increased if 10 microM tungstate and a sulphur source in addition to sulphate is given to the growth medium of Clostridium thermoaceticum. Carboxylic acid reductase seems to be present in two forms. One has an apparent molecular mass of about 240 kDa and is bound to red-Sepharose, whereas, the other, a form of an apparent molecular mass of about 60 kDa, is not bound. SDS gel electrophoresis shows a higher complexity. The very labile enzyme has been enriched by a factor of about 145 by binding to octyl-Sepharose and further chromatographic separation by red-Sepharose and FPLC using Mono-Q and phenyl-Superose columns. After cell growth in the presence of [185W]tungstate, radioactivity coincides with the two forms of enzyme activity during all purification steps. This is also the case when the enzyme is electrophoretically separated on polyacrylamide slab gels.     

Purification and characterization of glyceraldehyde-3-phosphate dehydrogenase from European pilchard Sardina pilchardus

The NAD＋-dependent cytosolic glyceralehyde-3-phosphate dehydrogenase （GAPDH; EC 1.2.1.12） was purified from the skeletal muscle of European pilchard Sardina pilchardus and its physicochemical and kinetic properties were investigated. The purification method consisted of two steps, ammonium sulfate fractionation followed by Blue Sepharose CL-6B chromatography, resulting in an approximately 78-fold increase in specific activity and a final yield of approximately 25%. The Michaelis constants （Kin） for NAD＋ and D-glyceraldehyde-3-phosphate were 92.0 μM and 73.4 μM, respectively. The maximal velocity （Vmax） of the purified enzyme was estimated to be 37.6 U/mg. Under the assay conditions, the optimum pH and temperature were 8.0 and 30 ℃. The molecular weight of the purified enzyme was 37 kDa determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Non-denaturing polyacrylamide gels yielding a molecular weight of 154 kDa suggested that the enzyme is a homotetramer. Polyclonal antibodies against the purified enzyme were used to recognize the enzyme in different sardine tissues by Western blot analysis. The isoelectric point, obtained by an isoelectric focusing system in polyacrylamide slab gels, revealed only one GAPDH isoform （pI 7.9）.     

Purification and properties of aldehyde dehydrogenase from Proteus vulgaris.

NADP-linked aldehyde dehydrogenase (aldehyde : NADP+ oxidoreductase, EC 1.2.1.4) was purified from Proteus vulgaris to the stage of homogeneity as judged by ultracentrifugation and polyacrylamide gel electrophoresis. The molecular weight of the purified enzyme was estimated to be 130000 by gel filtration. The enzyme which was crystallized from ammonium sulfate solution, lost its activity. The enzyme did not require coenzyme A, and the reaction was completely dependent on ammonium ions which could be partially replaced by Rb+ or K+. The optimum pH was about 9. Broad substrate specificity was observed and Km values for propionaldehyde, acetaldehyde and isovaleraldehyde were 1.7 - 10(-5), 4 - 10(-5) and 3 - 10(-5) M, respectively. The physiological role of the enzyme in living cells is obscure, but might account for another degradative pathway of L-leucine in P. vulgaris differing from the established pathway.     

Purification and properties of NADPH-dependent aldehyde reductase from human liver.

An aldehyde reductase (EC 1.1.1.2) from human liver has been purified to homogeneity. The enzyme is NADPH-dependent, prefers aromatic to aliphatic aldehydes as substrates, and is inhibited by barbiturates and hydantoins. The following physicochemical parameters were determined: molecular weight, 36,200; sedimentation coefficient, 2.9 S; Stokes radius, 2.65 nm; isoelectric point, pH 5.3; extinction coefficient at 280 nm, 54,300 M-1 cm-1. Results from polyacrylamide gel electrophoresis with and without sodium dodecyl sulfate, gel filtration, and ultracentrifugation suggest a monomeric structure. On molecule of NADPH binds to the enzyme causing a red shift of the coenzyme absorption maximum from 340 to 352 nm. The amino acid composition has been determined and a partial specific volume of 0.74 was computed from these data. An alpha-helicity of 7 and 18% was estimated from the ellipticities at 208 and 222 nm, respectively. Combination of the most reactive thiol group with p-mercuribenzoate does not cause loss of catalytic activity. Inactivation occurs when more than one thiol group is modified. The presence of NADPH or NADP+ prevents loss of activity by thiol modification. The comparison of structural features of aldehyde reductase with other monomeric and oligomeric dehydrogenases suggest similarities of aldehyde reductase with octopine dehydrogenase.     

Purification and properties of reductases for aromatic aldehydes and ketones from guinea pig liver.

NADPH-dependent enzymatic reduction of aromatic aldehydes and ketones observed in the cytosol of guinea pig liver was mediated by at least three distinct reductases (AR 1, AR 2, and AR 3), which were separated by DEAE-cellulose chromatography. By several procedures AR 2 and AR 3 were purified to homogeneity, but AR 1 could be purified only 30-fold because of the small amount. These enzymes were found to have similar molecular weights of 34,000 to 36,000 and similar Stokes radii of about 2.5 nm. AR 3 was identical to aldehyde reductase [EC 1.1.1.2] in substrate specificity for aromatic aldehydes and D-glucuronate and specific inhibition by barbiturates. AR 1 and AR 2 acted on aromatic ketones and cyclohexanone as well as aromatic aldehydes at optimal pHs of 5.4 and 6.0, respectively, and were immunochemically distinguished from AR 3. AR 1 was the most sensitive to sulfhydryl reagents, and AR 2 was more stable at 50 degrees C than the other enzymes. Similar heterogeneity was observed in the kidney enzymes, but other tissues had little aldehyde reductase activity and contained only AR 3. In addition, lung contained a high molecular weight aromatic ketone reductase different from the above reductases.     

Purification and characterization of glucose 6-phosphate dehydrogenase from Lake Van fish (Chalcalburnus tarichii pallas, 1811) liver

Glucose 6-phosphate dehydrogenase (D-glucose 6-phosphate: NADP+ oxidoreductase, EC 1.1.1.49; G6PD) was purified from Lake Van fish (Chalcalburnus tarichii pallas, 1811) liver, using a simple and rapid method, and some characteristics of the enzyme were investigated. The purification procedure was composed of two steps: homogenate preparation and 2', 5'-ADP Sepharose 4B affinity gel chromatography, which took 7-8 hours. Thanks to the two consecutive procedures, the enzyme, having specific activity of 38 EU/mg protein, was purified with a yield of 44.39% and 1310 fold. In order to control the enzyme purification SDS polyacrylamide gel electrophoresis (SDS-PAGE) was done. SDS polyacrylamide gel electrophoresis showed a single band for enzyme. Optimal pH, stable pH, optimal temperature, Km and, Vmax values for NADP+ and glucose 6-phosphate (G6P) were also determined for the enzyme. In addition, molecular weight and subunit molecular weights were found by sodium dodecyl sulfate polyacrilamide gel electrophoresis (SDS-PAGE) and gel filtration chromatography respectively.     

Affinity purification and properties of porcine brain aldose reductase.

Aldose reductase (alditol:NADP+ 1-oxidoreductase, EC 1.1.1.21) has been purified 1500-fold from porcine brain in a four-step procedure employing Blue-Sepharose 6B affinity chromatography. The purified enzyme was shown to be apparently homogeneous by polyacrylamide gel electrophoresis. The enzyme is a single chain polypeptide of molecular weight 40 000, pH optimum 5.0 K(app)(xylose) 4 mM; K(app)(NADPH) 3 microM. The relative substrate activities, activation with sulfate ion, and limited oxidative and NADH-related reductive activities confirm the classification of this enzyme as aldolase reductase. The activity of the reductase with p-nitrobenzaldehyde and 3-indolacetaldehyde and the similarity of its physical properties with the 'low Km' aldehyde reductase of porcine brain previously reported indicates that these enzymes may be identical.     

Horse liver aldehyde dehydrogenase. Purification and characterization of two isozymes.

Two isozymes of horse liver aldehyde dehydrogenase (aldehyde, NAD oxidoreductase (EC 1.2.1.3)), F1 and F2, have been purified to homogeneity using salt fractionation followed by ion exchange and gel filtration chromatography. The specific activities of the two isozymes in a pH 9.0 system with propionaldehyde as substrate were approximately 0.35 and 1.0 mumol of NADH/min/mg of protein for the F1 and F2 isozymes, respectively. The multiporosity polyacrylamide gel electrophoresis molecular weights of the F1 and F2 isozymes were approximately 230,000 and 240,000 respectively. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis gave subunit molecular weight estimates of 52,000 and 53,000 for the F1 and F2 isozymes, respectively. The amino acid compositions of the two isozymes were found to be similar; the ionizable amino acid contents being consistent with the electrophoretic and chromatographic behavior of the two isozymes. Both isozymes exhibited a broad aldehyde specificity, oxidizing a wide variety of aliphatic and aromatic aldehydes and utilized NAD as coenzyme, but at approximately 300-fold higher coenzyme concentration could use NADP. The F1 isozyme exhibited a very low Km for NAD (3 muM) and a higher Km for acetaldehyde (70 muM), while the F2 isozyme was found to have a higher Km for NAD (30 muM) and a low Km for acetaldehyde (0.2 muM). The two isozymes showed similar chloral hydrate and p-chloromercuribenzoate inhibition characteristics, but the F1 isozyme was found to be several orders of magnittude more sensitive to disulfiram, a physiological inhibitor of acetaldehyde oxidation. Based on its disulfiram inhibition characteristics, it has been suggested that the F1 isozyme may be the primary enzyme for oxidizing the acetyldehyde produced during ethanol oxidation in vivo.     

Characterization of methylglyoxal synthase in Saccharomyces cerevisiae

Methylglyoxal synthase in Saccharomyces cerevisiae was purified approximately 300 folds from cell extracts with 20% of activity yield. During purification procedures, polymorphic behaviours of the enzyme were observed. The purified enzyme was homogeneous on polyacrylamide gel electrophoresis and consisted of a single polypeptide chain of Mr = 26,000. The enzyme was most active at pH 9.5-10.5 and strictly specific to dihydroxyacetone phosphate with Km = 3 mM. Phosphoenolpyruvate, glyceraldehyde-3-phosphate, orthophosphate and thiol compounds were potent inhibitors of the enzyme.     

Benzyl alcohol metabolism by Pseudomonas putida: a paradox resolved

Evidence is presented for the existence in Pseudomonas putida of two NAD-linked dehydrogenases that function sequentially to oxidize benzyl alcohol. Induction of muconate lactonizing enzyme, a 3-oxoadipate pathway enzyme, indicated that P. putida oxidized benzyl alcohol to benzoate. Polyacrylamide gel electrophoresis with activity staining and enzymatic assays for an NAD-dependent dehydrogenase both showed that cells contained a single, constitutive alcohol dehydrogenase capable of oxidizing benzyl alcohol. This enzyme was shown to have the same specificity in extracts of glucose-grown as in benzy alcoholgrown cells. An NAD-aldehyde dehydrogenase oxidized benzaldehyde but was most active with normal alkyl aldehydes. This aldehyde dehydrogenase was shown to be induced, by enzymatic assays and by activity staining of polyacrylamide gel electropherograms, not only in cells grown on benzyl alcohol, but also in cells grown on ethanol. These experiments suggested that the aldehyde dehydrogenase was induced by the alcohol being oxidized rather than the substrate aldehyde.In sum, the evidence from enzyme assays and polyacrylamide gel electrophoresis of extracts indicates that Pseudomonas putida catabolizes benzyl alcohol slowly when it is the sole carbon and energy source, by the action of a constitutive, nonspecific, alcohol dehydrogenase and an alcohol-induced, nonspecific aldehyde dehydrogenase to yield benzoate, which is further metabolized via the 3-oxoadipate (beta-ketoadipate) pathway.In memory of R. Y. Stanier     

Initial characterization of aldehyde dehydrogenase from rat testis cytosol

Aldehyde dehydrogenase was purified 187-fold from cytosol of rat testis by chromatographic methods and gel filtration with a yield of about 50%. The enzyme exhibits absolute requirement for exogenous sulfhydryl compounds and strong dependence on temperature. Addition of 0.4mM Ca2 or Mg2 ions results in 50% inhibition. Optimally active at pH 8.5 and 50 degrees C, aldehyde dehydrogenase displays broad substrate specificity; saturation curves with acetaldehyde and propionaldehyde are non-hyperbolic, with Hill coefficients comprised between 0.8 and 0.7. Strong substrate inhibition can be observed with both aromatic and long-chain alyphatic aldehydes. According to mathematical models, Km decreases from 246 microM for acetaldehyde to 4 microM for capronaldehyde and Ki decreases from about 4mM for butyraldehyde to 0.2 mM for capronaldehyde.     

Purification to homogeneity of rat liver dinucleoside tetraphosphatase by affinity elution with adenosine 5'-tetraphosphate

Starting from a partially purified dinucleoside tetraphosphatase (Np4Nase; EC 3.6.1.17), we developed an affinity elution purification protocol involving the strong competitive inhibitor adenosine 5'-tetraphosphate. Np4Nase bound to Cibacron Blue F3G-A-Sepharose 4B or to Reactive Blue 2-Sepharose CL-6B was specifically eluted with 10 microM adenosine 5'-tetraphosphate and 5 mM MgCl2, but not by either of them separately. The final Np4Nase preparation was homogeneous by sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by Coomassie blue or silver staining. The protein band showed an apparent 18 kDa molecular mass. The specific activity of the homogeneous Np4Nase was about 150 units/mg, meaning a 45,000-fold increase and a 10% recovery with respect to the crude extract. After preparative polyacrylamide gel electrophoresis, protein visualization with KCl, fragmentation of the gel lane, and extraction, all the renatured Np4Nase activity was found associated to the 18 kDa band. The renatured enzyme showed the same Km value for diadenosine 5',5"'-P1,P4-tetraphosphate as the partially purified or the native homogeneous Np4Nase.     

Purification, characterization, and properties of an aryl aldehyde oxidoreductase from Nocardia sp. strain NRRL 5646.

An aryl aldehyde oxidoreductase from Nocardia sp. strain NRRL 5646 was purified 196-fold by a combination of Mono-Q, Reactive Green 19 agarose affinity, and hydroxyapatite chromatographies. The purified enzyme runs as a single band of 140 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular mass was estimated to be 163 +/- 3.8 kDa by gel filtration, indicating that this enzyme is a monomeric protein. The binding of the enzyme to Reactive Green 19 agarose was Mg2+ dependent. The binding capacity was estimated to be about 0.2 mg of Reactive Green agarose per ml in the presence of 10 mM MgCl2. This enzyme can catalyze the reduction of a wide range of aryl carboxylic acids, including substituted benzoic acids, phenyl-substituted aliphatic acids, heterocyclic carboxylic acids, and polyaromatic ring carboxylic acids, to produce the corresponding aldehydes. The Km values for benzoate, ATP, and NADPH were determined to be 645 +/- 75, 29.3 +/- 3.1, and 57.3 +/- 12.5 microM, respectively. The Vmax was determined to be 0.902 +/- 0.04 micromol/min/mg of protein. Km values for (S)-(+)-alpha-methyl-4-(2-methylpropyl)-benzeneacetic acid (ibuprofen) and its (R)-(-) isomer were determined to be 155 +/- 18 and 34.5 +/- 2.5 microM, respectively. The Vmax for the (S)-(+) and (R)-(-) isomers were 1.33 and 0.15 micromol/min/mg of protein, respectively. Anthranilic acid is a competitive inhibitor with benzoic acid as a substrate, with a Ki of 261 +/- 30 microM. The N-terminal and internal amino acid sequences of a 76-kDa peptide from limited alpha-chymotrypsin digestion were determined.