SEARCH · Search PubMed

Results for “NADP”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 433 records · Page 24Linked to original sources

PubMed1995

Human placental 17 beta-hydroxysteroid dehydrogenase: secondary structure and circular dichroism demonstration of conformational changes upon NADP binding.

The secondary structure of human placental 17 beta-hydroxysteroid dehydrogenase in the absence and presence of NADP has been studied by circular dichroism spectroscopy. The conformational analysis of the NADP-containing enzyme shows that is an alpha/beta protein with 60% of regular secondary structure (38% of alpha helix, 22% of beta-strand structures), 20% of beta-turn and 20% of non-repetitive structure. These results were in good agreement with the information obtained using statistical and homology methods based on amino-acid sequence. On the other hand, 25% alpha-helix, 55% beta-strand, and 20% non-repetitive structure were estimated by circular dichroism for the cofactor-free enzyme. Addition of varying concentrations of NADP to the cofactor free enzyme is accompanied by circular dichroism spectral changes. From the variation in the magnitude of the positive band at 193 nm with increasing NADP concentration, a dissociation constant of 34 nM was obtained.

17-Hydroxysteroid Dehydrogenases↗

PubMed1994

Purification and characterization of a NADP+/NADPH-specific flavoprotein that is overexpressed in FdI- strains of Azotobacter vinelandii.

Earlier studies have established that mutant strains of Azotobacter vinelandii that do not synthesize ferredoxin I (AvFdI) overexpress another protein designated Protein X (Morgan, T. V., Lundell, P. J., and Burgess, B. K. (1988) J. Biol. Chem. 263, 1370-1375). This protein has now been purified using two-dimensional gel electrophoresis as an assay. The purified protein is a monomer with M(r) approximately 29,000 which degrades slowly to a specific M(r) approximately 22,000 form when stored in solution. The native protein is bright yellow and contains noncovalently attached FAD that is reduced by either dithionite or NADPH without formation of a stable semiquinone. Titration with NADP+/NADPH gives an E0' value of approximately -327 mV versus SHE. Because this E0' is so close to that of the NADP+/NADPH couple it is not clear if Protein X is an NADPH oxidase or an NADP+ reductase in vivo. Comparison of the NH2-terminal sequence and other properties of Protein X with those of other proteins, suggests that it is likely to be related to the Escherichia coli ferredoxin NADP+ reductase (the fpr gene product), and affinity chromatography shows that Protein X binds specifically to AvFdI.

Amino Acid Sequence↗

PubMed1996

NADP-malic enzyme isoforms in maize leaves.

Two isoforms of NADP-malic enzyme have been characterized in maize leaves. The 72 kDa-form of the protein, present mainly in etiolated maize leaves, has lower specific activity than the 62 kDa-form, which is implicated in C4 metabolism and predominates in green leaves. The larger form of the enzyme has higher Km values for NADP and malate and lower PH optimum. The antibodies raised against the 62 kDa-form of the protein react with the 72 kDa-form. Steady state levels of NADP-malic enzyme, as measured by the amount of protein and activity, increase several-fold when dark-grown maize seedlings are illuminated. This increase in protein is about 13-fold for the 62 kDa-form of the enzyme, while the 72 kDa-form remains practically constant after a transient increase. Northern blot analysis using a specific probe against the 62 kDa-form of the enzyme, reveals the increase of a 2.2 kb mRNA during greening. Southern hybridization analysis with genomic DNA suggests the presence of more than one gene encoding NADP-malic enzyme in maize. In this paper we provide biochemical and inmunological evidence suggesting that both isoforms are closely related and that the 72 kDa-form is also present in low levels in mature green leaves.

Amino Acid Sequence↗

PubMed1999

Apo and holo crystal structures of an NADP-dependent aldehyde dehydrogenase from Streptococcus mutans.

The aldehyde dehydrogenases (ALDHs) are a superfamily of multimeric enzymes which catalyse the oxidation of a broad range of aldehydes into their corresponding carboxylic acids with the reduction of their cofactor, NAD or NADP, into NADH or NADPH. At present, the only known structures concern NAD-dependent ALDHs. Three structures are available in the Protein Data Bank: two are tetrameric and the other is a dimer. We solved by molecular replacement the first structure of an NADP-dependent ALDH isolated from Streptococcus mutans, in its apo form and holo form in complex with NADP, at 1.8 and 2.6 A resolution, respectively. Although the protein sequence shares only approximately 30 % identity with the other solved tetrameric ALDHs, the structures are very similar. However, a large local conformational change in the region surrounding the 2' phosphate group of the adenosine moiety is observed when the enzyme binds NADP, in contrast to the NAD-dependent ALDHs. Structure and sequence analyses reveal several properties. A small number of residues seem to determine the oligomeric state. Likewise, the nature (charge and volume) of the residue at position 180 (Thr in ALDH from S. mutans) determines the cofactor specificity in comparison with the structures of NAD-dependent ALDHs. The presence of a hydrogen bond network around the cofactor not only allows it to bind to the enzyme but also directs the side-chains in a correct orientation for the catalytic reaction to take place. Moreover, a specific part of this network appears to be important in substrate binding. Since the enzyme oxidises the same substrate, glyceraldehyde-3-phosphate (G3P), as NAD-dependent phosphorylating glyceraldehyde-3-phosphate dehydrogenases (GAPDH), the active site of GAPDH was compared with that of the S. mutans ALDH. It was found that Arg103, Arg283 and Asp440 might be key residues for substrate binding.

Aldehyde Oxidoreductases↗

PubMed1993

Isolation and characterization of a cDNA encoding NADP(+)-specific isocitrate dehydrogenase from soybean (Glycine max).

A cDNA that encodes an NADP-specific isocitrate dehydrogenase (IDH) was cloned from a soybean nodule cDNA library by complementation of an Escherichia coli mutant that lacked IDH. DNA sequence analysis showed that the 1583 bp soybean cDNA could encode a protein that shares 63.9% amino acid sequence identity with the Saccharomyces cerevisiae NADP-IDH and long sequences of identity to an IDH from pig. Southern blot analysis suggests that this gene corresponds to a gene family made up of no more than two loci. The IDH cDNA hybridized to a 1.7 kb soybean mRNA and the relative amount of this transcript in soybean leaves, nodules and roots was 1:3.4:7.7. In alfalfa, a 1.7 kb mRNA was also found but the ratios for the corresponding tissues were 1:7.4:7.7. IDH activity was detected in the complemented E. coli strain and the electrophoretic mobility of this activity in nondenaturing polyacrylamide gels was identical to that of an IDH in extracts from soybean cotyledons or nodule cytosol. NADP-IDH specific activity in the E. coli host strain varied with growth phase; the highest rates (ca. 180 nmol/min per mg protein) were observed in late-stationary-phase cells. The enzyme had a broad pH optimum of 8.0 to 9.5 and had an absolute metal cofactor requirement, preferring Mn2+ below pH 8.0 and Mg2+ above pH 8.0. The Km for isocitrate and NADP was 21 microM and 11 microM respectively with Mn2+ as cofactor and 13 microM and 12 microM with Mg2+ as cofactor.

Amino Acid Sequence↗

PubMed1992

A prediction of the three-dimensional structure of maize NADP(+)-dependent malate dehydrogenase which explains aspects of light-dependent regulation unique to plant enzymes.

A model has been built for the plant NADP-malate dehydrogenase from Zea mays, a key enzyme in photosynthesis, which undergoes light-dependent regulation. The model was based on sequence and presumed structural homology to the known three-dimensional structure of mammalian porcine cytosolic NAD-malate dehydrogenase. A cystine-loop present in an extended C-terminal region of plant NADP-malate dehydrogenases was modelled using molecular mechanics and computer graphical methods, based on the assumption that a disulphide bridge exists in the inactive form of the enzyme between Cys351 and Cys363. The predicted conformation of the intact C-terminal cystine-loop suggests that the extended polypeptide will bind in the active centre and inhibit enzyme activity. Another ionizable cysteine residue in the active site is predicted to control the charge of the catalytic His215 and might be responsible for the uniquely tight binding of the positively charged nicotinamide ring of NADP+ in this and other C4 and C3 plant NADP-malate dehydrogenases.

Amino Acid Sequence↗

PubMed1992

Aluminum: a pH-dependent inhibitor of NADP-isocitrate dehydrogenase from porcine heart.

Aluminum showed a pH-dependent inhibitory effect on NADP-isocitrate dehydrogenase from porcine heart. Aluminum ions (Al3+) acted as a partial competitive inhibitor of the enzyme with respect to the substrate threo-Ds-isocitrate and inhibited the enzyme non-competitively with respect to NADP at pH 6.85. Fractional velocity plot analysis showed the Ki of the enzyme for aluminum ions to be 0.88 microM. When pH was elevated to 8.0, aluminum ions, which occur as a form of the Al(OH)4- anion, acted as partial uncompetitive and non-competitive inhibitors of the enzyme with respect to the substrates isocitrate and NADP, respectively. The Kí of the enzyme was determined to be 5.64 microM at pH 8.0 by fractional velocity plot analysis. The inhibition of NADP-isocitrate dehydrogenase by two forms of aluminum ions may explain aluminum toxicity in various tissues and organs.

Aluminum↗

PubMed1988

Limited proteolysis of inactive tetrameric chloroplast NADP-malate dehydrogenase produces active dimers.

Carboxy-terminal amino acids of NADP-dependent malate dehydrogenase (EC 1.1.1.82) from pea chloroplasts were removed by treatment with carboxypeptidase Y. This results in the activation of the inactive oxidized enzyme, while activation by light in vivo is thought to occur via reduction of an intrasubunit disulfide bridge. After proteolytic activation the oxidized enzyme had a specific activity of 100 U/mg protein, which is 50% of the maximal activity of the control enzyme in the reduced state. When the truncated enzyme was reduced with dithiothreitol (DTT), the specific activity was further increased to 1200 U/mg. While the native enzyme is composed of four identical subunits of 38,900 Da, the truncated malate dehydrogenase forms dimers composed of two subunits of 38,000 Da. No further change of molecular mass or activity was noticed subsequent to prolonged incubation of native NADP-malate dehydrogenase with carboxypeptidase Y for several days. When the enzyme is denatured by 2 M guanidine-HCl, the proteolytic activation proceeds more rapidly, but only transiently. The truncated enzyme is less accessible to activation by reduced thioredoxin, but the stimulation of activity by DTT alone is more rapid than that of the native enzyme. These results indicate that only a small carboxy-terminal peptide of native NADP-malate dehydrogenase from pea chloroplasts is accessible to proteolytic degradation and that this peptide is involved in the regulation of activity, tetramer formation, and thioredoxin binding. While the pH optimum for catalytic activity of the intact reduced enzyme is at pH 8.0-8.5, it is shifted to more acidic values upon proteolysis of NADP-malate dehydrogenase. At pH values below 8 the reduced truncated enzyme exhibits substrate inhibition by oxaloacetate.

Amino Acids↗

PubMed1992

NADP-malic enzyme from plants.

NADP-malic enzyme functions in plant metabolism as a decarboxylase of malate in the chloroplast or cytosol. It serves as a source of CO2 for photosynthesis in the bundle sheath chloroplasts of C4 plants and in the cytosol of Crassulacean acid metabolism plants, and as a source of NADPH and pyruvate in the cytosol of various tissues. Mg2+ or Mn2+ is required as a cofactor. The enzyme has a high specificity and low Km for NADP+. It exists as a tetramer which may undergo changes in oligomerization and exhibit hysteresis. Its kinetic properties vary depending on the compartmentation and function of the enzyme. The chloroplast form in C4 plants has a high pH optimum (pH 8) under high malate, which favours the tetramer, whereas lower pH (pH 7) favours the dimer form. Generally, other forms of the enzyme, which are thought to be cytosolic, have lower pH optima than the chloroplast enzyme. In a number of cases these forms have been shown to have allosteric properties with malate as a substrate. Chemical modifications of the plant enzyme suggest sulphydryl, histidine and arginine residues are required for catalysis. Primary sequence studies on the chloroplastic enzyme from C4 plants show significant similarities to cytosolic NADP-ME in plants and animals, including a sequence motif which is indicative of the NADP+ binding site. The possible origin of the chloroplast form of the enzyme is discussed.

Amino Acid Sequence↗

PubMed1994

Redox regulation of maize NADP-malic enzyme by thiol-disulfide interchange: effect of reduced thioredoxin on activity.

Incubation of C4 NADP-malic enzyme from maize leaves with the oxidant o-iodosobenzoate leads to the reversible and complete inactivation of the enzyme. The time-course of inactivation is biphasic with the rate depending on the o-iodosobenzoate concentration. The inactivation is partially prevented by L-malate, NADP and Mg2+ alone, while NADP plus Mg2+ afford total protection. The complete reversal of the inactivation by the reductive agents dithiothreitol and 2-mercaptoethanol suggests that the modification of the enzyme by o-iodosobenzoate occurs concomitant with the oxidation of one or more pairs of sulfhydryl groups to the disulfide state, producing a conformationally altered form of the protein or directly modifying the active site. Titration of free thiol groups before and after inactivation of maize malic enzyme by o-iodosobenzoate shows a decrease in the accessible groups from 7 to 5, suggesting inactivation is accompanied by oxidation of two vicinal thiols. The oxidized form of the enzyme is rapidly reactivated by incubation with chemical and photochemically reduced thioredoxin in vitro, while the 'dark' activity of the enzyme is enhanced to the level of the 'light' activity by dithiothreitol. This evidence suggests that a reversible reduction and oxidation of disulfide bonds may take place during the regulation of the enzyme, indicating that the redox state of the disulfide bonds of C4 NADP-malic enzyme from maize leaves is important for the expression of maximal catalytic activity.

Disulfides↗

PubMed1987

Mitochondrial NADP-dependent malic enzyme of cod heart. Rate of forward and reverse reaction.

The mitochondrial NADP-dependent malic enzyme (EC 1.1.1.40) was purified about 300-fold from cod Gadus morhua heart to a specific activity of 48 units (mumol/min)/mg at 30 degrees C. The possibility of the reductive carboxylation of pyruvate to malate was studied by determination of the respective enzyme properties. The reverse reaction was found to proceed at about five times the velocity of the forward rate at a pH 6.5. The Km values determined at pH 7.0 for pyruvate, NADPH and bicarbonate in the carboxylation reaction were 4.1 mM, 15 microM and 13.5 mM, respectively. The Km values for malate, NADP and Mn2+ in the decarboxylation reaction were 0.1 mM, 25 microM and 5 microM, respectively. The enzyme showed substrate inhibition at high malate concentrations for the oxidative decarboxylation reaction at pH 7.0. Malate inhibition suggests a possible modulation of cod heart mitochondrial NADP-malic enzyme by its own substrate. High NADP-dependent malic enzyme activity found in mitochondria from cod heart supports the possibility of malate formation under conditions facilitating carboxylation of pyruvate.

Animals↗

PubMed1999

Purification, properties and enhanced expression under nitrogen starvation of the NADP+-isocitrate dehydrogenase from the cyanobacterium Phormidium laminosum.

Nitrogen starvation enhances up to 8-fold the cellular level of the NADP+-dependent isocitrate dehydrogenase activity (isocitrate:NADP+ oxidoreductase (decarboxylating), IDH, EC 1.1.1.42) in the thermophilic filamentous non-N2-fixing cyanobacterium Phormidium laminosum. The enzyme was purified 650-fold to electrophoretic homogeneity from nitrogen-starved cells with an activity yield of 25% and a specific activity of 500 U (mg protein)-1. The native enzyme showed a pI of 5.9 and it was a dimer of 107 kDa consisting of two identical subunits of 53 kDa. The activity required the presence of a divalent metal cation as an essential activator, Mn2+ or Mg2+ being the most effective. The optimum temperature for activity was 55 degrees C and the Ea for catalysis was 39.7 kJ mol-1. An optimum pH for activity of 8.5 was found and the calculated pKE1, pKE2 and pKES1 of enzyme ionisation groups were 6.0, 8.9 and 6.3, respectively. Km values of 22, 50 and 24 microM were calculated for d,l-isocitrate, NADP and Mn2+, respectively, in the Mn2+-dependent reaction and 70, 32 and 159 microM for d,l-isocitrate, NADP and Mg2+, respectively, in the Mg2+-dependent reaction. The decarboxylating activity was inhibited by ATP, ADP and by its reaction products 2-oxoglutarate and NADPH2. Polyclonal antibodies raised against the pure IDH were used to assess the presence of the enzyme in cells subjected to nitrogen starvation.

Cyanobacteria↗

PubMed2000

Structural and kinetic characterization of NADP-dependent, non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase from celery leaves.

NADP-dependent, non-phosphorylating glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.9) from celery leaves was purified over 1200-fold to a specific activity of 35 units/mg protein, and its kinetic, regulatory and structural properties were characterized. The purified enzyme exhibited a homotetrameric structure with a subunit molecular mass of 54 kDa. A high specificity of the enzyme for the substrates NADP(+) (K(m)=7 µM) and D-glyceraldehyde-3-phosphate (K(m)=127 µM) was observed. Maximal activity was determined at pH 8.5. The purified enzyme was highly unstable, requiring the addition of NADP(+) or conditions of high ionic strength in the medium. A hysteretic behavior, with a lag phase of minutes, was observed during activity measurement of the enzyme preincubated in the absence of substrates. The lag was inversely proportional to the protein concentration during preincubation. The hysteretic parameters were affected by the substrates, KCl and mannitol among other compounds. Distinctively, incubation with NADP(+) produced a near twofold activation of the enzyme. Results suggest that in alditol producing plants the enzyme plays a key role in the synthesis and partitioning of photoassimilates.

Journal Article↗

PubMed1988

Isotope effect studies of chicken liver NADP malic enzyme: role of the metal ion and viscosity dependence.

The role of the metal ion in the oxidative decarboxylation of malate by chicken liver NADP malic enzyme and details of the reaction mechanism have been investigated by 13C isotope effects. With saturating NADP and the indicated metal ion at a total concentration 10-fold higher than its Km, the following primary 13C kinetic isotope effects at C4 of malate [13(V/Kmal)] were observed at pH 8.0: Mg2+, 1.0336; Mn2+, 1.0365; Cd2+, 1.0366; Zn2+, 1.0337; Co2+, 1.0283; Ni2+, 1.025. Knowing the partitioning of the intermediate oxalacetate between decarboxylation to pyuvate and reduction to malate allows calculation of the intrinsic carbon isotope effect for decarboxylation. For Mg2+ as activator, this was 1.049 with NADP and 1.046 with 3-acetylpyridine adenine dinucleotide phosphate, although the intrinsic primary deuterium isotope effects on dehydrogenation were 5.6 and 4.2, and the partition ratios of the oxalacetate intermediate for decarboxylation as opposed to hydride transfer were 0.11 and 3.96 (the result of the different redox potentials of NADP and the acetylpyridine analogue). The close agreement of the intrinsic 13C isotope effects with each other and with the 13C isotope effect for the Mg2+-catalyzed nonenzymatic decarboxylation of oxalacetate of 1.0489 [Grissom, C. B., & Cleland, W. W. (1986) J. Am. Chem. Soc. 108, 5582] indicates a similarity of transition states for these reactions. It was not possible to calculate reasonable intrinsic carbon isotope effects with the other metal ions by use of the partitioning ratio of oxalacetate because of decarboxylation by another mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1982

Reconstruction of the chloroplast noncyclic electron transport pathway from water to NADP with three integral protein complexes.

RECONSTRUCTION OF PHOTOSYNTHETIC NONCYCLIC ELECTRON TRANSPORT FROM WATER TO NADP HAS BEEN ACCOMPLISHED BY USING THREE INTEGRAL PROTEIN COMPLEXES ISOLATED FROM CHLOROPLAST THYLAKOID MEMBRANES: photosystems I and II and the cytochrome b(6)-f complex. This system shows an absolute dependence on the presence of all three protein complexes for NADP reduction, in addition to plastocyanin, ferredoxin, and ferredoxin-NADP reductase. The reconstructed system was found to be sensitive to low concentrations of known inhibitors of noncyclic electron transport. Depletion of the Rieske iron-sulfur center and bound plastoquinone from the cytochrome b(6)-f complex resulted in an inhibition of the photoreduction of NADP.

Journal Article↗

PubMed2000

Identification by mutagenesis of arginines in the substrate binding site of the porcine NADP-dependent isocitrate dehydrogenase.

Pig heart mitochondrial NADP-dependent isocitrate dehydrogenase is the most extensively studied among the mammalian isocitrate dehydrogenases. The crystal structure of Escherichia coli isocitrate dehydrogenase and sequence alignment of porcine with E. coli isocitrate dehydrogenase suggests that the porcine Arg(101), Arg(110), Arg(120), and Arg(133) are candidates for roles in substrate binding. The four arginines were separately mutated to glutamine using a polymerase chain reaction method. Wild type and mutant enzymes were each expressed in E. coli, isolated as maltose binding fusion proteins, then cleaved with thrombin, and purified to yield homogeneous porcine isocitrate dehydrogenase. The R120Q mutant has a specific activity, as well as K(m) values for isocitrate, Mn(2+), and NADP(+) similar to wild type enzyme, indicating that Arg(120) is not needed for function. The specific activities of R101Q, R110Q, and R133Q are 1.73, 1.30, and 19.7 micromols/min/mg, respectively, as compared with 39.6 units/mg for wild type enzyme. The R110Q and R133Q enzymes exhibit K(m) values for isocitrate that are increased more than 400- and 165-fold, respectively, as compared with wild type. The K(m) values for Mn(2+), but not for NADP(+), are also elevated indicating that binding of the metal-isocitrate complex is impaired in these mutants. It is proposed that the positive charges of Arg(110) and Arg(133) normally strengthen the binding of the negatively charged isocitrate by electrostatic attraction. The R101Q mutant shows smaller, but significant increases in the K(m) values for isocitrate and Mn(2+); however, the marked decrease in k(cat) suggests a role for Arg(101) in catalysis. The V(max) of wild type enzyme depends on the ionized form of an enzymic group of pK 5.5, and this pK(aes) is similar for the R101Q and R120Q enzymes. In contrast, the pK(aes) for R110Q and R133Q enzymes increases to 6.4 and 7.4, respectively, indicating that the positive charges of Arg(110) and Arg(133) normally lower the pK of the nearby catalytic base to facilitate its ionization. These results may be understood in terms of the structure of the porcine NADP-specific isocitrate dehydrogenase generated by the Insight II Modeler Program, based on the x-ray coordinates of the E. coli enzyme.

Amino Acid Sequence↗

PubMed2003

Cardiac mitochondrial NADP+-isocitrate dehydrogenase is inactivated through 4-hydroxynonenal adduct formation: an event that precedes hypertrophy development.

Mitochondrial NADP+-isocitrate dehydrogenase activity is crucial for cardiomyocyte energy and redox status, but much remains to be learned about its role and regulation. We obtained data in spontaneously hypertensive rat hearts that indicated a partial inactivation of this enzyme before hypertrophy development. We tested the hypothesis that cardiac mitochondrial NADP+-isocitrate dehydrogenase is a target for modification by the lipid peroxidation product 4-hydroxynonenal, an aldehyde that reacts readily with protein sulfhydryl and amino groups. This hypothesis is supported by the following in vitro and in vivo evidence. In isolated rat heart mitochondria, enzyme inactivation occurred within a few minutes upon incubation with 4-hydroxynonenal and was paralleled by 4-hydroxynonenal/NADP+-isocitrate dehydrogenase adduct formation. Enzyme inactivation was prevented by the addition of its substrate isocitrate or a thiol, cysteine or glutathione, suggesting that 4-hydroxynonenal binds to a cysteine residue near the substrate's binding site. Using an immunoprecipitation approach, we demonstrated the formation of 4-hydroxynonenal/NADP+-isocitrate dehydrogenase adducts in the heart and their increased level (210%) in 7-week-old spontaneously hypertensive rats compared with control Wistar Kyoto rats. To the best of our knowledge, this is the first study to demonstrate that mitochondrial NADP+-isocitrate dehydrogenase is a target for inactivation by 4-hydroxynonenal binding. Furthermore, the pathophysiological significance of our finding is supported by in vivo evidence. Taken altogether, our results have implications that extend beyond mitochondrial NADP+-isocitrate dehydrogenase. Indeed, they emphasize the implication of post-translational modifications of mitochondrial metabolic enzymes by 4-hydroxynonenal in the early oxidative stress-related pathophysiological events linked to cardiac hypertrophy development.

Aldehydes↗

PubMed1993

An inducible NADP(+)-dependent D-phenylserine dehydrogenase from Pseudomonas syringae NK-15: purification and biochemical characterization.

An inducible NADP(+)-dependent D-phenylserine dehydrogenase [EC 1.1.1.-], which catalyzes the oxidation of the hydroxyl group of D-threo-beta-phenylserine, was purified to homogeneity from a crude extract of Pseudomonas syringae NK-15 isolated from soil. The enzyme consisted of two subunits identical in molecular weight (about 31,000). In addition to D-threo-beta-phenylserine, it utilized D-threo-beta-thienylserine, D-threo-beta-hydroxynorvaline, and D-threonine as substrates but was inert towards other isomers of beta-phenylserine and threonine. It showed maximal activity at pH 10.4 for the oxidation of D-threo-beta-phenylserine, and it required NADP+ as a natural coenzyme. NAD+ showed a slight coenzyme activity. The enzyme was inhibited by p-chloromercuribenzoate, HgCl2, and monoiodoacetate but not by the organic acids such as tartronate. The Michaelis constants for D-threo-beta-phenylserine and NADP+ were 0.44 mM and 29 microM, respectively. The N-terminal 27 amino acids sequence was determined. It suggested that the NADP(+)-binding site was located in the N-terminal region of the enzyme.

Alcohol Oxidoreductases↗