Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.1.1.37 (malate dehydrogenase)
4,591 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A dependence is established for the activity of NADP-dependent isocytrate dehydrogenase and malate dehydrogenase as well as of NAD-malate dehydrogenase on the carbonic acid level. When the biocarbonate concentration in rabbit blood and tissues rise, the activity of cytoplasmic NADP-isocytrate dehydrogenase and NADP-malate dehydrogenase of the liver lowers. The analogous regularity is observed in the in vitro experiments when the bicarbonate concentrations in the medium rises up to 40 mM (within the physiological limits). The activity of NAD-malate dehydrogenase in the soluble fraction of the rabbit liver and kidney increases with the bicarbonate level within the same limits. The found dependence was confirmed in experiments with the enzyme crystalline preparations.
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PMID:[Effect of different levels of carbonic acid on activity of dehydrogenases]. 3 5

1. Oxalacetase from Asperigillus niger was found to be an inducible enzyme, the induction being dependent not only on neutralisation of the acidic growth medium but also on the presence of carbonate. An explanation is proposed. 2. Three methods were established for the quantitative determination of oxalacetase activity. These are based on the determination of the product acetate, on the absorbance of oxaloacetate and on coupling the hydrolysis of oxaloacetate to the oxidation of malate by NAD in the presence of malate dehydrogenase. 3. Oxalacetase was purified about 50-fold from cell-free extracts of A. niger and used to determine some of its properties such as kinetic constants. 4. 2S-[U-14C, 3-2H2] Malate in the presence of oxalacetase, NAD and malate dehydrogenase was partially converted to acetate and oxalate. The 3H/14C ratio of the isolated acetate was nearly twice as high as that of the malate used initially. The result demonstrates that the keto form of oxaloacetate, not the enol, is the substrate of the enzyme. 5. Equimolecular mixtures of 2S, 3S-[3-2H1] malate + 2S-[2-2H1] malate (mixture 1) and 2S, 3R-[3-2H1, 3H1] malate + 2S, 3R-[2-2H1, 3-3H1] malate (mixture 2) were prepared from 2S-[3-3H2] malate by incubation with fumarase in normal and tritiated water, respectively. The isolated mixture 1, in the presence of oxalacetase, NAD and malate dehydrogenase was incubated in tritiated water for formation of acetate and oxalate; the isolated mixture 2 was treated likewise in normal water. 6. The mixtures of symmetrically labelled [3H1] acetate and chiral acetates thus produced were isolated and the configuration of the [3H1, 3H1] acetate specimens was determined in the sequence acetate leads to malate leads to fumarate, as usual. The [2H1, 3H1] acetate derived from 2S, 3S-[3-2H1] malate (present in mixture 1( yielded a malate which on incubation with fumarase retained 65.0% of its total tritium content. This chiral acetate, therefore, had the R configuration. The [2H1, 3H1] acetate derived from 2S, 3R-[2-2H1, 3-3H1] malate produced a malate which retained 35% of its total tritium content, and therefore had the S configuration. 7. It was concluded that the detachment of the oxaloyl residue from oxaloacetate and its replacement by a proton proceed with inversion of configuration at the methylene group which becomes methyl during the hydrolysis.
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PMID:Partial purification and some properties of oxalacetase from Aspergillus niger. 17 20

The rate of reactions catalyzed by the NADP-dependent isocytrate dehydrogenase and malate dehydrogenase soluble fraction of the rat liver was studied as affected by carbonic acid. The reaction initial rate for both enzymes was determined under normal conditions and at physiological concentrations of carbonic acid. The initial rate of the direct isocytrate dehydrogenase reaction is established to decrease by 20, 35 and 57% at the carbonic acid concentrations 20, 40 and 60 mM. At the same time the initial rate of the malate dehydrogenase reactions increases by 51, 86 and 104% at the same levels of carbonic acid.
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PMID:[Effect of carbon dioxide on the initial rate of the isocitrate and malate dehydrogenase reactions in rat liver]. 42 39

Malate dehydrogenase, reputed to be a soluble matricial enzyme, is shown to be also strongly associated with the inner membrane, in pig heart mitochondria. Repeated sonications, water washes, freezing-thawing cycles are not very effective to remove malate dehydrogenase activity from inner membranes, which whatever the treatment, remains important. This activity is only partly solubilized by the substrates, malate or oxaloacetate. High ionic strength treatments by either NaCl-carbonate or 3M KCl have a strong effect, but they also remove cytochrome c oxidase and rotenone-sensitive NADH-cytochrome c reductase, reputed inner membrane intrinsic enzymes, thus strongly damaging the inner membrane. After the action of phospholipase A from Naja Naja Venom, the residual activity is about twenty per cent and only phosphatidyl choline and phosphatidyl ethanolamine decreased significantly, the other phospholipids being unchanged. It is suggested that the enzyme is deeply buried in the membrane and mainly interacts with phosphatidyl choline.
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PMID:The markers of pig heart mitochondrial sub-fractions. II. - On the association of malate dehydrogenase with inner membrane. 75 79

We describe an enzymatic method, requiring only 10 mul of serum, for determining CO2 as bicarbonate or dissolved gas. Phosphoenolpyruvate carboxylase catalyzes the reaction of HCO3- with phosphoenolypyruvate to give oxalacetate. The resulting NADH, in the presence of malate dehydrogenase, is oxidized to NAD+, and the decrease in absorbance at 340 nm is directly proportional to the amount of CO2 present in the sample. Reaction is complete in 3 to 6 min under assay conditions, and is linearly related to CO2 concentrations between 8 and 65 mmol/liter. Analytical recovery is 95-110% (average, 101%). Two laboratories compared values obtained by continuous-flow analysis. The resulting correlation coefficients were 0.966 and 0.987, values for the t-test were t(paired) equals 0.473 and t(paired) equals 0.334, and average day-to-day precisions (three concentrations) were 3.9% and 4.2%.
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PMID:Enzymatic method for determination of CO2 in serum. 124 28

In addition to the normal carboxylation reaction, phosphoenolpyruvate carboxylase from Zea mays catalyzes a HCO3(-)-dependent hydrolysis of phosphoenolpyruvate to pyruvate and Pi. Two independent methods were used to establish this reaction. First, the formation of pyruvate was coupled to lactate dehydrogenase in assay solutions containing high concentrations of L-glutamate and aspartate aminotransferase. Under these conditions, oxalacetic acid produced in the carboxylation reaction was efficiently transaminated, and decarboxylation to form spurious pyruvate was negligible. Second, sequential reduction of oxalacetate and pyruvate was achieved by initially running the reaction in the presence of malate dehydrogenase with NADH in excess over phosphoenolpyruvate. After the reaction was complete, lactate dehydrogenase was added, thus giving a measure of pyruvate concentration. At pH 8.0 in the presence of Mg2+, the rate of phosphoenolpyruvate hydrolysis was 3-7% of the total reaction rate. The hydrolysis reaction catalyzed by phosphoenolpyruvate carboxylase was strongly metal dependent, with rates decreasing in the order Ni2+ greater than Co2+ greater than Mn2+ greater than Mg2+ greater than Ca2+. These results suggest that the active site metal ion binds to the enolate oxygen, thus stabilizing the proposed enolate intermediate. The more stable the enolate, the less reactive it is toward carboxylation and the greater the opportunity for hydrolysis.
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PMID:Hydrolysis of phosphoenolpyruvate catalyzed by phosphoenolpyruvate carboxylase from Zea mays. 163 56

An enzymatic method for measuring total carbon dioxide content in freeze-clamped animal tissues is described. Total carbon dioxide content [TCO2] was defined as the sum of the dissolved CO2, the bicarbonate concentration, and the carbonate concentration. Tissue was extracted in 80% methanol, 20 mM 2-amino-2-methyl-1-propanol, pH 9.5 at 25 degrees C and homogenized in a 1.5-ml Sardstat screw-top test tube containing 0.5-mm glass beads and a minibead beater. Total CO2 was determined as bicarbonate/carbonate by monitoring the oxidation of NADH at 340 nm using the coupled assay of phosphoenolpyruvate carboxylase (EC 4.1.1.31) and malate dehydrogenase (EC 1.1.1.37). In the coupled assay system, 1 mumol of bicarbonate/carbonate consumed is equivalent to the oxidation of 1 mumol NADH at 340 nm. The assay medium comprised 50 mM 2-amino-2-methyl-1-propanol, pH 9.0 at 25 degrees C, 5 mM phosphoenolpyruvate (PEP), 0.25 mM NADH, 5 mM MgCl2, 5 mM mercaptoethanol, 0.02% bovine serum albumin, 10 mM oxamate, PEP carboxylase (0.5 units/ml), and malate dehydrogenase (0.5 units/ml). The total CO2 content measured in freeze-clamped rat heart, liver, brain, and skeletal muscle was 20.53 +/- 0.64, 17.34 +/- 0.67, 17.00 +/- 0.48, 16.06 +/- 0.53 mumol/g wet wt tissue, respectively (n = 5). The total CO2 in the crusher muscle of the lobster was found to be 5.0 +/- 0.33 mumol/g wet wt. Total CO2 was also enzymatically measured in arterial plasma from four chronically cannulated male wistar rats and was 24.65 +/- 1.81 mumol/ml plasma.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enzymatic determination of total CO2 in freeze-clamped animal tissues and plasma. 175 Jun 72

13C-NMR spectroscopy was used to determine the level of cytoplasmic malate in maize root tips that exhibited different rates of malate synthesis. Intracellular malate was 13C-labeled at carbons 1 and 4 by perfusing root tips with 5 nM H13CO3-. This labeling reflects the activities of phosphoenolpyruvate carboxylase and malate dehydrogenase (production of [4-13C]malate), and fumarase (scrambling of 13C-label between C1 and C4 of malate). In vivo 13C-NMR spectra contained a clearly resolved resonance from cytoplasmic [4-13C]malate, while the resonance from cytoplasmic [1-13C]malate overlapped with others. After 90 min of H13CO3- treatment, 13C-labeling of organic acid pools had reached steady-state. Thereafter, the ratios [13C]malate/[12C + 13C]malate and [1-13C]malate/[4-13C]malate in tissue extracts remained constant; evidence is presented that these ratios were the same for both cytoplasmic and total cellular malate. Hence, the intensity of the cytoplasmic [4-13C]malate signal was proportional to the amount of cytoplasmic malate in root tips. Potassium sulfate stimulate malate synthesis in maize root tips, relative to root tips perfused with HCO3- alone; total cellular malate doubled after approx. 1 h of 5 mM K2SO4-treatment. Cytoplasmic malate increased from approx. 3.5 mM to approx. 7.5 mM within 45 min of the onset of K2SO4-treatment, declining slightly thereafter. The possible effects of these changing cytoplasmic malate concentration on the enzymes involved in malate metabolism are discussed.
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PMID:Cytoplasmic malate levels in maize root tips during K+ ion uptake determined by 13C-NMR spectroscopy. 200 9

The CO2 adducts resulting from N-, O-, and S-carboxylation of suitable precursors are close analogues of carboxylate substrates in which -NH-CO2-, -O-CO2-, or -S-CO2- replaces -CH2-CO2- in the physiological substrate, -NOH-CO-2 replaces -CHOH-CO-2 and O-CO2- replaces -O-PO3H- R-XH + CO2 in equilibrium with R-X-CO2- + H+ X(-XH = -NH2, -NHOH, -OH or -SH). We find that aconitase catalyzes the CO2-dependent dehydration of N-hydroxy-DL-aspartate and erythro-beta-hydroxyl-L-aspartate with respective kcat values 62 and 90% of kcat for citrate and Km values of 3.6 and 3.2 mM, respectively. The CO2 adducts (carbamates) of the precursors would be structural and stereo analogues of the physiological substrate isocitrate. Detailed kinetic analyses of the behavior of intermediates and products show that aconitase catalyzes the formation of the enzyme-bound CO2 adducts from enzyme-bound precursors and CO2 and directs them, as well as the preformed CO2 adducts, into alpha,beta water elimination reactions formally identical to the isocitrate/cis-aconitate reaction. Six other enzymes of carbohydrate metabolism (succinate thiokinase and isocitrate, glucose-6-phosphate, succinate semialdehyde, glutamate, and malate dehydrogenase) utilize CO2 adducts as reactive substrate analogues. At least one of these (glucose-6-phosphate dehydrogenase) catalyzes the formation of the enzyme-bound CO2 adduct (presumed to be D-glucose 6-carbonate in this case) from enzyme-bound precursor (D-glucose) and CO2 in the manner of aconitase. The case of malate dehydrogenase is unique because the reactive malate analogue, -O2C-O-CHOH-CO-2, arises from nucleophilic attack of HCO-3 on the carbonyl of glyoxylate, rather than electrophilic attack of CO2 on the hydrated carbonyl of glyoxylate.
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PMID:CO2 adducts as reactive analogues of carboxylate substrates for aconitase and other enzymes of carbohydrate metabolism. 310 57

Mitochondria isolated from spinach leaves oxidized malate by both a NAD+-linked malic enzyme and malate dehydrogenase. In the presence of sodium arsenite the accumuation of oxaloacetate and pyruvate during malate oxidation was strongly dependent on the malate concentration, the pH in the reaction medium and the metabolic state condition. Bicarbonate, especially at alkaline pH, inhibited the decarboxylation of malate by the NAD+-linked malic enzyme in vitro and in vivo. Analysis of the reaction products showed that with 15 mM bicarbonate, spinach leaf mitochondria excreted almost exclusively oxaloacetate. The inhibition by oxaloacetate of malate oxidation by spinach leaf mitochondria was strongly dependent on malate concentration, the pH in the reaction medium and on the metabolic state condition. The data were interpreted as indicating that: (a) the concentration of oxaloacetate on both sides of the inner mitochondrial membrane governed the efflux and influx of oxaloacetate; (b) the NAD+/NADH ratio played an important role in regulating malate oxidation in plant mitochondria; (c) both enzymes (malate dehydrogenase and NAD+-linked malic enzyme) were competing at the level of the pyridine nucleotide pool, and (d) the NAD+-linked malic enzyme provided NADH for the reversal of the reaction catalyzed by the malate dehydrogenase.
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PMID:Effect of bicarbonate and oxaloacetate on malate oxidation by spinach leaf mitochondria. 735 82


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