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Query: UMLS:C0027960 (mole)
 21,279 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

15-Hydroxyprostaglandin dehydrogenase was isolated from human term placenta up to a final purification of 380-fold. A spec. act. of 2000 mU/mg of protein was reached. The preparation was not homogeneous as judged by analytical disc electrophoresis. The enzyme could be stored in the presence of 50% glycerol and 10mM 2-mercaptoethanol without any loss of activity for at least one year. A distinct single protein band stained after discontinuous polyacrylamide gel electrophoresis was shown by enzymatic activity staining to correspond to 15-hydroxyprostaglandin dehydrogenase activity. Thus no evidence for the exitstence of isoenzymes was obtained. The protein in the final preparation steps showed neither alcohol dehydrogenase, NAD reductase, nor NADH oxidase activity, nor enzymatic conversion of prostaglandin or 15-oxoprostaglandin in the absence of NAD and NADH. No spontaneous reactions between NAD and prostaglandin or NADH and 15-oxoprostaglandin were detectable in the absence of the enzyme. Ethanol and glycerol slightly inhibited the reaction. Various buffers (Tris/HC1, potassium phosphate, HEPES, and triethanolamine) and salts (ammonium chloride, ammonium sulfate, potassium chloride, and sodium chloride) had different effects on the reaction rate. The pH profile of the reaction shows a plateau between pH 7.0 and 7.8 and a steep maximum at pH 9.5. A linear Arrhenius plot was obtained for the temperature dependence of the reaction from 20 to 37 degrees C. The molar activation enthalpy of the reaction was calculated to be 13.1 kcal/mole. The molecular weight of 15-hydroxyprostaglandin dehydrogenase was estimated to be 32000 -/+ 3000 by gel filtration on Sephadex G-150 in the presence of 10mM mercaptoethanol.
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PMID:[15-Hydroxyprostaglandin dehydrogenase from human placenta. 1. Isolation and characterization]. 24 91

The effect of ethanol on hepatic respiration and glycolysis was studied in perfused rat livers. 1. Ethanol increased the rate of oxygen uptake in livers from fed rats, but decreased the rate in livers from fasted animals perfused in the absence of added substrates. 2. Addition of ethanol decreased the rate of lactate + pyruvate production reflecting an inhibition of glycolysis irrespective of whether glycogen or added glucose was the substrate. 3. Half-maximal stimulation of respiration and inhibition of glycolysis were observed at ethanol concentrations between 0.2 and 0.4 mM. 4. A stoichiometric relationship of one mole of stimulated oxygen uptake to 3.6 mol of decreased lactate + pyruvate production was observed under a variety of experimental conditions. 5. The effects of ethanol on oxygen uptake and lactate + pyruvate production were abolished by the addition of 4-methylpyrazole, an inhibitor of alcohol dehydrogenase, but were unaffected by aminooxyacetate, an inhibitor of hydrogen transport across the mitochondrial membrane. 6. Carboxyatractyloside, an inhibitor of adenine nucleotide translocase, largely abolished the increase in oxygen uptake due to ethnol, but had little effect on the inhibitory action of ethanol on glycolysis. These data indicate that the ethanol-stimulated oxygen uptake is due to an increased flux through the mitochondrial respiratory chain and that it involves the NAD+-dependent oxidation of ethanol by alcohol dehydrogenase. The data are consistent with the hypothesis that the ethanol-stimulated respiration results from an increased demand for mitochondrial oxidative phosphorylation as a consequence of the decreased extramitochondrial ATP generation following inhibition of glycolysis by ethanol.
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PMID:Interaction of glycolysis and respiration in perfused rat liver. Changes in oxygen uptake following the addition of ethanol. 86 14

The partitioning of ethanol into mouse brain synaptosomes at 37 degrees C was characterized as a function of ethanol concentration. In addition, the partitioning of ethanol into multilamellar dipalmitoylphosphatidylcholine (DPPC) vesicles was characterized as a function of ethanol concentration and temperature. DPPC liposomes provided a model for ethanol partitioning into a phospholipid bilayer of defined composition allowing comparison to the more complex synaptosomal membrane. The values of the partition coefficients for ethanol depend on the convention used to express concentration in the partition coefficient ratio. We express these concentrations as mole fractions as ethanol in the membrane and aqueous phases. Ethanol partitioning is nonideal (ethanol membrane: buffer partition coefficients vary with total ethanol concentration). In synaptosomes, the partition coefficients vary markedly with concentration and asymptotically approach zero at higher concentrations. In the DPPC system, the variation of the partition coefficient is less pronounced, but significant. The ethanol: DPPC partition coefficients decrease by a factor of 2 at ethanol concentrations above 3.2 x 10(-3) M. This suggests a model involving at least two distinguishable types of interactions of ethanol with the membrane. Ethanol appears to undergo both bulk phase partitioning into the membrane bilayer core and nonspecific binding to the membrane surface. In pure DPPC, bulk phase hydrophobic partitioning predominates. In synaptosomes, nonspecific surface binding appears to be a major interaction. Temperature studies indicate ethanol partitioning into DPPC increases above the phospholipid gel to liquid crystalline phase transition temperature. This suggests a preferred partitioning of ethanol into fluid state lipid. However, significant membrane concentrations of ethanol are found in gel state DPPC.
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PMID:A comparison of ethanol partitioning in biological and model membranes: nonideal partitioning is enhanced in synaptosomal membranes. 268 71

The specific effect of ethanol on several aspects of the gel-to-liquid crystal transition of dipalmitoylphosphatidylcholine was investigated using two spectrophotometric techniques, one probe method and one direct method. Ethanol shifts the phase-transition temperature to low temperature, demonstrating that ethanol interacts preferentially with the fluid phase. Thermodynamic analysis of the melting point depression leads to a calculated membrane:buffer partition coefficient of 6.25 (mole fraction units) or 0.15 mole of ethanol per kilogram of lipid:mole of ethanol per liter of solution. Careful evaluation of the transition cooperativity with temperature resolution of +/- 0.1 degrees shows that there is no reduction in transition cooperativity, and thus no reduction in size of the cooperative lipid clusters due to ethanol. The implications of these findings for the mechanism of action of ethanol in terms of current theories of anesthetic mechanisms are discussed.
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PMID:The effects of ethanol on the thermotropic properties of dipalmitoylphosphatidylcholine. 689 3

The transbilayer distribution of phosphatidylethanolamine was assessed in phosphatidylcholine-phosphatidylethanolamine vesicles that contained various amounts of cytochrome b5. The small vesicles, made by sonication, and the large vesicles, made by ethanol injection, were fractionated by centrifugation before cytochrome b5 was asymmetrically incorporated into the bilayer. The mole ratio of phospholipid to protein ranged from 280 to 560 in the small vesicles and from 100 to 500 in the large vesicles. The phosphatidylethanolamine distribution, determined by chemical labeling with trinitrobenzenesulfonic acid, was assessed in vesicles the contained intact cytochrome b5 molecules and in vesicles where only the hydrophobic tail remained associated with the bilayer. At every phospholipid to protein ratio examined, the transbilayer distribution of phosphatidylethanolamine in either the small or large unilamellar vesicles was not significantly different from the distribution in control vesicles that contained no protein. Ethanol was added to some cytochrome b5-vesicle preparations (20% v/v) in an attempt to facilitate rearrangement of the phospholipids. No differences in the transbilayer distribution were observed. These results are discussed in terms of transbilayer equilibrium and the perturbation induced by the protein.
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PMID:Effect of cytochrome b5 on the transbilayer distribution of phospholipids in model membranes. 710 93

The aim of this study is to develop a model predictive controller (MPC) accompanied with a metabolic reaction model controller for controlling ethanol and n-pentanol concentrations and the mole fraction of monomer units in the production of poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate), P(HB-co-HV), a biodegradable copolyester. The controller consists of two parts: one is for alcohol concentration control and the other one is for mole fraction control, and is based on the concept of metabolic flux distribution control. For control of alcohol concentration, conventional proportional and integral (PI) controller and feedforward/feedback controller did not function sufficiently because the large sampling interval of the biosensor led to a severe overshoot of concentration. A single-input and single-output (SISO) MPC is constructed for control of ethanol concentration in the growth phase, whereas a multi-input and multi-output (MIMO) MPC is constructed for control of both alcohol concentrations in the production phase. Specific ethanol consumption rate was estimated by the MPC using the past time series data of ethanol concentration. By means of simulations and experiments, the weighting parameters of the noise filters in the MPC were well adjusted. Ethanol and n-pentanol concentrations were well controlled by the MPC, compared with PI controller and feedforward/feedback controller. As a result, P(HB-co-HV) production was maximized with a given value of mole fraction of 3HV units at the end of cultivation.
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PMID:Model predictive controller for biodegradable polyhydroxyalkanoate production in fed-batch culture. 1191 25

The influence of the oxygen supply on the growth, acetic acid and ethanol production by Brettanomyces bruxellensis in a glucose medium was investigated with different air flow rates in the range 0-300 l h(-1 ) x (0-0.5 vvm). This study shows that growth of this yeast is stimulated by moderate aeration. The optimal oxygen supply for cellular synthesis was an oxygen transfer rate (OTR) of 43 mg O(2) l(-1) x h(-1). In this case, there was an air flow rate of 60 l h(-1) (0.1 vvm). Above this value, the maximum biomass concentration decreased. Ethanol and acetic acid production was also dependent on the level of aeration: the higher the oxygen supply, the greater the acetic acid production and the lower the ethanol production. At the highest aeration rates, we observed a strong inhibition of the ethanol yield. Over 180 l h(-1) x (0.3 vvm, OTR =105 mg O(2) l(-1) x h(-1)), glucose consumption was inhibited and a high concentration of acetic acid (6.0 g x l(-1)) was produced. The ratio of "ethanol + acetic acid" produced per mole of consumed glucose using carbon balance calculations was analyzed. It was shown that this ratio remained constant in all cases. This makes it possible to establish a stoichiometric equation between oxygen supply and metabolite production.
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PMID:Brettanomyces bruxellensis: effect of oxygen on growth and acetic acid production. 1265 58

Epidemiological studies have shown that moderate intake of red wine reduces the risk of coronary heart disease. It has been proposed that the antiatherogenic effect be due to the scavenging of reactive oxygen species by polyphenols and ethanol or an effect on endothelial nitric oxide (NO) production. We have determined the reaction rates of superoxide with four different polyphenols and ethanol. The superoxide reaction rates were determined at 37 degrees C and pH 7.4 using competitive spin trapping and electron paramagnetic resonance (EPR) spectroscopy. Ethanol did not scavenge superoxide. For the polyphenols catechin, epicatechin, gallic acid, and quercetin, we find rate constants of respectively 2.3*10(4), 2.2*10(4), 2.3*10(3) and 1.9*10(4)(mole per second)(-1). Polyphenols can only exert a significant scavenging effect, if the plasma concentration reach sufficiently high levels. At concentrations found in vivo (low nanomolar range), the scavenging of superoxide by polyphenols and ethanol is negligible in comparison with endogenous protection against superoxide. Incubation of cultured endothelial cells with 5 micromol/L of catechin, epicatechin, gallic acid, quercetin, or ethanol 0.05% (v/v) did not influence the maximal production of NO by these cells as measured by fluorescent nitric oxide cheletropic traps (FNOCT). The observed antiatherogenic effects must be caused by a mechanism other than direct scavenging of superoxide or influence on maximal endothelial NO production.
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PMID:Wine polyphenols and ethanol do not significantly scavenge superoxide nor affect endothelial nitric oxide production. 1521 28

The effects of temperature, solvents, and cultural conditions on the fermentative physiology of an ethanol-tolerant (56 g/liter at 60 degrees C) and parent strain of Clostridium thermohydrosulfuricum were compared. An ethanol-tolerant mutant was selected by successive transfer of the parent strain into media with progressively higher ethanol concentrations. Physiological differences noted in the mutant included enhanced growth, tolerance to various solvents, and alterations in the substrate range and the fermentation end product ratio. Ethanol tolerance was temperature dependent in the mutant but not in the parent strain. The mutant grew with ethanol concentrations up to 8.0% (wt/vol) at 45 degrees C, but only up to 3.3% (wt/vol) at 68 degrees C. Low ethanol concentration (0.2 to 1.6% [wt/vol]) progressively inhibited the parent strain to where glucose was not fermented at 2.0% (wt/vol) ethanol. Both strains grew and produced alcohols on glucose complex medium at 60 degrees C in the presence of either 5% methanol or acetone, and these solvents when added at low concentration stimulated fermentative metabolism. The mutant produced ethanol at high concentrations and displayed an ethanol/glucose ratio (mole/mole) of 1.0 in media where initial ethanol concentrations were </=4.0% (wt/vol), whereas when ethanol concentration was changed from 0.1% to 1.6% (wt/vol), the ethanol/glucose ratio for the parent strain changed from 1.6 to 0.6. These data indicate that C. thermohydrosulfuricum strains are tolerant of solvents and that low ethanol tolerance is not a result of disruption of membrane fluidity or glycolytic enzyme activity.
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PMID:Ethanol Production by Thermophilic Bacteria: Physiological Comparison of Solvent Effects on Parent and Alcohol-Tolerant Strains of Clostridium thermohydrosulfuricum. 1634 85

The anaerobic starch breakdown into end-products in the green alga Chlamydomonas reinhardtii F-60 has been investigated in the dark and in the light. The effects of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) and carbonyl cyanide-p-trifluoromethoxyphenyl hydrazone (FCCP) on the fermentation in the light have also been investigated.Anaerobic starch breakdown rate (13.1 +/- 3.5 micromoles C per milligram chlorophyll per hour) is increased 2-fold by FCCP in the dark. Light (100 watts per square meter) decreases up to 4-fold the dark rate, an inhibition reversed by FCCP. Stimulation of starch breakdown by the proton ionophore FCCP points to a pH-controlled rate-limiting step in the dark, while inhibition by light, and its reversal by FCCP, indicates a control by energy charge in the light.In the dark, formate, acetate, and ethanol are formed in the ratios of 2.07:1.07:0.91, and account for roughly 100% of the C from the starch. H(2) production is 0.43 mole per mole glucose in the starch. Glycerol, d-lactate, and CO(2) have been detected in minor amounts.In the light, with DCMU and FCCP present, acetate is produced in a 1:1 ratio to formate, and H(2) evolution is 2.13 moles per mole glucose. When FCCP only is present, acetate production is lower, and CO(2) and H(2) evolution is 1.60 and 4.73 moles per mole glucose, respectively.When DCMU alone is present, CO(2) and H(2) photoevolution is higher than in the dark. Without DCMU, CO(2) and H(2) evolution is about 100% higher than in its presence. In both conditions, acetate is not formed. In all conditions in the light, ethanol is a minor product. Formate production is least affected by light.The stoichiometry in the dark indicates that starch is degraded via the glycolytic pathway, and pyruvate is broken down into acetyl-CoA and formate. Acetyl-CoA is further dissimilated into acetate and ethanol. In the light, acetate is produced only in the presence of FCCP and, when photophosphorylation is possible, it is used in unidentified reactions. Ethanol formation is inhibited by the light in all conditions.
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PMID:Fermentative Metabolism of Chlamydomonas reinhardtii: I. Analysis of Fermentative Products from Starch in Dark and Light. 1666 74


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