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1.
Prolonged consumption of ethanol enhances the activities of the hepatic microsomal ethanol oxidizing system and of reduced nicotinamide-adenine dinucleotide phosphate oxidase, but not of catalase. The oxidase-catalase system is not part of the microsomal ethanol oxidizing system since catalase inhibitors dissociate ethanol oxidation by the two pathways. Enhanced reduced nicotinamide-adenine dinucleotide phosphate oxidase activity may contribute to liver injury, possibly by favoring lipoperoxidation.  相似文献   

2.
Neuroblastoma tumors, as well as cultured cells of neuroblastoma, contain high monoamine oxidase activity. The major deaminated metabolite of tyramine-H(3) in the incubation mixtures with the tumors or with the cultured cells is p-hydroxyphenylacetaldehyde. Upon addition of reduced nicotinamide-adenine dinucleotide phosphate, the aldehyde was further metabolized by the reductive pathway to p-hydroxyphenylethanol, whereas upon addition of nicotinamide-adenine dinucleotide phosphate the aldehyde was only metabolized to a minor extent by the oxidative pathway to p-hydroxyphenylacetic acid. Aldehyde dehydrogenase activity is very low in the neuroblastoma tumors and in the cultured neuroblastoma cells. The generation of aldehydes and alcohols by the action of monoamine oxidase suggests that the deaminated metabolites of biogenic amines might exhibit some toxic effects in neuroblastoma patients.  相似文献   

3.
The addition of glucose stimulated release of insulin from the isolated islet tissue of the toadfish incubated in vitro. Reduced nicotinamide-adenine dinucleotide also stimulated insulin release, whereas the oxidized form had no effect. Both oxidized and reduced nicotinamide-adenine dinucleatide phosphate stimulated insulin release, but the reduced form was significantly more effective.  相似文献   

4.
Microbial communities can subsist at depth in marine sediments without fresh supply of organic matter for millions of years. At threshold sedimentation rates of 1 millimeter per 1000 years, the low rates of microbial community metabolism in the North Pacific Gyre allow sediments to remain oxygenated tens of meters below the sea floor. We found that the oxygen respiration rates dropped from 10 micromoles of O(2) liter(-1) year(-1) near the sediment-water interface to 0.001 micromoles of O(2) liter(-1) year(-1) at 30-meter depth within 86 million-year-old sediment. The cell-specific respiration rate decreased with depth but stabilized at around 10(-3) femtomoles of O(2) cell(-1) day(-1) 10 meters below the seafloor. This result indicated that the community size is controlled by the rate of carbon oxidation and thereby by the low available energy flux.  相似文献   

5.
Hexokinase isoenzymes in human erythrocytes   总被引：4，自引：0，他引：4  
The electrophoretic mobility of hexokinase from human erythrocytes and other tissues was studied with a new method that depends on the fluorescence of reduced nicotinamide-adenine dinucleotide phosphate for detecting enzyme activity on starch gel. The hexokinase of cord-blood erythrocytes has slightly different electrophoretic properties from that of adult red cells. Type I enzyme is split into type I(A) and type I(F); the latter is more intense in cord blood; in hemolyzates of adult blood, the activity of the two bands is usually about equal. No type II enzyme was found in cord blood. The double type I band was present in red cells from adult rabbits.  相似文献   

6.
Reduced nicotinamide-adenine dinucleotide oxidase of normal human polymorphonuclear leukocytes has properties that would qualify it as the enzyme responsible for the respiratory burst during phagocytosis. The enzyme was deficient in leukocytes of five patients with chronic granulomatous disease. This lack of adequate reduced nicotinamide-adenine dinucleotide oxidase could be the basis for the metabolic abnormalities characteristic of these leukocytes and for their diminished bactericidal activity.  相似文献   

7.
Irradiation of the electron transport particles of Mycobacterium phlei with light at a wavelength of 360 manometers resulted in a loss of oxidase activities of succinate and the reduced form of nicotinamide adenine dinucleotide. The lesion in the two pathways caused by irradiation of the particles differs. The succinoxidase pathway was more labile to irradiation than the pathway linked to nicotinamide adenine dinucleotide. Restoration of succinoxidase activity (up to 50 to 60 percent) occurred on addition of a thermostable, water-soluble material obtained from Mycobacterium phlei cells or with an extract of mitochondria from boiled rat liver. Other known cofactors, such as flavine adenine dinucleotide, flavine mononucleotide, benzo- and naphthoquinones, as well as sulfhydryl agents, failed to restore succinoxidase activity after irradiation. Water-soluble material from Mycobacterium phlei appears to function between the flavoprotein and cytochrome b on the succinoxidase pathway. In contrast to the requirements for restoration of the pathway linked to nicotinamide adenine dinucleotide, restoration of succinoxidase does not occur with quinones or other cofactors such as flavine adenine dinucleotide.  相似文献   

8.
Alcohol dehydrogenase of Drosophila: interconversion of isoenzymes   总被引：7，自引：0，他引：7  
Isoenzymes of alcohol dehydrogenase extracted from Drosophila melanogaster are interconvertible and can be distinguished by electrophoretic mobility. When adsorbed on diethylaminoethyl cellulose, the faster-moving forms are converted to the slowest-moving form; the latter is converted to the former in the presence of 0.05 molar nicotinamide-adenine dinucleotide, and the conversion is accompanied by the binding of 3.5 moles of the dinucleotide per mole of enzyme. A change in heat stability accompanies the conversion of the slowest form of alcohol dehydrogenase to the fastest form; the latter becomes stable at 45 degrees C. The increased heat stability may indicate that a conformational change in the alcohol dehydrogenase occurs along with the binding of nicotinamide-adenine dinucleotide.  相似文献   

9.
A drug-induced stimulation of heme biosynthesis in mouse liver was accompanied by altered fumarate metabolism. In liver homogenate, fumarate 1,4-C(14) was incorporated, via succinate and succinyl coenzyme A, into heme at an accelerated rate. This pathway of fumarate utilization was inhibited by acetoacetate but not by beta-hydroxybutyrate. Fumarate reduction to succinate required reduced nicotinamide adenine dinucleotide. The enzyme fumarate reductase is suggested as a link between terminal oxidation and cellular control of the heme biosynthetic pathway.  相似文献   

10.
Hydroxylation of rotenone in vitro in the enzyme system composed of microsomes and reduced nicotinamide-adenine dinucleotide phosphate, and in living mice and houseflies, yields products tentatively identified as rotenolone I; rotenolone II; 8'-hydroxyrotenone; 6',7'-dihydro-6',7'-dihydroxyrotenone; two rotenolones of each of the last-mentioned two compounds; and uncharacterized polar materials. The toxicity of certain of these rotenoids to mice is of the same order as that of rotenone.  相似文献   

11.
Pyrazole and induction of fatty liver by a single dose of ethanol   总被引：2，自引：0，他引：2  
Pyrazole (4 millimoles per kilogram or 272 milligrams per kilogram of body weight), given to fasted rats 10 minutes before gavage with ethanol (4 grams per kilogram), completely prevented both the disappearance of ethanol from the blood over a 16-hour period and the ethanol-induced reduction in the ratio of oxidized to reduced hepatic nicotinamide-adenine dinucleotide. However, it did not affect the accumulation of triglycerides in the liver after the administration of ethanol. These results indicate that metabolism of ethanol is not required for production of fatty liver by a single, large dose of ethanol.  相似文献   

12.
Samples of blood (hemolyzed) were obtained from the renal vein, the hepatic portal vein, and the heart of a freshly thawed specimen of Latimeria chalumnae. The coelacanth uses high concentrations of urea to maintain its serum osmolality at approximately that of sea water. The mean value for the total osmolality was 1181 milliosmoles per liter. The mean values (milliequivalents per liter) were: for sodium, 181; for potassium, 51.3; for calcium, 6.9; for magnesium, 28.7; for chloride, 199; and for bicarbonate, 4.7. The mean urea concentration was 355 millimoles per liter, and the mean nonprotein nitrogen was 1343 milligrams percent. Heart blood showed significantly lower values for osmolality (921 milliosmoles per liter) and nonprotein nitrogen (1030 mg percent) and was probably less severely contaminated with products of protein breakdown. Fluid from the anterior chamber of the eye showed values of 952 milliosmole/liter; the urea value for this fluid was 303 mmole/liter, and the magnesium was 7.3 meq/liter. The magnesium value for the aqueous humor was used to correct the abnormally high concentrations in the hemolyzed serum. The high level of serum potassium also was attributed to hemolysis.  相似文献   

13.
The methylene-C(14) group is hydroxylated yielding formate-C(14) in the microsome-reduced nicotinamide-adenine dinucleotide phosphate system in vitro and yielding expired C(14)O(2), in living mice and houseflies. Methylenedioxyphenyl compounds apparently serve as alternate substrates for this enzymatic hydroxylation system of microsomes, and thus reduce the rate of metabolism and prolong the action of certain drugs and insecticide chemicals.  相似文献   

14.
Previous studies have suggested that hydroxymethanesulfonate ion (HMSA) can be an important species in fog and cloud water. Formation of HMSA explains observed excesses of sulfur in the S(IV) state (+4 oxidation state) and formaldehyde (CH(2)O) in fogs and clouds. HMSA was determined in fog water by a novel ion-pairing chromatographic technique. Concentrations in samples collected in Bakersfield, California, within 5 kilometers of major sources of sulfur dioxide (SO(2)), were as high as 300 micromoles per liter. Total CH(2)O and S(IV) concentrations, which were measured independently, ranged from 10 to 200 and 5 to more than 300 micromoles per liter, respectively. Concentrations of CH(2)O, S(IV), and HMSA at Buttonwillow, California, which is 15 kilometers from the nearest source of SO(2), were less than those at Bakersfield but not absent. These data confirm that HMSA forms in atmospheric water droplets and can reach appreciable concentrations. HMSA represents an important source of acidity for water droplets and may also play a role in long-distance transport and transformation of SO(2).  相似文献   

15.
The polymerization of allylamine in a radio-frequency electrodeless plasma to form thin polymer films on microporous filter media provides very effective dry composite membranes for reverse osmosis. Salt and urea rejections as high as 98 percent and 46 percent, respectively, have been achieved from a solution containing 10 grams of sodium chloride per liter and 10 grams of urea per liter. The plasma conditions and polymerization technique are discussed.  相似文献   

16.
D(-)-lactate dehydrogenase in lower fungi   总被引：1，自引：0，他引：1  
A lactate dehydrogenase, specific for nicotinamide-adenine dinucleotide and D(-)-lactate, has been detected in extracts from two fungi of the order Leptomitales (Oomycetes). Several fungi of this order carry out a lactic acid fermentation under conditions of reduced oxygen tension.  相似文献   

17.
In 1979 two areas of upwelling were observed off Somalia, one near 10 degrees N and one near 5 degrees N. The areas of upwelling were characterized by sea surface temperatures between 17 degrees and 22 degrees C, high concentrations of surface nutrients (5 to 20 micromoles of nitrate per liter) and surface chlorophyll a (0.4 to 5.0 milligrams per cubic meter), primary productivity averaging 1.7 grams of carbon per square meter per day, and a phytoplankton assemblage dominated numerically by the diatom Nitzschia delicatissima.  相似文献   

18.
Nicotinamide-adenine dinucleotide in tubercle bacilli exposed to isoniazid   总被引：3，自引：0，他引：3  
There is a decrease in the content of nicotinamide-adenine dinucleotide of tubercle bacilli grown in the presence of isoniazid. In extracts of tubercle bacilli, the activity of nicotinamide-adenine dinucleotidase is nil or very small; after incubation with the drug the enzyme becomes active. Isoniazid also increases the activity of the enzyme after it is partially activated by heating. There may be a correlation between the capacity of isoniazid to activate the enzyme and the decrease in the dinucleotide content of the tubercle bacilli.  相似文献   

19.
In thioredoxin reductase (TrxR) from Escherichia coli, cycles of reduction and reoxidation of the flavin adenine dinucleotide (FAD) cofactor depend on rate-limiting rearrangements of the FAD and NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) domains. We describe the structure of the flavin-reducing conformation of E. coli TrxR at a resolution of 3.0 angstroms. The orientation of the two domains permits reduction of FAD by NADPH and oxidation of the enzyme dithiol by the protein substrate, thioredoxin. The alternate conformation, described by Kuriyan and co-workers, permits internal transfer of reducing equivalents from reduced FAD to the active-site disulfide. Comparison of these structures demonstrates that switching between the two conformations involves a "ball-and-socket" motion in which the pyridine nucleotide-binding domain rotates by 67 degrees.  相似文献   

20.
A homogeneous system for the selective, catalytic oxidation of methane to methanol via methyl bisulfate is reported. The net reaction catalyzed by mercuric ions, Hg(II), is the oxidation of methane by concentrated sulfuric acid to produce methyl bisulfate, water, and sulfur dioxide. The reaction is efficient. At a methane conversion of 50 percent, 85 percent selectivity to methyl bisulfate ( approximately 43 percent yield; the major side product is carbon dioxide) was achieved at a molar productivity of 10(-7) mole per cubic centimeter per second and Hg(II) turnover frequency of 10(-3) per second. Separate hydrolysis of methyl bisulfate and reoxidation of the sulfur dioxide with air provides a potentially practical scheme for the oxidation of methane to methanol with molecular oxygen. The primary steps of the Hg(II)-catalyzed reaction were individually examined and the essential elements of the mechanism were identified. The Hg(II) ion reacts with methane by an electrophilic displacement mechanism to produce an observable species, CH(3)HgOSO(3)H, 1. Under the reaction conditions, 1 readily decomposes to CH(3)OSO(3)H and the reduced mercurous species, Hg(2)(2+) The catalytic cycle is completed by the reoxidation of Hg(2)(2+) with H(2)SO(4) to regenerate Hg(II) and byproducts SO(2) and H(2)O. Thallium(III), palladium(II), and the cations of platinum and gold also oxidize methane to methyl bisulfate in sulfuric acid.  相似文献   

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