Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: CAS:7440-44-0 (Carbon)
 10,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Glutamine was found to be the main carbon and nitrogen product of the metabolism of aspartate in isolated guinea-pig kidney-cortex tubules. Glutamate, ammonia and alanine were only minor products. 2. Carbon-balance calculations and the release of 14CO2 from [U-14C]aspartate indicate that oxidation of the aspartate carbon skeleton occurred. 3. A pathway involving aspartate aminotransferase, glutamate dehydrogenase, glutamine synthetase, phosphoenolpyruvate carboxykinase, pyruvate kinase, pyruvate dehydrogenase and enzymes of the tricarboxylic acid cycle is proposed for the conversion of aspartate into glutamine. 4. Evidence for this pathway was obtained by: (i) inhibiting aspartate removal by amino-oxyacetate, an inhibitor of transaminases, (ii) the use of methionine sulphoximine, an inhibitor of glutamine synthetase, which induced a large increase in ammonia release from aspartate, (iii) the use of quinolinate, an inhibitor of phosphoenolpyruvate carboxykinase, which inhibited glutamine synthesis from aspartate, (iv) the use of alpha-cyano-4-hydroxycinnamate, an inhibitor of the mitochondrial transport of pyruvate, which caused an accumulation of pyruvate from aspartate, and (v) the use of fluoroacetate, an inhibitor of aconitase, which inhibited glutamine synthesis with concomitant accumulation of citrate from aspartate.
 ...
PMID:Glutamine synthesis from aspartate in guinea-pig renal cortex. 236 82

Alveolar macrophages were treated with carbon blacks and adsorbates in order to evaluate the biologic effect of adsorbate, adsorbent and adsorbate-adsorbent complexes. Their capacity to phagocytize a subsequent challenge via the Fc-membrane receptor was quantified. Phagocytosis was suppressed in a dose-related manner with increasing concentrations of both carbon blacks and adsorbates. Carbon black N339 covered with 0.5 monolayers of the adsorbates suppressed phagocytosis more than N339 without the adsorbates. Increasing the adsorbate acrolein coverage from 0.5 to greater than 2.0 monolayers suppressed phagocytosis in a dose-related manner. Finally, samples of diesel particulate matter collected from an engine operated on a pure hydrocarbon fuel with various oxidizers, air (PSU #1) and an oxidizer free of nitrogen (N-free) were tested. Treatment of the macrophages with PSU #1 had a negligible effect on phagocytosis whereas the N-free sample suppressed phagocytosis in a dose-related manner. The data show that alveolar macrophage Fc-receptor-mediated phagocytosis is affected by: carbon black and adsorbate identity and concentration, coverage of the carbon black with adsorbates, and the oxidizer used in the generation of particles emitted by a diesel engine.
 ...
PMID:Suppression of alveolar macrophage membrane receptor-mediated phagocytosis by model and actual particle-adsorbate complexes. Initial contact with the alveolar macrophage membrane. 240 Dec 70

When used in concert, one-bond carbon-carbon correlations, one-bond and multiple-bond proton-carbon correlations, and multiple-bond proton-nitrogen correlations, derived from two-dimensional (2D) NMR spectra of isotopically enriched proteins, provide a reliable method of assigning proton, carbon, and nitrogen resonances. In contrast to procedures that simply extend proton assignments to carbon or nitrogen resonances, this technique assigns proton, carbon, and nitrogen resonances coordinately on the basis of their integrated coupling networks. Redundant spin coupling pathways provide ways of resolving overlaps frequently encountered in homonuclear 1H 2D NMR spectra and facilitate the elucidation of complex proton spin systems. Carbon-carbon and proton-carbon couplings can be used to bridge the aromatic and aliphatic parts of proton spin systems; this avoids possible ambiguities that may result from the use of nuclear Overhauser effects to assign aromatic amino acid signals. The technique is illustrated for Anabaena 7120 flavodoxin and cytochrome c-553, both uniformly enriched with carbon-13 (26%) or nitrogen-15 (98%).
 ...
PMID:Concerted two-dimensional NMR approaches to hydrogen-1, carbon-13, and nitrogen-15 resonance assignments in proteins. 253 56

Examination of the peroxidase isolated from the inkcap Basidiomycete Coprinus cinereus shows that the 42,000-dalton enzyme contains a protoheme IX prosthetic group. Reactivity assays and the electronic absorption spectra of native Coprinus peroxidase and several of its ligand complexes indicate that this enzyme has characteristics similar to those reported for horseradish peroxidase. In this paper, we characterize the H2O2-oxidized forms of Coprinus peroxidase compounds I, II, and III by electronic absorption and magnetic resonance spectroscopies. Electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) studies of this Coprinus peroxidase indicate the presence of high-spin Fe(III) in the native protein and a number of differences between the heme site of Coprinus peroxidase and horseradish peroxidase. Carbon-13 (of the ferrous CO adduct) and nitrogen-15 (of the cyanide complex) NMR studies together with proton NMR studies of the native and cyanide-complexed Coprinus peroxidase are consistent with coordination of a proximal histidine ligand. The EPR spectrum of the ferrous NO complex is also reported. Protein reconstitution with deuterated hemin has facilitated the assignment of the heme methyl resonances in the proton NMR spectrum.
 ...
PMID:Magnetic resonance spectral characterization of the heme active site of Coprinus cinereus peroxidase. 254 57

Positron emission tomography (PET) is a safe noninvasive visualization technique which gives an accurate and quantitative representation of the spatial distribution of a positron-emitting radionuclide in any desired transverse section of the body. Short-lived positron emitters such as Carbon-11 (half-life:20 min.). Nitrogen-13 (10 min), Fluorine-18 (110 min) or Bromine 75 can be incorporated into biological molecules:amino acids, sugars, fatty acids, hormones and receptor agonists or antagonists. The PET approach may be compared to quantitative autoradiography with the added advantage of allowing in vivo kinetic studies in man, under normal and pathological conditions. Regional myocardial perfusion is measured with rubidium-82, 13N-labelled ammonia, H2(15) O or albumin microspheres labelled with Gallium-68. Regional myocardial metabolism is assessed with 11C-palmitate and 18F-fluorodeoxyglucose. A high and spatially homogenous accumulation of 11C-palmitate is seen in normal myocardium. PET delineates an increased regional accumulation of 18F-2-FDG in ischemic areas while 11C-palmitate accumulation is markedly reduced. Positron Emission Tomography offers a unique opportunity to study receptors in vivo in normal and disease conditions. A potent muscarinic antagonist, 11C-MQNB is used to study the myocardial acetylcholine receptor and beta-blockers, 11C-Pindolol and 11C-CGP 12177 are used to study the beta-adrenergic receptor. The peripheral-type benzodiazepine receptor has been characterized with 11C-PK 11195.
 ...
PMID:In vivo investigation of myocardial perfusion, metabolism and receptors by positron emission tomography. 255 82

Carbon-13 nuclear magnetic resonance techniques were employed to examine the effects of solvent environment on rotational barriers in a series of molecules structurally-related to the analeptic, nikethamide: N,N-dimethylnicotinamide, N,N-di-n-propylnicotinamide, and 1-nicotinoyl piperidine. Total bandshape analysis was performed for the exchanging alkyl carbon resonances of these compounds as a function of temperature in four solvent systems: D2O, CH3OD, CH3CH2OD and CDCl3. The rate constants for rotation about the amide bond obtained in this way were used to calculate free energy (delta G), enthalpy (delta H) and entropy (delta S) of activation parameters for this process. Our results indicate that rotational barriers are less affected by the nature of the alkyl chain attached to the amide nitrogen than by the size and polarity of the solvent molecules. Interpretation of the thermodynamic parameters in light of both nikethamide analogue structure and solvent type has further clarified the manner in which hydrogen bonding interactions between solvent molecules and the carbonyl oxygen of these analogues stabilize transition state conformers.
 ...
PMID:Solvent interactions with N, N-dialkylnicotinamides and their effects on rotational barriers. 293 6

A model system has been used to study the types of radicals formed on denitrosation of N-nitroso compounds. Free radicals were formed at room temperature (22 degrees-23 degrees C) and neutral pH by photolytic cleavage of N-nitroso bonds and were partially characterized following their addition to the spin traps 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and N-tert-butyl-alpha-phenyl-nitrone (PBN). Carbon-centered radical adducts were obtained during nitrosamine photolysis and nitrogen-centered radical adducts during nitrosamide photolysis. Since both the nitrosamines and nitrosamides initially form nitrogen-centered radicals on photolysis, a secondary reaction or rearrangement must occur after initial N-nitroso bond cleavage in the nitrosamines. Mechanisms are proposed to account for these results.
 ...
PMID:Photolysis of nitrosamines and nitrosamides at neutral pH: a spin-trap study. 304 May 36

In an earlier paper (Ghose A. K.; Crippen, G. M. J. Comput. Chem. 1986, 7, 565) the need of atomic physicochemical properties for three-dimensional-structure-directed quantitative structure-activity relationships was demonstrated, and it was shown how atomic parameters can be developed to successfully evaluate the molecular water-1-octanol partition coefficient, which is a measure of hydrophobicity. In the present work the atomic values of molar refractivity are reported. Carbon, hydrogen, oxygen, nitrogen, sulfur, and halogens are divided into 110 atom types of which 93 atomic values are evaluated from 504 molecules by using a constrained least-squares technique. These values gave a standard deviation of 1.269 and a correlation coefficient of 0.994. The parameters were used to predict the molar refractivities of 78 compounds. The predicted values have a standard deviation of 1.614 and a correlation coefficient of 0.994. The degree of closeness of the linear relationship between the atomic water-1-octanol partition coefficients and molar refractivities has been checked by the correlation coefficient of 89 atom types used for both the properties. The correlation coefficient has been found to be 0.322. The low value suggests that both parameters can be used to model the intermolecular interaction. The origin of these physicochemical properties and the types of interaction that can be modeled by these properties have been critically analyzed.
 ...
PMID:Atomic physicochemical parameters for three-dimensional-structure-directed quantitative structure-activity relationships. 2. Modeling dispersive and hydrophobic interactions. 355 6

Measurements of Carbon Monoxide (CO) and Nitrogen Dioxide (NO2) were made in three kitchens, two with gas cookers and one all electric, and two living rooms, one heated by a portable butane heater and the other by a paraffin stove. The measurements were taken whilst the homes were in normal use and the occupants kept a diary of when specific appliances were used. Measurements of NO2 were made simultaneously by chemiluminescence and by diffusion tubes. The accuracy of the diffusion tube measurements relative to the chemiluminescent standard was estimated as +/- 10% and the precision less than or equal to 300 ppb. hr. Results from diffusion tubes were used to indicate the distribution of NO2 throughout other rooms in the house. At the all electric house the CO and NO2 concentrations were very similar to the expected outdoor levels. In all the other houses NO2 levels exceeded typical outdoor concentrations measured in Central London and in the paraffin heated house and one gas cooking house median CO concentrations exceeded these measured at the curbside of a very busy road in Central London. The living room concentrations of NO2 where the paraffin heater was in use were elevated for long periods. Analysis of the decay of pollutant concentration in one kitchen yielded an effective deposition velocity for NO2 of 3 X 10(-5) m s-1. The magnitude of the CO and NO2 concentrations measured in this survey confirms that indoor air pollution should be taken into account when assessing overall public exposure to air pollution.
 ...
PMID:Measurements of carbon monoxide and nitrogen dioxide in British homes using unflued heating or cooking appliances. 383 8

The phenomena of flocculation and floc formation by Azospirillum brasilense Sp7 (ATCC 29145) and Azospirillum lipoferum Sp59b (ATCC 29707) were studied in aerobic liquid cultures. Carbon sources representative of various entry pathways in combination with various nitrogen sources induced flocculation in both species of azospirilla. Noticeably, the combination of fructose and nitrate was the most effective in terms of floc yields. Phase-contrast microscopic observations revealed a transition in cell morphology from freely motile, vibrioid cells to nonmotile, highly refractile encysting forms during the formation of flocs. The nonmotile forms in flocs appeared to be entangled within a fibrillar matrix, and the cells were highly resistant to desiccation. Dried flocs kept for almost 6 months still maintained the highly refractile encysting forms, and their viability was confirmed by pellicle formation and acetylene reduction in semisolid malate medium. Electron microscopic observations of the desiccated flocs revealed the presence of cell forms containing abundant poly beta-hydroxybutyrate granules within a central body and surrounded by a thick layer of exopolysaccharides. The latter were characterized by alkali and acid digestion, crude cellulase hydrolysis, and calcofluor staining. It was concluded that the overproduction of exocellular polymers induces the flocculent growth and is associated with the concomitant transformation of vegetative cells to the desiccation-resistant encysting forms under limiting cultural conditions.
 ...
PMID:Flocculation in Azospirillum brasilense and Azospirillum lipoferum: exopolysaccharides and cyst formation. 389 33


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>