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Query: CAS:7440-44-0 (Carbon)
 10,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pyrimidine ribonucleoside catabolic enzyme activities of the opportunistic pathogen Pseudomonas pickettii were examined. Of the pyrimidine and related compounds tested, only dihydrouracil (nitrogen source) and ribose (carbon source) supported growth. Thin-layer chromatographic separation of the uridine and cytidine catabolities produced by P. pickettii extracts indicated that this pseudomonad contained nucleoside hydrolase activity. Its presence was confirmed by enzyme assay. Hydrolase activity was elevated in both glucose- and ribose-grown cells relative to succinate-grown cells. Nucleoside hydrolase activity was depressed when dihydrouracil served as a nitrogen source. Cytosine deaminase activity was present in extracts prepared from succinate-, glucose- or ribose-grown cells when (NH4)2SO4 served as the nitrogen source although cells grown on glucose or ribose exhibited a higher enzyme activity. Cytosine deaminase activity was not detected in extracts prepared from cells grown on dihydrouracil as a nitrogen source. Both dihydropyrimidine dehydrogenase and dihydropyrimidinase activities were measurable in P. pickettii. The dehydrogenase activity was higher with NADH than with NADPH as its nicotinamide cofactor when uracil served as its substrate. Carbon source did not affect dehydrogenase or dihydropyrimidinase activity greatly but both activities were diminished in cells grown on the nitrogen source dihydrouracil.
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PMID:Pyrimidine ribonucleoside catabolic enzyme activities of Pseudomonas pickettii. 771 Feb 77

Eight strains of Cryptococcus neoformans var. neoformans isolated from AIDS patients in the Infectious Disease Institute, University of Turin, Italy, were examined for growth and extracellular proteolytic activity in culture with solid and liquid media. All of the strains grew well on Yeast Carbon Base (YCB) agar medium supplemented with both 0.1% (w/v) bovine serum albumin (BSA) and 0.01% (w/v) polypeptone (Pp), and produced a clear proteolytic zone around their colonies, whereas they exhibited less growth and proteolytic activity on YCB medium supplemented with BSA alone. Strain #8 with a strong proteolytic activity was cultured in three different liquid media. Its growth was limited in YCB medium supplemented with 0.1% BSA, but was moderate in that with 0.01% Pp. Enhanced growth was supported by the addition of both BSA and Pp to the YCB medium. The relative value of the final cellular yields obtained with the above YCB-0.1% BSA, YCB-0.01% Pp and YCB-0.1% BSA-0.01% Pp media was approximately 1:10:20. In the culture with YCB medium containing both BSA and Pp, a rapid decrease in the amount of BSA was demonstrated by a spectrophotometric assay and gel electrophoresis of the culture supernatant after the log-to-stationary phase. The proteolytic activity in the culture supernatant became detectable after the log phase when tested with skim milk agarose plates. These results allowed us to conclude that Cr. neoformans var. neoformans is able to secrete protease and to utilize protein as a source of nitrogen.
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PMID:Extracellular proteolytic activity of Cryptococcus neoformans. 773 28

A two-dimensional (2D) experiment has been used to show that 14N irradiation and magic-angle spinning (MAS) results in population transfers between the 14N Zeeman levels. This experiment was applied to a sample of N-acetyl-D,L-valine, a material where asymmetric doublets resulting from 13C-14N dipolar coupling are clearly resolved in the 13C spectrum at a field of 7 T for Carbon atoms directly bonded to the nitrogen atom. The 13C transverse magnetization was allowed to evolve in the F1 and F2 dimensions, and the 14N spins were irradiated during the mixing period. Cross-peaks were observed in the 2D 13C spectrum between the two peaks of the CH asymmetric doublet. Since one peak of the doublet results primarily from coupling to the [formula: see text] state and the other peak from coupling to [formula: see text] states, population changes between the 14N Zeeman levels have occurred during the mixing period. These population transfers are a consequence of the time dependence of the 14N quadrupole splitting Q under MAS conditions and 14N irradiation. Level anti-crossings of the 14N Zeeman levels occur at the zero-crossings of Q, and a continuous and slow change in Q will result in the transfer of 14N populations between the different Zeeman levels. If these passages are adiabatic, then the system returns to its original state after two zero-crossings. This is consistent with the experimental observation that the intensities of the cross-peaks for 14N irradiation are greater for half a rotor period than a full rotor period.
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PMID:14N population transfers in two-dimensional 13C-14N-1H triple-resonance magic-angle spinning nuclear magnetic resonance spectroscopy. 776 60

The responses of Pseudomonas putida KT2442 to various forms of nutrient starvation and stress conditions were examined by two-dimensional polyacrylamide electrophoresis. Carbon deprivation resulted in a temporal expression of two classes of starvation-induced proteins: one class was transiently expressed during the initial phase of starvation, and the second class was expressed throughout the entire starvation period. Proteins of the second class could be further subdivided into proteins induced specifically under conditions of carbon starvation, proteins also induced by conditions of stress created by elevated temperature and osmolarity, and finally proteins that were also induced by conditions of nitrogen as well as phosphate starvation. Addition of glucose to a carbon-starved culture led to initiation of a recovery phase. During this phase, repression of starvation-induced proteins as well as induction of a new class of transiently expressed proteins, referred to as maturation proteins, took place.
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PMID:Responses to nutrient starvation in Pseudomonas putida KT2442: two-dimensional electrophoretic analysis of starvation- and stress-induced proteins. 805 Sep 94

The solid-state conformation of [Nle12]alpha-factor, the Saccharomyces cerevisiae tridecapeptide mating pheromone (WHWLQLKPGQPNleY), was investigated by 13C,15N rotational-echo double resonance (REDOR) nuclear magnetic resonance spectroscopy (NMR). Previous high-resolution NMR studies of [Nle12]alpha-factor in solution revealed a transient Type II beta-turn spanning residues 7-10 of the peptide. To investigate this region of [Nle12]alpha-factor in the solid state, a series of four selectively 13C,15N-enriched tridecapeptides were synthesized by solid-phase methods. Carbon-nitrogen distances between the labeled sites in lyophilized samples of [Nle12]alpha-factor were accurately measured by REDOR NMR. Experimentally determined distances were compared with those from calculated models for Type I and Type II beta-turns and for an extended chain. The measured distances indicate that, in a lyophilized powder, the central region of the [Nle12]alpha-factor is not in an extended conformation. The experimental data was most consistent with distances obtained from a distorted Type I beta-turn model.
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PMID:Conformational analysis of the Saccharomyces cerevisiae tridecapeptide mating pheromone by 13C,15N rotational-echo double resonance nuclear magnetic resonance spectroscopy. 806 Sep 78

Various low molecular weight substances cause occupational asthma, and there is scope for studying their chemical properties in relation to their propensity to cause this condition. Twenty-nine organic substances (molecular weight < 250), with or without oxygen or nitrogen atoms, were compared to control hazardous substances obtained from the list of occupational exposure limits. There were significantly more reactive groups in the active chemicals than in the controls. Carbon to nitrogen double bonds were also significantly over-represented in the active chemicals. If confirmed in a fuller study, these data could yield useful information on the causation of occupational asthma and on the hazard assessment of novel chemical entities.
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PMID:Occupational asthma and the chemical properties of low molecular weight organic substances. 816 17

Candida zeylanoides caused candidiasis as tinea cruris in 4 cases. Candida zeylanoides were characterized by good growth of the strain in malt medium, potato dextrose agar and Sabourard's agar. Their colony was milky white and greasy with smooth surface. The diameter of the colony reaches 12 mm within a week. As candida type pseudohyphae but not hyphae, they do not produce ascospore and bolospore. Carbon sources fermentation showed positive results. Nitrogen sources assimilation agar (KNO3) negative, arbutin agar negative, nonvitamin medium positive. G+C mol% value of their DNA was 51.24. Animal experiment showed that guinea pigs were infected by Candida zeylanoides. The main feature of candidiasis as tinea cruris caused by the strain was pink infiltrative erythema with clear margin, a lot of grain-sized papules, a few vesicles, and thin scales. The disease can be cured by preparation of ketoconazole.
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PMID:Candida zeylanoides causing candidiasis as tinea cruris. 824 28

Laser desorption time-of-flight mass spectra of peptides and proteins, as well as of lower molecular weight analytes, have been obtained by using a pulsed nitrogen UV laser (337 nm) to irradiate mixtures of 2-150 microns graphite particles and solutions of the analytes in glycerol. Protonated analytes as well as abundant alkali cation adducts were observed. Carbon cluster ions, Cn+, typically had a low abundance but dominated the mass spectrum at elevated laser powers. In spectra of a cytochrome c tryptic digest, all but one of the tryptic peptides were easily observed. Spectra of low molecular weight analytes dissolved in glycerol are very similar to FAB spectra of the same glycerol solution with added alkali salts. However, in many peptide and protein spectra, glycerol ion abundances are very low, and the alkali ions dominate the spectra at low mass. These spectra may correspond to wet and dry surface desorption conditions, respectively. The best spectra of the larger molecules were observed under dry conditions. In these initial experiments, we have obtained a sensitivity in the pico- to nanomole range and a mass resolution of about 300. The signal intensity is as good as that in conventional MALDI, and under optimal conditions, few background peaks appear, even at low mass.
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PMID:Graphite surface-assisted laser desorption/ionization time-of-flight mass spectrometry of peptides and proteins from liquid solutions. 863 76

The response of the estuarine human pathogen Vibrio vulnificus to starvation for carbon, nitrogen or phosphorus, or all three nutrients simultaneously (multiple-nutrient), was examined with respect to the maintenance of culturability during incubation at low temperature. V. vulnificus showed similar survival patterns during starvation for the individual nutrients when kept at 24 degrees C. On the other hand, cultures prestarved at 24 degrees C and then shifted to 5 degrees C maintained culturability at low temperature in a starvation-condition-dependent manner. Carbon and multiple-nutrient starvation were indistinguishable in their ability to mediate maintenance of culturability in the cold. Prolonged starvation for phosphorus had a similar effect, but nitrogen starvation did not allow for maintenance of culturability. Extracellular factors produced during starvation were not observed to have an effect on the culturability of cells incubated at low temperature. Protein synthesis during starvation for individual nutrients was analysed by two-dimensional PAGE of pulse-labelled proteins. Carbon and multiple-nutrient starvation gave nearly identical protein induction patterns involving at least 34 proteins, indicating that carbon starvation determines both responses. Nitrogen starvation for 1 h induced 24 proteins, while phosphorus starvation induced a set of 10 proteins after 1 h and about 40 proteins after 18 h. It is suggested that starvation for carbon or phosphorus induces maintenance of culturability of V. vulnificus incubated at low temperature via the synthesis of distinct sets of starvation-specific proteins.
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PMID:Analysis of starvation conditions that allow for prolonged culturability of Vibrio vulnificus at low temperature. 875 32

Cultures of Streptomyces lividans TK24 grown in defined media containing certain rapidly used carbon and nitrogen sources excreted high levels of organic acids. These were identified by HPLC and enzymic assays as pyruvic acid and 2-oxoglutaric acid. Acidification occurred only with glucose as the principal carbon source, and depended on the nitrogen source used. With nitrate as the sole nitrogen source, high levels of pyruvate and small amounts of 2-oxoglutarate were produced. Carbon from D[U-14C]glucose was converted into both organic acids. Combining glucose with a selection of amino acids as primary nitrogen/secondary carbon sources yielded less pyruvate and more 2-oxoglutarate. Carbon from both 14C-labelled glucose and amino acids was metabolized to both organic acids. Adding nitrate to this combination caused a reversion of the acid production pattern to that of the glucose-nitrate combination, as if the amino acids were absent. Addition of ammonium salts to any combination of carbon and nitrogen sources completely prevented organic acid formation.
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PMID:Organic acid excretion by Streptomyces lividans TK24 during growth on defined carbon and nitrogen sources. 896 15


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