Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Nitrogen Compounds”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59Linked to original sources
PubMed1991

Participation of proteinase yscA in the in vitro formation of the smaller subunit of glycogen phosphorylase in extracts of Saccharomyces cerevisiae.

Analyses by sodium dodecyl sulphate-polyacrylamide gradient-gel electrophoresis and Western blotting of the proteins from boiled cell samples from all growth phases of yeast cultures, and from all stages of extract preparation indicate that the smaller subunit (s-monomer), which is found in purified glycogen phosphorylase (EC 2.4.1.1) from baker's yeast, is not present in the living cell. It is observed in extracts of Saccharomyces carlsbergensis and S. cerevisiae after incubation at ambient temperatures or even after storage in the frozen state at -25 degrees C. Its formation is sensitive towards pepstatin A, and it is absent from extracts of several mutants of S. cerevisiae that do not contain active proteinase yscA (EC 3.4.33.6). When purified proteinase yscA is added to the extracts of these mutants, the formation of s-monomer is restored. When the proteinase yscA-deficient strains are grown with a reduced amount of complex nitrogen compounds, the slightly smaller sc-monomer is formed in their extracts. This event must be attributed to a different proteinase, since it is sensitive towards p-hydroxymercuriphenylsulphonate, but not towards pepstatin A. The N-terminal amino acid of the sc-monomer was found to be blocked, as in the case of the native l-monomer, but not the s-monomer.

Aspartic Acid Endopeptidases↗
PubMed1994

Molecular cloning, tissue expression of human xanthine dehydrogenase.

Xanthine dehydrogenase (XDH, EC 1.1.1.204) is a molybdenum iron-sulphur flavin hydroxylase which oxidizes a variety of purines, pterins and other heterogenic nitrogen compounds, serving as a rate-limiting enzyme in nucleic acid degradation. In this work, we have isolated and sequenced cDNA clones of human liver XDH. The obtained cDNA covers 4577 bases of human liver XDH mRNA with a 63 bp 5'-end untranslated region and a 515 bp 3'-end untranslated region. A termination codon TGA and a polyadenylation signal AATAAA were identified. An open reading frame encodes 1333 amino acid residues. The assignment of the N-terminal was confirmed by directly sequencing that region of purified human milk XDH. Northern blot analysis shows that the human XDH gene is widely expressed in human tissues.

Amino Acid Sequence↗
PubMed1994

Assignment of human xanthine dehydrogenase gene to chromosome 2p22.

Xanthine dehydrogenase (XDH, EC 1.1.1.204) oxidizes a variety of purines, pterins, and other heterogenic nitrogen compounds, serving as a rate-limiting enzyme in nucleic acid degradation. The genetic defect of XDH results in hereditary xanthinuria and other disorders in purine metabolism. Based on the cloning and sequencing results of human XDH cDNA in our laboratory, we studied the localization and sublocalization of the XDH gene. A Version 3.0 human-hamster somatic cell hybrid PCRable DNA panel and specific PCR primers derived from human XDH cDNA for amplification were used to assign the XDH gene to human chromosome 2. The fidelity of the PCR product was confirmed by nucleotide sequencing the PCR product. The assignment of the XDH gene to chromosome 2 at band p22 was established by fluorescence in situ hybridization on human metaphase chromosomes using a clone from a pWE 15 cosmid library containing the XDH gene. The results should be useful for further studies of the molecular basis for hereditary xanthinuria and other genetic disorders related to abnormal XDH activity.

Animals↗
PubMed2001

Detection of natural abundance nitrogen-15 through phosphorus-31 using pulsed field gradients.

NMR characterization of natural abundance (15)N in phosphorus-nitrogen compounds can be performed through (31)P using inverse detection methods. When the (31)P-(15)N scalar coupling is small, its observation is greatly disturbed by the residual signal coming from the 99.6% abundant (14)N isotopomer that usually is not completely suppressed by the phase cycle of the sequence. The combined use of pulsed field gradients to suppress this residual signal and the enhanced sensitivity (31)P, (15)N[(1)H]-esHSQC experiment affords artifact-free spectra with good signal-to-noise ratio, which allows the accurate measurement of (15)N NMR parameters such as chemical shifts and coupling constants with the benefits of phosphorus detection.

Journal Article↗
PubMed1993

Subsurface agricultural irrigation drainage: the need for regulation.

Subsurface drainage resulting from irrigated agriculture is a toxic threat to fish and wildlife resources throughout the western United States. Studies by the U.S. Department of the Interior show that migratory waterfowl have been poisoned by drainwater contaminants on at least six national wildlife refuges. Allowing this poisoning to continue is a violation of the Migratory Bird Treaty Act under U.S. Federal law. Critical wetlands and waterfowl populations are threatened in both the Pacific and Central flyways. The public is also at risk and health warnings have been issued in some locations. Subsurface irrigation drainage is a complex effluent containing toxic concentrations of trace elements, salts, and nitrogenous compounds. Some of the contaminants are classified by the U.S. Environmental Protection Agency (EPA) as priority pollutants and they can be present in concentrations that exceed EPA's criteria for toxic waste. The on-farm drainage systems used to collect and transport this wastewater provide point-source identification as well as a mechanism for toxics control through the National Pollutant Discharge Elimination System (NPDES) permit process. A four-step approach is presented for dealing with irrigation drainage in an environmentally sound manner. This regulatory strategy is very similar to those commonly used for industrial discharges and includes site evaluation, contaminant reduction through NPDES, and compliance monitoring. The EPA must recognize subsurface irrigation drainage as a specific class of pollution subject to regulation under the NPDES process. Active involvement by EPA is necessary to ensure that adequate controls on this wastewater are implemented.

Agriculture↗
PubMed1983

Effect of exogenous amino acids on the contractility and nitrogenous metabolism of anoxic heart.

The effect of exogenous glutamic acid and arginine on the contractility of isolated perfused rat heart and on the metabolism of some nitrogenous compounds was studied. Sixty-minute anoxic perfusion (95% N2 + 5% CO2) led to a fall in developed isovolumic pressure and an elevation in diastolic pressure, to an increase in the production of alanine, glutamine, and ammonia, and to a decrease in the tissue content of aspartate and glutamate. The total pool of free amino acids and taurine under these conditions remained unchanged. Subsequent 40-min reoxygenation partially restored the contractile function. Addition of 3.5 mM glutamic acid or 5 mM arginine into the perfusate before anoxia resulted in a higher level of developed pressure and a lower level of diastolic pressure during anoxia and almost complete recovery of cardiac function after subsequent reoxygenation. Both amino acids had no effect on ammonia formation by the anoxic heart but enhanced its binding in myocardial tissue via formation of glutamine and urea. It is suggested that the exogenous amino acid effect on anoxic heart is mediated by activation of substrate phosphorylation rather than the ability to bind tissue ammonia.

Alanine↗
PubMed1995

Expression of ferredoxin-dependent glutamate synthase in dark-grown pine seedlings.

Pine seedlings are able to accumulate chlorophylls and develop green plastids in a light-independent manner. In this work, we have characterized ferredoxin-dependent glutamate synthase (EC 1.4.7.1; Fd-GOGAT), a key enzyme in nitrogen interconversion during this process. Fd-GOGAT has been purified about 170-fold from cotyledons of maritime pine (Pinus pinaster). As occurs in angiosperms, the native enzyme is a single polypeptide with an apparent molecular mass of 163-168 kDa that is confined to the chloroplast stroma. Polyclonal antibodies generated against the purified enzyme were used to immunoscreen a lambda gt11 expression library from Scots pine (Pinus sylvestris) seedlings and partial cDNA clones were isolated and characterized. The clone with the longest cDNA insert (pGOP44) contained the codification for the C-terminal (550 amino acids) of the pine Fd-GOGAT polypeptide. Immunological cross-reactivity and comparative amino sequence analysis revealed that Fd-GOGAT is a well conserved protein in higher plants. Western blot analyses showed that protein was expressed in chloroplast-containing pine tissues and this expression pattern was not affected by exogenously supplied nitrogen. Fd-GOGAT mRNA, polypeptide and enzyme activity accumulated in substantial amounts in dark-grown pine seedlings. The presence of a functional Fd-GOGAT may be important to provide the required glutamate for the biosynthesis of nitrogen compounds during chloroplast biogenesis in the dark.

Amino Acid Oxidoreductases↗
PubMed1995

Frequency and spectrum of p53 mutations in gastric cancer--a molecular genetic and immunohistochemical study.

The p53 tumour-suppressor gene plays an important role in gastric carcinogenesis. In an analysis of the spectrum of mutations of the p53 gene seen in 56 primary gastric carcinomas of various types and grades of differentiation, the entire coding sequence (exons 2-11) of the p53 gene was screened by single-strand conformation polymorphism analysis and direct genomic sequencing of polymerase chain reaction products. Intragenic restriction site polymorphisms and the probe YNZ22 were used for the detection of loss of heterozygosity (LOH) of the p53 gene locus on chromosome 17p. p53 overexpression was studied with the anti-p53 antibody CM-1. A total of 21 somatic alterations of the p53 gene were found. Twenty were base-pair substitutions, and one was an eight base-pair deletion. Six tumours with p53 mutations revealed LOH. Abnormalities in p53 expression were found in 17 tumour samples, of which 16 had gene mutations. The spectrum of mutations observed was consistent with the predicted spectrum for dietary mutagens associated with the metabolism of nitrogenous compounds, resulting in deamination of nucleic acids. Our findings suggest that p53 could be a primary target for mutations associated with dietary carcinogens in gastric carcinogenesis.

Adenocarcinoma↗
PubMed1988

Biological effects in a chemical factory with mutagenic exposure. I. Cytogenetic and haematological parameters.

Analysis in two independent laboratories demonstrated no significant differences in chromosome aberrations or micronuclei in lymphocytes from peripheral blood between workers in a chemical factory (exposed to a mixture of chemicals, such as piperazine, low levels of ethylene oxide and formaldehyde, aromatic nitrogen compounds, and other aromatic compounds) compared to unexposed control subjects. The chemical workers had significantly higher counts of lymphocytes (3.57 vs. 2.82 X 10(9)/l; P less than 0.001), eosinophils (0.27 vs. 0.20 X 10(9)/l; P = 0.005), and basophils (0.06 vs. 0.05 X 10(9)/l; P = 0.01) than the controls. Twenty workers exposed to piperazine had higher total numbers of B-lymphocytes than control subjects.

Adult↗
PubMed1979

Manganese deficiency leads to elevated amino acid pools in citric acid accumulating Aspergillus niger.

Free amino acid pools have been investigated in a citric acid accumulating strain of Aspergillus niger during batch growth under manganese sufficient and deficient conditions by means of an improved chromatographic method. Studies on the mycelial content of several nitrogenous compounds under manganese sufficient and deficient conditions showed that manganese deficiency resulted in lower amino acid pool sizes during trophophase and considerable accumulation during idiophase, and in a reduction of the protein and nucleic acid contents. Addition of cycloheximide to mycelia grown with sufficient manganese also caused an elevation of free amino acid pool sizes, thus indicating that impairment of protein synthesis by manganese deficiency is responsible for the observed rise in amino acid concentration. Furthermore it was observed that the manganese deficient mycelia excreted high amounts of all amino acids suggesting that manganese deficiency may also affect membrane permeability.

Amino Acids↗
PubMed1992

Evaluation of the Pro-Lab ID ring system for the identification of medically important yeasts.

We evaluated 151 coded isolates of medically important yeast species belonging to the genera Candida, Cryptococcus, Geotrichum, Rhodoturula, Saccharomyces and Torulopsis using the newly developed rapid Pro-Lab Identification Ring, PL 960 system (PLID-Ring). All isolates were concurrently identified by the API 20C and conventional procedures comprising macro- and micromorphology, assimilation and fermentation of various carbon and nitrogen compounds. The PLID-Ring system identified isolates of Candida albicans, C. kefyr, C. krusei, C. lusitaniae, C. parapsilosis, Rhodotorula rubra, and Torulopsis glabrata with 100% accuracy in 24 h. This system identified C guilliermondii and S. cerevisiae isolates with an accuracy of 90% and 86%, respectively, while those belonging to Cr. neoformans, T. candida (= C. famata), C. rugosa and C. tropicalis were identified with 38.4%, 50%, 12.5% and 50% accuracy, respectively. Three isolates of Cr. laurentii were not identified by the PLID-Ring system. The overall accuracy of the PLID-Ring system was 81.45% (123 of 151 isolates). However, the system does not include species such as Cr. laurentii in its data base. When these three Cr. laurentii isolates were excluded from the evaluation, the accuracy of the PLID-Ring system increased from 81.45% to 83.1%.

Candida↗
PubMed1975

Carcinogenesis.

An examination has been made of the major chemicals which are known to be carcinogenic, either in animals or in humans. As a result, a generalized type of chemical property seems to be a prerequisite for the carcinogenic activity. In most cases, this is some kind of reactive electrophilic intermediate produced directly from the carcinogen or from one of its immediate metabolites. This electrophilic reagent is generally a positively charged ion of some kind. In the case of the hydrocarbons it seems to be an incipient carbonium ion; in the case of nitrogen compounds, it is a corresponding nitronium ion. There are a number of possible substrate materials (nucleophilic) in a cells, but the dominant one which has been suspected is the nucleic acid component, either the DNA or the RNA. The bases of these materials all have extra pi electrons susceptible to attach by the electrophiles of the carcinogen. Such a modification, particularly of the DNA, could lead to either major or minor changes in the genetic composition of the cell. Minor changes are usually rectifiable or are not visible, and this would include a large variety of point mutations.

2-Acetylaminofluorene↗
PubMed1995

Stimulation of conversion rates and bacterial activity in a silage-fed two-phase biogas process by initiating liquid recirculation.

The effects of liquid recirculation on a liquefaction-acidogenic reactor in an anaerobic two-phase digesting system operating with grass-clover silage was studied during 40 days after initiating recirculation of effluent from the methanogenic reactor to the liquefaction-acidogenic reactor. An increase in alkalinity and, thus, an increase in pH from 5.2 to 6.0 occurred in the liquefaction-acidogenic reactor. During the same period, a 10-fold increase (from 0.2 to 1.9 g.l-1.h-1) in the degradation rate of mannitol and an almost 9-fold increase in the activity of hydrogenotrophic methanogens was observed. The estimated number of these bacteria increased by one order of magnitude. The average degradation rate of lactate increased 3-fold, probably as a consequence of the more efficient hydrogen consumption by the hydrogenotrophic methanogens. An observed increase in net mineralization of organic nitrogen compounds was probably the main reason for an enhanced net production of organic acids (from 0.2 to 0.9 g.l-1.d-1). The liquefaction of cellulose and hemicellulose was low from the start of recirculation (3% and 20% reduction, respectively) and did not seem to be affected by the liquid recirculation. This was in accordance with the low number of cellulose degraders (4.0 x 10(2) counts.ml-1) observed. The results from this investigation show that the initiation of liquid recirculation in silage-fed two-phase biogas processes will stimulate the activity of hydrogenotrophic methanogens in the liquefaction-acidogenic reactor. This will lead to more thermodynamically favourable conditions for acidification reactions which are dependent upon interspecies transfer of reducing equivalents.

Biodegradation, Environmental↗
PubMed1986

Effect of the add-back process on the free amino acid pool of potatoes.

The major losses in nitrogen and free amino acids (FAA) of the potato during the add-back (A-B) process were in the pre-cooking and mash-mixing steps (Fig. 1). These losses were due to leaching of nitrogen compounds into the processing water and heating. The FAA pool of the potato is composed mainly of the amides (asparagine and glutamine), aspartic and glutamic acids (approx. 53%). These amino acids were degraded substantially during the add-back process. There was also a significant loss in valine, threonine, serine, leucine, phenylalanine, and arginine, but no change in gamma-aminobutyric acid (GABA).

Amines↗
PubMed1975

Ultraviolet-gas phase and -photocatalytic synthesis from CO and NH3.

The major photoproduct obtained on irradiation of gaseous NH3 and CO mixtures is ammonium cyanate; lesser amounts of urea, biurea, biuret semi-carbazide, formamide and cyanide were observed. The formation of the major gas phase photolysis product may be rationalized by the following reaction sequence: (see article). Urea is probably formed from NH4NCO in a thermal reaction while formamide may result from the disproportionation of NH2CO. Photocatalytic syntheses of 14C-urea, -formamide, and -formadehyde are effected by irradiation of 14CO and NH3 in the presence of Vycor, silica gel, or volcanic ash shale surfaces. These syntheses are catalyzed by ultraviolet wavelengths longer than those absorbed by the gaseous reactants. The syntheses are also effected when the surface material is first irradiated in the presence of CO followed by a dark incubation with NH3. Apparently, the initiating step is a light dependent formation of a reactive form of CO on the surface. A discussion is given on the possible contribution of these reactions to the abiotic synthesis of organic nitrogen compounds on Mars, on the primitive Earth and in interstellar space.

Ammonia↗
PubMed2001

Global tropospheric ozone dynamics. Part I: Tropospheric ozone precursors.

An overview of the tropospheric ozone changes is presented focussing mainly on the tropospheric ozone precursors. The complexity of the problem is shown through the consideration of a great number of relevant substances, like nitrogen compounds, volatile organic compounds, peroxyacetyl nitrate, hydroxyl radical, carbon monoxide, alkyl nitrates. The up-to-date knowledge on the relevant numerical modelling is presented in Part II.

Atmosphere↗
PubMed2002

Effect of melatonin on hyperlipidemic nephropathy under constant light exposure.

Studies have shown anti-hyperlipidemic actions of melatonin, with pharmacological doses inducing changes in cholesterol levels. This study was designed to evaluate the effect of melatonin on adriamycin-induced (25mg/kg b.w., i.p.) hyperlipidemia under constant light exposure. Melatonin was injected i.p. (1,000 microg/kg b.w./day). Triglycerides, total cholesterol, high-density lipoprotein cholesterol, light-density lipoprotein cholesterol, non-proteic nitrogen compounds (urea and creatinine levels), total protein in serum, proteins eliminated in the urine and melatonin levels in serum and kidney were determined. Results show a decrease in melatonin levels induced by both adriamycin and constant light. Likewise, adriamycin induced significant increases in triglycerides, total cholesterol and light-density lipoprotein cholesterol, and lowered high-density lipoprotein cholesterol levels. Constant light exposure also prompted an increase in LDL-c levels and a decrease in HDL-c values, and intensified the effects of adriamycin on these two lipoproteins. All changes induced by adriamycin and constant light were reverted toward normality by melatonin administration.

Animals↗
PubMed2003

Bacterial oligopeptide-binding proteins.

This review focuses on bacterial oligopeptide-binding proteins, which form part of the oligopeptide transport system belonging to the ATP-binding cassette family of transporters. Depending on the bacterial species, these binding proteins (OppA) capture peptides ranging in size from 2 to 18 amino acids from the environment and pass them on to the other components of the oligopeptide transport system for internalisation. Bacteria have developed several strategies to produce these binding proteins, which are periplasmic in Gram- bacteria and membrane-anchored in Gram+, with a higher stoichiometry (probably necessary for efficient transport) than the other components in the transport system. The expression of OppA-encoding genes is clearly modulated by external factors, especially nitrogen compounds, but the mechanisms of regulation are not always clear. The best-understood roles played by OppAs are internalisation of peptides for nutrition and recycling of muropeptides. It has, however, recently become clear that OppAs are also involved in sensing the external medium via specific or non-specific peptides.

Bacterial Physiological Phenomena↗