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Query: UNIPROT:P06889 (Mol)
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H atoms have been created by the photolysis of H2S. These then initiated reactions in mixtures involving acetylene-ammonia-water and ethylene-ammonia-water. In the case of the acetylene system, the products consisted of two amino acids, ethylene and a group of primarily cyclic thio-compounds, but no free sulfur. In the case of the ethylene systems, seven amino acids, including an aromatic one, ethane, free sulfur, and a group of solely linear thio-compounds were produced. Total quantum yields for the production of amino acids were approximately 3 x 10(-5) and approximately 2 x 10(-4) with ethylene and acetylene respectively as carbon substrates. Consideration is given of the mechanism for the formation of some of the products and implications regarding planetary atmosphere chemistry, particularly that of Jupiter, are explored.
J Mol Evol 1979 Jun 08
PMID:Hydrogen atom initiated chemistry. 45 69

The gas chromatograph mass spectrometer instrument of the Viking mission has demonstrated the absence of organic compounds in the immediate surface layer of the two landing sites. The demonstration of the successful operation of the instrument (comparison of ground-based test data with those obtained during interplanetary flight and the data from the surface of the planet) and its limitations (e.g., the detection of highly cross-linked polymers or polymeric carbon suboxide) are reviewed. The measurements for bound water are based on indirect data, the detectability of evolved carbon dioxide and ammonia is poor, and oxygen, liberated from the soil samples, can not be detected.
J Mol Evol 1979 Dec
PMID:The implications and limitations of the findings of the Viking organic analysis experiment. 52 60

Adenosine 5'-phosphoramidates form when solutions containing adenosine 5'-polyphosphates pnA (n greater than or equal to 3) or P1, P2-diadenosine 5'-diphosphate and amines are allowed to dry out. Mg ions catalyze these reactions. We have studied systems containing ammonia, imidazole, glycine, ethylenediamine and histamine. The yields of adenosine 5'-phosphoramidates range from 10-50% based on the nucleotide. The prebiotic significance of the reactions is discussed.
J Mol Evol 1977 Nov 25
PMID:Formation of nucleoside 5'-phosphoramidates under potentially prebiological conditions. 59 20

1. Arterial concentration and arterial-venous differences of glutamine across the kidney, forearm, hepato-splanchnic bed and brain were measured in patients with chronic renal insufficiency and in patients with normally functioning kidneys before and during chronic ammonium chloride acidosis. 2. In chronic renal insufficiency and in chronic metabolic acidosis there is a rise in glutamine release from the muscles and a suppression of glutamine uptake by the hepato-splanchnic bed and the brain. 3. In chronic renal insufficiency arterial glutamine concentrations is significantly increased in comparison with subjects with normal renal function and either normal acid-base balance or chronic metabolic acidosis. 4. In patients with chronic renal insufficiency the kidney extracts negligible amounts of glutamine, which cannot account for the renal ammonia production measured in the same patients.
Clin Sci Mol Med 1978 Oct
PMID:Effects of chronic renal insufficiency and metabolic acidosis on glutamine metabolism in man. 71 53

1. The effects of acute acid-base alterations on renal ammonia production and glutamine metabolism were studied in anaesthetized dogs. 2. Plasma glutamine rose with acidosis and also when both PCO2 and plasma HCO-3 were raised isohydrically. 3. Blood urea fell when acidosis was induced with hydrochloric acid. 4. The renal production of ammonia per ml of renal blood flow was increased in acidosis, but this was independent of the amount of glutamine delivered to the kidney. 5. The results indicate that acute acidosis affects production of urea and glutamine and increases the capacity of the renal cells to extract glutamine from blood.
Clin Sci Mol Med 1978 May
PMID:Effects of acute acid--base alterations on glutamine metabolism and renal ammoniagenesis in the dog. 75 Jan 52

When in the primeval atmosphere ammonia approached exhaustion, bacteria resembling clostridia developed mechanisms for nitrogen fixation. The fixation was continued by the photosynthetic bacteria. In the later, oxidizing, atmosphere the combined activities of the nitrificants and the denitrificants could lead to a large-scale cyclic regeneration of free nitrogen. The possibility of a descent of the nitrificants from hypothetical photosynthetic bacteria, which used ammonia as electron donor, is discussed. The anoxygenic atmosphere contained no nitrate, and therefore neither nitrate fermentation nor nitrate respiration were precursors of aerobic respiration. This evolved from photosynthesis. In nitrate fermentation, nitrate serves only as an incidental electron acceptor; this process is merely an evolutionary sideline. Nitrate respiration evolved from aerobic respiration. While in present conditions the reaction of nitrogen with oxygen and water to give nitrate is exergonic and possibly occurs at a low rate, the antagonistic action of the denitrificants maintains the stationary concentrations of nitrogen and oxygen in the air.
J Mol Evol 1975 Dec 31
PMID:The history of inorganic nitrogen in the biosphere. 76 87

The activity of yeasts citrate synthase in cells grown under different hypoxic conditions has been investigated. A linear relationship between the citrate synthase activity and the respiratory capacity of the cells has been found. When Saccharomyces cerevisiae was grown on fermentable substrates the activity decreased as the concentration of sugars in the medium increased. The enzyme of the yeast Rhodoturula showed a high activity in spite of the existence of high sugar concentration in the culture medium. Neither feed-back repression by glutamate nor feed-forward induction by ammonia has been found in bakers' yeast. The results suggest that the regulation of the enzyme by oxygen availability takes place by the ""de novo'' synthesis of the enzyme.
Mol Cell Biochem 1976 Sep 30
PMID:Regulation of the level of yeasts citrate synthase by oxygen availability. 79 Jan 60

The role and relative contributions of different forms of energy to the synthesis of amino acids and other organic compounds on the primitive earth, in the parent bodies or carbonaceous chondrites, and in the solar nebula are examined. A single source of energy or a single process would not account for all the organic compounds synthesized in the solar system. Electric discharges appear to produce amino acids more efficiently than other sources of energy and the composition of the synthesized amino acids is qualitatively similar to those found in the Murchison meteorite. Ultraviolet light is also likely to have played a major role in prebiotic synthesis. Although the energy in the sun's spectrum that can be absorbed by the major constituents of the primitive atmosphere is not large, reactive trace components such as H2S and formaldehyde absorb at longer wavelengths where greater amounts of energy are available and produce amino acids by reactions involving hot hydrogen atoms. The thermal reaction of CO + H2 + NH3 on Fischer-Tropsch catalysts generates intermediates that lead to amino acids and other organic compounds that have been found in meteorites. However, this synthesis appears to be less efficient than electric discharges and to require a special set of reaction conditions. It should be emphasized that after the reactive organic intermediates are generated by the above processes, the subsequent reactions which produce the more complete biochemical compounds are low temperature homogenous reactions occurring in an aqueous environment.
J Mol Evol 1976 Dec 31
PMID:Origin of organic compounds on the primitive earth and in meteorites. 101 32

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.
J Mol Evol 1975 Aug 05
PMID:Ultraviolet-gas phase and -photocatalytic synthesis from CO and NH3. 115 1

1. Gluconeogenesis from lactate or from glutamine is inhibited by 90-100% by sodium quinolinate (1 mmol/l) or 3-mercaptopicolinate (150 nmol/l) in the perfused rat kidney. L-Tryptophan is not metabolized and is without effect. 2. Lactate uptake and glucose production are inhibited to the same degree by 3-mercaptopicolinate in the kidneys of well-fed or starved rats. 3. Inhibition of gluconeogenesis from glutamine (1 mmol/l) by 3-mercaptopicolinate is accompanied by 50% inhibition of ammonia production, and 34% inhibition of glutamine uptake, in the kidneys of acidotic rats. Ammonia production from glutamine was not inhibited in kidneys from non-acidotic rats. 4. It is concluded that the increased rate of gluconeogenesis from glutamine which occurs in acidotic rats is an essential and primary event regulating all of the increase in ammonia formation.
Clin Sci Mol Med 1976 Jun
PMID:Effect of inhibition of gluconeogenesis on ammonia production in the perfused rat kidney. 127 56


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