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At least 19 recordsLinked to original sources
PubMed1977

Glycine metabolism by Pseudomonas aeruginosa: hydrogen cyanide biosynthesis.

Hydrogen cyanide (HCN) production by Pseudomonas aeruginosa in a synthetic medium is stimulated by the presence of glycine. Methionine enhances this stimulation but will not substitute for glycine as a stimulator of cyanogenesis. Threonine and phenylalanine are effective substitutes for glycine in the stimulation of HCN production. Glycine, threonine, and serine are good radioisotope precursors of HCN, but methionine and phenylalanine are not. Cell extracts of P. aeruginosa convert [14C]threonine to [14C]glycine. H14CN is produced with low dilution of label from either [1-14C]glycine or [2-14C]glycine, indicating a randomization of label either in the primary or secondary metabolism of glycine. When whole cells were fed [1,2-14C]glycine, cyanide and bicarbonate were the only radioactive extracellular products observed.

Carbon Radioisotopes↗
PubMedDate not supplied

The origin of proteins: Heteropolypeptides from hydrogen cyanide and water.

Evidence from laboratory and extraterrestrial chemistry is presented consistent with the hypothesis that the original heteropolypeptides on Earth were synthesized spontaneously from hydrogen cyanide and water without the intervening formation of chi-amino acids, a key step being the direct polymerization of atmospheric hydrogen cyanide to polyaminomalononitrile (IV) via dimeric HCN. Molecular orbital calculations (INDO) show that the most probable structure for (HCN)2 is azacyclopropenylidenimine. Successive reactions of hydrogen cyanide with the reactive nitrile side chains of IV then yield heteropolyamidines which are converted by water to heteropolypeptides. To study this postulated modification of a homopolymer to a heteropolymer, poly-chi-cyanoglycine (IX) was prepared from the N-carboxyanhydride of chi-cyanoglycine. Hydrolysis of IX, a polyamide analog of the polyamidine IV, yielded glycine. However, when IX was hydrolysed after being treated with hydrogen cyanide, other chi-amino acids were also obtained including alanine, serine, aspartic acid and glutamic acid, suggesting that the nitrile groups of IX (and therfore of IV) are indeed readily attacked by hydrogen cyanide as predicted. Further theoretical and experimental studies support the view that hydrogen cyanide polymerization along these lines is a universal process that accounts not only for the past formation of primitive proteins on Earth, but also for the yellow-brown-orange colors of Jupiter today and for the presence of water-soluble compounds hydrolyzable to chi-amino acids in materials obtained from environments as diverse as the moon, carbonaceous chondrites and the reaction chambers used to simulate organic synthesis in planetary atmospheres.

Amino Acids↗
PubMed1977

Deuterolysis of amino acid precursors: evidence for hydrogen cyanide polymers as protein ancestors.

Deuterolysis experiments suggest that hydrogen cyanide polymers rather than aminoacetonitriles are major precursors of alpha-amino acids obtained from spark reactions and other studies on chemical evolution. These results are consistent with the hypothesis that the original heteropolypeptides on the earth were synthesized spontaneously from hydrogen cyanide and water without the intervening formation of alpha-amino acids.

Amino Acids↗
PubMed1978

Acute toxicity of hydrogen cyanide to freshwater fishes.

Acute toxicity of hydrogen cyanide was determined at various temperatures from 4 degrees to 30 degrees C and oxygen concentrations of 3.36 to 9.26 mg/L on different life history stages of five species of fish: fathead minnow, Pimephales promelas Refinesque; bluegill, Lepomis macrochirus Rafinesque; yellow perch, Perca flavescens (Mitchill); brook trout, Salvelinus fontinalis (Mitchill); and rainbow trout, Salmo gairdneri Richardson. Median lethal threshold concentrations and 96-hr LC50's were established by flow-through type biassays. Acute toxicity varied from 57 microgram/L for juvenile rainbow trout to 191 microgram/L for field stocks of juvenile fathead minnows. Juvenile fish were more sensitive at lower temperatures and at oxygen levels below 5 mg/L. For most species juveniles were most sensitive and eggs more resistant.

Aging↗
PubMed1975

Heteropolypeptides from poly-alpha-cyanoglycine and hydrogen cyanide: a model for the origin of proteins.

Poly-alpha-cyanoglycine, a homopolymer synthesized from the N-carboxyanhydride of alpha-cyanoglycine, is converted by cumulative reaction of hydrogen cyanide to heteropolypeptides that can be hydrolyzed to protein amino acids, including glycine, alanine, valine, aspartic acid, and glutamic acid. These results are consistent with the hypothesis that the original heteropolypeptides on the earth arose spontaneously from hydrogen cyanide and water without the intervening formation of alpha-amino acids.

Chemical Phenomena↗
PubMed1978

Hydrogen cyanide poisoning: treatment with cobalt EDTA.

Three case reports are presented of employees who suffered varying degrees of exposure to hydrogen cyanide and their subsequent clinical courses following treatment with cobalt EDTA. A review of treatment modalities for CN- toxicity is given. It is concluded that, because of the degree of patient symptomatology associated from the use of cobalt EDTA, this therapy be reserved only for patients with the most severe degress of exposure to CN(-), and that in all other cases combined sodium nitrite and sodium thiosulphate therapy should be employed.

Accidents, Occupational↗
PubMed1977

Chemical evolution XXIX. Pyrimidines from hydrogen cyanide.

Dilute (0.1 M) solutions of HCN condense to oligomers at pH 8-9. Hydrolysis of these oligomers at pH 8.5 or with 6 N HCl yields 4,5-dihydroxypyrimidine, as the most abundant pyrimidine product along with orotic acid and 5-hydroxyuracil. These results, together with the earlier data, demonstrate that the three major nitrogen-containing classes of biomolecules could have originated from HCN on the primitive earth. The observation of the formation of orotic acid and 4-aminoimidazole-5-carboxamide by the hydrolysis of the HCN oligomers suggests that once the initially formed pyrimidines and purines were consumed, those life forms persisted which evolved enzymes for conversion of these intermediates to the pyrimidines and purines present in contemporary RNA.

Chemical Phenomena↗
PubMed1979

Hydrogen cyanide and cyanogen chloride formation by the myeloperoxidase-H2O2-Cl- system.

The chlorination of glycine by the myeloperoxidase-H2O2-Cl- system at acidic pH values yielded N-monochloroglycine and a mixture of HCN and ClCN. HCN was formed as a product of N-dichloroglycine decomposition and cyanogen chloride formation resulted from simultaneous chlorination of HCN by N-chloroglycine or directly by the myeloperoxidase-H2O2-Cl- system. HCN was readily chlorinated by the myeloperoxidase-H2O2Cl- system yielding cyanogen chloride. This dissociation constants of the myeloperoxidase-CN- complex were estimated as 2.5.10(-6)--1.15.10(-5) M within the pH range of 6.2 to 3.4, respectively. Chloride competed with cyanide for binding at the active site of myeloperoxidase. The lower the pH the more pronounced was the competitive effect of chloride. This accounted for chlorination by myeloperoxidase in the presence of CN-.

Binding Sites↗
PubMed1975

Hydrogen cyanide, a secondary metabolite of Pseudomonas aeruginosa.

Seventy-four of 110 strains of Pseudomonas aeruginosa tested produced detectable amounts of HCN from growth in 2% peptone or nutrient agar. Of the 25 species of12 bacterial and fungal genera tested, other than P. aeruginosa, only P. fluorescens and P. polycolor gave positive HCN tests. Cyanide is produced after cessation of active growth. Iron was stimulatory to cyanogenesis in concentration above 1 muM, while copper, zinc, cobalt, and manganese at concentrations of 20 muM had no effect. Cyanogenesis id dependent on the temperature of incubation within ranges which allow complete growth. Inorganic phosphate in concentrations between 90 and 300 mM allows growth but inhibits HCN production. Growth of cells anaerobically, using nitrate as the electron acceptor, results in low cyanide yields, which can be partially reversed by subsequent aerobic incubation. These results indicate that HCN is a secondary metabolite of P. aeruginosa.

Ferric Compounds↗