Topic
Cyanide
About: Cyanide is a research topic. Over the lifetime, 13990 publications have been published within this topic receiving 247116 citations. The topic is also known as: cyanides & cyanide salt.
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TL;DR: This chapter provides the spectrophotometric, titrimetric, nitrite, and cyanide assay for the differentiation of glutathione S-transferases.
Abstract: Publisher Summary This chapter provides the spectrophotometric, titrimetric, nitrite, and cyanide assay for the differentiation of glutathione S-transferases. Spectrophotometric assays depend upon a direct change in the absorbance of the substrate when it is conjugated with glutathione (GSH). Because each of the reactions is catalyzed at a finite rate in the absence of enzyme, care is needed to reduce nonenzymatic catalysis by minimizing substrate concentrations and by decreasing pH wherever necessary. Titrimetric assay is based on the principle that the conjugation of alkyl halides with GSH can be measured titrimetrically. Although acid production accompanies many of the transferase catalyzed reactions in which thioethers are formed, titrimetry is only used when more convenient assays are not available. Nitrite assay is based on the principle that nitrite is released when GSH reacts with nitroalkanes or with organic nitrate esters. The nitrite can be assayed as the limiting factor in a diazotization reaction with sulfanilamide that produces a readily quantitatable pink dye. Cyanide assay is based on the fact that when glutathione transferases catalyze the attack of the glutathione thiolate ion on the electrophilic sulfur atom of several organic thiocyanates, it results in the formation of an asymmetric glutathionyl disulfide and cyanide. Cyanide can be readily quantitated by a calorimetric method.
2,074 citations
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TL;DR: This chapter discusses the cytochrome c oxidase from beef heart mitochondria, which is inhibited by cyanide, azide, hydroxylamine, and sodium sulfide.
Abstract: Publisher Summary This chapter discusses the cytochrome oxidase from beef heart mitochondria. Cytochrome c oxidase is mostly assayed by the spectrophotometric method. The rate of oxidation of ferrocytochrome c is measured by following the decrease in the absorbency of its α-band at 550 mμ. The activity of cytochrome c oxidase may be defined in terms of the first-order velocity constant. The oxidation-reduction components of isolated cytochrome c oxidase are cytochrome a, cytochrome a 3 , and copper. Cytochrome c oxidase can also be assayed by measuring oxygen uptake either manometrically or polarographically. Two procedures for purifying cytochrome c oxidase from beef heart mitochondria are described. The enzyme obtained by procedure I is less pure based on its activity and spectrum. Preparations of cytochrome oxidase are stored best in 0.25M sucrose (pH 7.0-7.5) at –15° at a protein concentration of 1 mg/ml. The composition of cytochrome oxidase prepared by procedure II is tabulated. Ferrocytochrome c donates electrons directly to cytochrome oxidase. The reaction as measured spectrophotometrically obeys first-order reaction kinetics. Cytochrome oxidase is inhibited by cyanide, azide, hydroxylamine, and sodium sulfide.
1,244 citations
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TL;DR: This tutorial review focuses on recent developments arising from studies of optical sensors for cyanide ions, which are categorized by approaches involving cyanide selective receptors, the utilization of metal coordinated complexes, and chemodosimeters.
Abstract: This tutorial review focuses on recent developments arising from studies of optical sensors for cyanide ions, which are categorized by approaches involving cyanide selective receptors, the utilization of metal coordinated complexes, and chemodosimeters.
989 citations
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TL;DR: A hypothesis, that potato plant growth is depressed in short potato rotation soils by the microbial production of cyanide in the rhizosphere by competing with cyanide-producing organisms for Fe3+.
Abstract: Inhibition of root cell energy metabolism is suggested to be responsible for potato yield reductions in short potato-rotation soils. Hydrogen cyanide is the microbial metabolile possibly involved in inhibition of energy metabolism. This is supported by the following observations: (1) approximately 50% of potato rhizosphere pseudomonads was shown to produce cyanide in vitro; (2) 5 μM HCN inhibited cytochrome oxidase respiration by at least 40% in intact potato roots in vitro; (3) cyanide production in vitro by Pseudomonas sp. isolate WCS361 depended on the Fe3+ concentration of the medium. Growth promoting fluorescent Pseudomonas spp isolates WCS374 and WCS358 did not produce cyanide in vitro. A hypothesis, that potato plant growth is depressed in short potato rotation soils by the microbial production of cyanide in the rhizosphere is discussed. In such soils, bacteria producing specific siderophores increase growth by competing with cyanide-producing organisms for Fe3+.
910 citations
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TL;DR: It is concluded that bacterial cyanide is an important but not the only factor involved in suppression of black root rot in Pseudomonas fluorescens CHA0.
Abstract: Pseudomonas fluorescens CHA0 suppresses black root rot of tobacco, a disease caused by the fungus Thielaviopsis basicola. Strain CHA0 excretes several metabolites with antifungal properties. The importance of one such metabolite, hydrogen cyanide, was tested in a gnotobiotic system containing an artificial, iron-rich soil. A cyanidenegative (hcn) mutant, CHA5, constructed by a gene replacement technique, protected the tobacco plant less effectively than did the wild-type CHA0. Complementation of strain CHA5 by the cloned wild-type hcn+ genes restored the strain's ability to suppress disease. An artificial transposon carrying the hcn+ genes of strain CHA0 (Tnhcn) was constructed and inserted into the genome of another P.fluorescens strain, P3, which naturally does not produce cyanide and gives poor plant protection. The P3::Tnhcn derivative synthesized cyanide and exhibited an improved ability to suppress disease. All bacterial strains colonized the roots similarly and did not influence significantly the survival of T.basicola in soil. We conclude that bacterial cyanide is an important but not the only factor involved in suppression of black root rot.
660 citations