Use Of Sulfide Research Articles

Sulfide-induced sulfide-quinone reductase activity in thylakoids of Oscillatoria limnetica.

Sulfide-dependent partial electron-transport reactions were studied in thylakoids isolated from cells of the cyanobacterium Oscillatoria limnetica, which had been induced to perform sulfide-driven anoxygenic photosynthesis. It was found that these thylakoids have the capacity to catalyze electron transfer, from sulfide to externally added quinones, in the dark. Assay conditions were developed to measure the reaction either as quinone-dependent sulfide oxidation (colorimetrically) or as sulfide-dependent quinone reduction (by UV dual-wavelength spectrophotometry). The main features of this reaction are as follows. (i) It is exclusively catalyzed by thylakoids of sulfide-induced cells. Noninduced thylakoids lack this reaction. (ii) Plastoquinone-1 or -2 are equally good substrates. Ubiquinone-1 and duroquinone yield somewhat slower rates. (iii) The apparent Km for plastoquinone-1 was 32 microM and for sulfide about 4 microM. Maximal rates (at 25 degrees C) were about 75 mumol of quinone reduced per mg of chlorophyll.h. (iv) The reaction was not affected by extensive washes of the membranes. (v) Unlike sulfide-dependent NADP photoreduction activity of these thylakoids, which is sensitive to all the specific inhibitors of the cytochrome b6f complex, the new dark reaction exhibited differential sensitivity to these inhibitors. 2-n-Nonyl-4-hydroxyquinoline-N-oxide was the most potent inhibitor of both light and dark reactions, working at submicromolar concentrations. 5-n-Undecyl-6-hydroxy-4,7-dioxobenzothiazole also inhibited the two reactions to a similar extent, but at 10 times higher concentrations than 2-n-nonyl-4-hydroxyquinoline-N-oxide. 2,5-Dibromo-3-methyl-6-isopropyl-p-benzoquinone, 2-iodo-6-isopropyl-3-methyl-2',4,4'-trinitrodiphenyl ether, and stigmatellin had no effect on the dark reaction at concentrations sufficient to fully inhibit the light reaction from sulfide. We propose that the sulfide-induced factor which enables the use of sulfide as the electron donor for anoxygenic photosynthesis in Oscillatria limnetica is a membrane-bound sulfide-quinone reductase. Its site of interaction is suggested to be either the cytochrome b6 (at the Qc quinone binding site or the bH site) or the plastoquinone pool. The analogy to other anoxygenic photosynthetic systems is discussed.

A rapid purification procedure and computer-assisted sulfide ion selective electrode assay for O-acetylserine sulfhydrylase from salmonella typhimurium

An improved method for purifying O-acetylserine sulfhydrylase from Salmonella typhimurium is described as well as a new computer-controlled assay making use of the sulfide ion selective electrode. The purification method uses gradient elution from Q-Sepharose Fast Flow and phenyl-Sepharose columns to give 75 mg (50% yield) of the enzyme starting from 300 g of starting material in 3 days. The sulfide electrode assay makes use of sulfide and calomel electrodes attached to a signal buffer which serves as an impedance match. The output of the signal buffer is linked in parallel to a strip chart recorder and a Keithley Model 575 data acquisition and control system. The system 575 is interfaced to a Packard-Bell AT computer. In addition, two BASIC computer programs have been written to convert potential measured by the electrode to sulfide concentration and to convert the time course data to rates.

Sulfide-dependent electron transport in thylakoids from the cyanobacterium Oscillatoria limnetica

Oscillatoria limnetica can use either water or sulfide as electron donor for photosynthesis, a property which they share with some other cyanobacteria (for reviews see [1,2]). The use of sulfide implies an anaerobic mode of growth in which photosystem II is bypassed and electrons are fed into the electron transport chain at the level of plastoquinone [3]. Sulfide-linked electron transport does not take off immediately; it requires an “induction phase” after the addition of sulfide. During this phase (a) protein(s) essential for anaerobic photosynthesis is (are) synthesized [4,5]. The nature of this (these) protein(s) is not clear; e.g. one might think of an electron transport component or of a protein that transports sulfide (or its oxidation product, sulfur) across the plasma membrane. To solve this problem, we are working with thylakoid preparations from 0. limnetica<; such preparations so far have been difficult to obtain.

Quenching of singlet and triplet excited aromatic hydrocarbons by sulphides :- the amine and sulphide enhanced photo-induced degradation of chloro- and cyanoaromatic hydrocarbons

Sulphides have been shown to be capable of quenching the excited singlet and triplet states of several aromatic hydrocarbons and their derivatives. The quenching is proposed to involve an electron transfer mechanism. The use of sulphides and amines to generate aromatic hydrocarbon radical cations from the excited states of these compounds has been utilised in order to carry out reductive decyanation reactions of cyanoaromatic hydrocarbons.

Qualitative analysis, without sulfide ion, of selected cations

Qualitative analysis of selected 11 cations can be accomplished without the use of sulfide.

Qualitative analysis and analytical chemical separations without the use of sulfides

The authors argue for the need of qualitative analysis, examine systems of qualitative analysis, and present a qualitative scheme that eliminates the need for sulfides.

Sur la thermogravimétrie des précipités analytiques: Dosage du germanium

Eight precipitates proposed for the gravimetric determination of germanium have been studied. It results from this critical examination that the best methods make use of sulfide, tannin and oxine. This last reagent permits the automatic determination of germanium (plateau from 50° to 115°).

On the Use of Sulphide of Calcium in the Treatment of Scabies

On the Use of Sulphide of Calcium in the Treatment of Scabies