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PubMed1981

Use of reduced sulfur compounds by Beggiatoa sp.

A strain of Beggiatoa cf. leptomitiformis (OH-75-B, clone 2a) was isolated which is unique among reported strains in its ability to deposit internal sulfur granules from thiosulfate. It also deposited these characteristic granules (as all BEggiatoa species do) from sulfide. In cultures where growth was limited by exhaustion of organic substrates, these granules generally comprised about 20% of the total cell weight. With medium containing acetate and thiosulfate, no measurable utilization of thiosulfate or deposition of elemental sulfur (S0) took place until after the exponential growth phase. Neither sulfide nor thiosulfate added an increment to heterotrophic growth yield except for the weight of the deposited S0. The deposition of S0 from thiosulfate was probably a disproportionation in which S0 and sulfate were produced in a 1:1 ratio. Some of the S0 was further oxidized to sulfate. No autotrophic or mixotrophic growth was demonstrated for this strain. When inoculated in small, well-dispersed quantities into yeast extract medium, this strain grew only after long lags. Addition of the enzyme catalase eliminated initial lags and increased growth rates slightly. In contrast, catalase had no influence on growth rate when added to mineral medium containing acetate. In yeast extract medium, the inhibition of growth rate was presumably because of peroxides. Addition of thiosulfate was almost as effective as catalase in eliminating this inhibition. The S0 granules which, in this case, were deposited during the exponential growth phase, appeared to be partly responsible for this relief. This strain of Beggiatoa sp. remained active for at least 5 days under strictly anaerobic conditions, and under those conditions, it increased its dry weight by about 2.5-fold. Anaerobic "growth" and maintenance required the presence of an energy source, such as acetate. When cells containing much internal S0 were transferred to an organic anaerobic medium, a substantial portion of the internal S0 was eventually converted to sulfide.

Acetates↗

PubMed1993

Cloning of the phs genetic locus from Salmonella typhimurium and a role for a phs product in its own induction.

The Salmonella typhimurium phs chromosomal locus essential for the reduction of thiosulfate to hydrogen sulfide was cloned, and some features of its regulation were examined. The phs locus conferred H2S production on Escherichia coli, suggesting that it contains the structural gene for thiosulfate reductase. H2S production by the E. coli host was, as in S. typhimurium, suppressed by nitrate or glucose in the growth medium. The presence of plasmid-borne phs genes in a S. typhimurium chl+ host containing a chromosomal phs::lacZ operon fusion was found to significantly increase the relative induction efficiency of beta-galactosidase by thiosulfate. These results are consistent with a model for phs regulation in which the true inducer is not thiosulfate per se and in which the action of a phs-encoded molybdoprotein, possibly the reductase itself, converts thiosulfate into a compound that resembles the true inducer more closely than does thiosulfate.

Chromosomes, Bacterial↗

PubMed1996

Reduced sulfur compound oxidation by Thiobacillus caldus.

The oxidation of reduced inorganic sulfur compounds was studied by using resting cells of the moderate thermophile Thiobacillus caldus strain KU. The oxygen consumption rate and total oxygen consumed were determined for the reduced sulfur compounds thiosulfate, tetrathionate, sulfur, sulfide, and sulfite in the absence and in the presence of inhibitors and uncouplers. The uncouplers 2,4-dinitrophenol and carbonyl cyanide m-chlorophenyl-hydrazone had no affect on the oxidation of thiosulfate, suggesting that thiosulfate is metabolized periplasmically. In contrast, the uncouplers completely inhibited the oxidation of tetrathionate, sulfide, sulfur, and sulfite, indicating that these compounds are metabolized in the cytoplasm of T. caldus KU. N-Ethylmaleimide inhibited the oxidation of tetrathionate and thiosulfate at the stage of elemental sulfur, while 2-heptyl-4-hydroxyquinoline-N-oxide stopped the oxidation of thiosulfate, tetrathionate, and elemental sulfur at the stage of sulfite. The following intermediates in the oxidation of the sulfur compounds were found by using uncouplers and inhibitors: thiosulfate was oxidized to tetrathionate, elemental sulfur was formed during the oxidation of tetrathionate and sulfide, and sulfite was found as an intermediate of tetrathionate and sulfur metabolism. On the basis of these data we propose a model for the metabolism of the reduced inorganic sulfur compounds by T. caldus KU.

Ethylmaleimide↗

PubMed2002

Fatal and nonfatal poisoning by hydrogen sulfide at an industrial waste site.

An adult man (A) entered a pit to collect seepage at an industrial waste site in Japan. As he suddenly lost consciousness, three colleagues (B, C, D) entered the pit to rescue him. All of these men lost consciousness in the pit. Two workers (A and B) died soon after the accident, one worker (C) died 22 days after the accident, and one worker (D) survived. Since hydrogen sulfide gas was detected in the atmosphere of the pit, gas poisoning was suspected. Toxicological analyses of sulfide and thiosulfate, a metabolite of sulfide, in blood and urine of the victims were made using the extractive alkylation technique combined with gas chromatography/mass spectrometry (GC/MS). Sulfide was detected in the blood of A and B at levels of 0.13 and 0.11 mg/L, respectively, somewhat higher than in healthy persons. Thiosulfate was detected in whole blood of deceased victims A and B, in the plasma of deceased victim C, at concentrations of 10.53, 4.59, and 4.14 mg/L, respectively. These values were similar to those found in fatal cases of hydrogen sulfide poisoning. Thiosulfate was not detected in the plasma of survivor D. With respect to urine samples, thiosulfate was the highest in the non-acute death victim C (137.20 mg/L), followed by that in the survivor D (29.34 mg/L), and low (0.90 mg/L) and not detected in the acute death victims, A and B, respectively. Based on these results, all four patients were victims of hydrogen sulfide poisoning. The concentrations of thiosulfate in blood and urine were more useful than that for sulfide for determining hydrogen sulfide poisoning. Thiosulfate in urine was the only indicator of hydrogen sulfide poisoning in the non-fatal victim.

Fatal Outcome↗

PubMed1986

Oxidative inactivation of the enzyme rhodanese by reduced nicotinamide adenine dinucleotide.

The enzyme rhodanese (thiosulfate sulfurtransferase; EC 2.8.1.1) is inactivated with a half-time of approximately 3 min when incubated with 50 mM NADH. NAD+, however, has virtually no effect on the activity. Inactivation can be prevented by the inclusion of the substrate thiosulfate. The concentration of thiosulfate giving half-protection is 0.038 mM. In addition, NADH, but not NAD+, is a competitive inhibitor with respect to thiosulfate in the catalyzed reaction (Ki = 8.3 mM). Fluorescence studies are consistent with a time-dependent oxidation of NADH in the presence of rhodanese. The sulfur-free form of rhodanese is more rapidly inactivated than the sulfur-containing form. Spectrophotometric titrations show that inactivation is accompanied by the loss of two free SH groups per enzyme molecule. Inactivation is prevented by the exclusion of air and the inclusion of EDTA (1 mM), and the enzyme activity can be largely protected by incubation with superoxide dismutase or catalase. Rhodanese, inactivated with NADH, can be reactivated by incubation with the substrate thiosulfate (75 mM) for 48 h or more rapidly, but only partially, by incubating with 180 mM dithiothreitol. It is concluded that, in the presence of rhodanese, NADH can be oxidized by molecular oxygen and produce intermediates of oxygen reduction, such as superoxide and/or hydrogen peroxide, that can inactivate the enzyme with consequent formation of an intraprotein disulfide. In addition, NADH, but not NAD+, can reversibly bind to the active site region in competition with thiosulfate. These data are of interest in view of x-ray studies that show structural similarities between rhodanese and nucleotide binding proteins.

Edetic Acid↗

PubMed1977

Cyanide intoxication in sheep: therapeutic value of oxygen or cobalt.

The combination of cobalt salts and oxygen with the traditional sodium nitrite-sodium thiosulfate antidote may have value as cyanide antidotes. Results reported previously in mice were extended to sheep in the present experiments. Cobaltous chloride (15 mg/kg of body weight) or oxygen with or without sodium nitrite and sodium thiosulfate were compared with respect to the median lethal dose of oral sodium cyanide. Although cobaltous chloride or oxygen used alone did result in a significant increase in the median lethal dose of sodium cyanide in sheep, the protection was minor compared with the overall protection provided by the classic antidotal combination of sodium nitrite and sodium thiosulfate. Cobaltous chloride combined with sodium nitrite and sodium thiosulfate did not provide any increase in protection more than that observed with sodium nitrite and sodium thiosulfate alone. Oxygen used in combination with sodium nitrite and sodium thiosulfate did significantly increase the protection. However, the increase in protection was not of sufficient magnitude to recommend it as a practicable addition to the present therapeutic regimen.

Animals↗

PubMed1986

Technetium-sulfur colloid.

The chemistry of the technetium-sulfur colloid produced by the reaction of sodium thiosulfate with acid was investigated. A commercial kit was duplicated, and analyses of elemental sulfur, bisulfite and residual thiosulfate were carried out. The colloidal dispersions were filtered through Nuclepore graded membranes, and the percentages of sulfur and of 99mTc in the various filtrates were determined. In all cases--with varying acid, thiosulfate and time of incubation--there was a rough agreement between the two percentages for particles 0.4 micron in diameter or more. However, for small particles (less than 0.1 micron) there was virtually no sulfur, but there was an appreciable percentage of technetium. It was concluded that the technetium sulfide nuclei formed first, and that the supersaturated sulfur deposited in part on them and in part on its own nuclei. It was found that raising the pH of the preparation to weakly alkaline values and reheating the solution dissolved most of the deposited sulfur by the reaction with sulfite to form thiosulfate, leaving much smaller, virtually sulfur-free technetium sulfide particles. Such a preparation was found to be as efficient as the technetium-antimony sulfide colloid for lymphograms in dogs. Potassium trithionate, K2S3O6, used in place of sodium thiosulfate, produced small Tc-S colloid particles with less sulfur than the conventional thiosulfate-acid system.

Animals↗

PubMed1986

Effect of Sulfur-Containing Compounds on Growth of Methanosarcina barkeri in Defined Medium.

Methanosarcina barkeri Fusaro (DSM 804) could grow on methanol in a mineral medium containing cysteine or thiosulfate as the sole sulfur source. Optimum growth occurred at cysteine concentrations of 1 to 2.8 mM and at thiosulfate concentrations of 2.5 to 5 mM. No inhibition of growth was observed even when these concentrations were doubled in the culture medium. Under the optimum cysteine and thiosulfate concentrations, the generation times of the organism were about 8 to 10 and 10 to 12 h, respectively, giving a cell yield of about 0.14 to 0.17 and 0.08 to 0.11 g (dry weight)/g of methanol consumed. The organism metabolized cysteine and thiosulfate during growth, giving rise to sulfide in the culture medium. H(2)S evolution from cysteine and thiosulfate was catalyzed by two enzymes, namely cysteine desulfhydrase and thiosulfate reductase, respectively, as revealed by enzyme assay in the crude cell-free extract of the organism.

Journal Article↗

PubMed1995

Cyanide antagonism with carrier erythrocytes and organic thiosulfonates.

Previous studies reported that resealed erythrocytes containing rhodanese (CRBC) and NA2S2O3 rapidly metabolize cyanide to the less toxic thiocyanate both in vitro and in vivo. This provided a new conceptual approach to prevent and treat cyanide intoxication. Although the rhodanese-containing carrier cells with thiosulfate as the sulfur donor were efficacious, this approach has potential disadvantages, as thiosulfate has limited penetration of cell membrane and product inhibition of rhodanese can occur due to inorganic sulfite accumulation. In order to circumvent substrate limitation and product inhibition by sodium thiosulfate, organic thiosulfonates were explored. These thiosulfonates have higher lipid solubility than thiosulfate and therefore can replenish the depleted sulfur donor, as they can readily penetrate cell membranes. Also, product inhibition of rhodanese is less apt to occur. This change in sulfur donors should greatly enhance cyanide detoxication, replenish the sulfur donor, and minimize product inhibition of rhodanese. Present studies demonstrate the enhanced efficacy of exogenous organic thiosulfonates over sodium thiosulfate in the CRBC antidotal system to detoxify the lethal effects of cyanide either alone or in combinations with exogenously administered NaNO2. Murine carrier erythrocytes containing purified bovine liver rhodanese were administered intravenously into male Balb/C mice. Subsequently, butanethiosulfonate (BTS) or Na2S2O3 (ip), and NaNO2 (sc) were co-administered prior to KCN (sc). Potency ratios, derived from the LD50 values, were compared in groups of mice treated with CRBC-Na2S2O3 or CRBC-BTS either alone or in combination with NaNO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1976

Reaction of rhodanese with dithiothreitol.

The reaction between bovine rhodanese (thiosulfate:cyanide sulfurtransferase, EC 2.8.1.1) and reduced dithiothreitol has been studied. This reagent, in the absence of thiosulfate, reduces the amount of sulfur carried by rhodanese with formation of sulfide and oxidized dithiothreitol: E-S-SH + reduced dithiothreitol replaced by E-SH + HS- + oxidized dithiothreitol, (E = enzyme). An inactivation was observed at high dithiothreitol/enzyme ratios or at very low enzyme concentrations. The inactivation was not observed in the presence of thiosulfate and can be reversed by cyanide or thiosulfate. A thiosulfate reduction activity of rhodanese was also found using dithiothreitol as reductant.

Animals↗

PubMed1994

Encapsulation of rhodanese and organic thiosulfonates by mouse erythrocytes.

A series of organic thiosulfonates were synthesized and studied as sulfur donor substrates for rhodanese encapsulated within murine carrier erythrocytes. Previous studies have indicated that resealed erythrocytes containing rhodanese (CRBC) and sodium thiosulfate can rapidly metabolize cyanide to the less toxic thiocyanate. This thiosulfate-rhodanese system was very efficacious as a new conceptual approach to antagonize cyanide intoxication both in vitro and in vivo. However, its potential is restricted because of the limited availability of thiosulfate due to its poor permeability through RBC membrane. Present studies suggest that there are advantages in using alternative sulfur donors, i.e., organic thiosulfonates in this rhodanese-containing resealed erythrocyte system, since these compounds have higher lipid solubility than inorganic thiosulfates and can readily penetrate the red blood cell membrane. Therefore, this system could provide a virtually unlimited amount of sulfur donor to the encapsulated rhodanese even if the substrates are in solution outside the cells. Moreover, the rhodanese reaction rate of any of these organic thiosulfonates is much faster than the rate observed with the classic cyanide antidote, sodium thiosulfate. This CRBC system will continue to detoxify cyanide even when these encapsulated sulfur donors are depleted, as the lipid soluble organic thiosulfonate outside the cells will diffuse past the membrane into the cell to replenish the sulfur donor. The encapsulation efficiency for rhodanese is about 30%, and the velocity of the rhodanese reaction increases linearly with the volume of enzyme-laden erythrocytes. Similarly, reaction velocity increases linearly with substrate concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2003

Complete denitrification in coculture of obligately chemolithoautotrophic haloalkaliphilic sulfur-oxidizing bacteria from a hypersaline soda lake.

Eight anaerobic enrichment cultures with thiosulfate as electron donor and nitrate as electron acceptor were inoculated with sediment samples from hypersaline alkaline lakes of Wadi Natrun (Egypt) at pH 10; however, only one of the cultures showed stable growth with complete nitrate reduction to dinitrogen gas. The thiosulfate-oxidizing culture subsequently selected after serial dilution developed in two phases. Initially, nitrate was mostly reduced to nitrite, with a coccoid morphotype prevailing in the culture. During the second stage, nitrite was reduced to dinitrogen gas, accompanied by mass development of thin motile rods. Both morphotypes were isolated in pure culture and identified as representatives of the genus Thioalkalivibrio, which includes obligately autotrophic sulfur-oxidizing haloalkaliphilic species. Nitrate-reducing strain ALEN 2 consisted of large nonmotile coccoid cells that accumulated intracellular sulfur. Its anaerobic growth with thiosulfate, sulfide, or polysulfide as electron donor and nitrate as electron acceptor resulted in the formation of nitrite as the major product. The second isolate, strain ALED, was able to grow anaerobically with thiosulfate as electron donor and nitrite or nitrous oxide (but not nitrate) as electron acceptor. Overall, the action of two different sulfur-oxidizing autotrophs resulted in the complete, thiosulfate-dependent denitrification of nitrate under haloalkaliphilic conditions. This process has not yet been demonstrated for any single species of chemolithoautotrophic sulfur-oxidizing haloalkaliphiles.

Cell Division↗

PubMed2004

Absence or decreased endogenous thiosulfaturia: a cause of recurrent calcium nephrolithiasis.

In two earlier publications we reported excellent therapeutic results in patients with recurrent calcium nephrolithiasis, using oral or intravenous i.v. sodium thiosulfate on the one hand, and on treatment of tumorus-soft periarticular tissues calcifications on the other. Thus, we considered useful to measure endogenous thiosulfaturia, using a specific HPLC method, in 25 healthy adult males and 25 patients with recurrent calcium nephrolithiasis. Healthy adult males excreted between 11 and 16 microM/24 hour of endogenous thiosulfate, while patients with recurrent calcium nephrolithiasis excreted significantly lower amounts of 6 and 10 microM/24 hour, except one patient, who did not excrete endogenous thiosulfate, reflecting probably a genetic abnormality. Thiosulfate is a unique agent for treatment of recurrent calcium nephrolithiasis as well as some other abnormal calcium depositions. Two doses of 5 mM sodium thiosulfate daily are therapeutically sufficient.

Adult↗

PubMed1982

Oxidation-reduction potentials of respiratory chain components in Thiobacillus A2.

(1) Cells of Thiobacillus A2 grown chemoautotrophically on thiosulfate or heterotrophically on succinate with oxygen contained b-, c-, o-, a- and a3-type cytochromes. The amount of cytochrome per mg of cell protein was much greater in thiosulfate-grown cells and differences in the relative concentrations of cytochromes were observed for the different growth conditions. (2) The half-reduction potentials at pH 7.0 (Em,7.0) and spectral maxima of c-, b-, a- and a3-type cytochromes were similar in cells grown aerobically with thiosulfate or with succinate as the growth substrate. (3) The half-reduction potential of the 'invisible', or high-potential copper, as determined from the potentiometric behavior of the carbon monoxide-reduced cytochrome a3 complex at pH 8.0, was 365 mV. (4) Reducing equivalents from thiosulfate appear to enter the respiratory chain at the cytochrome c level; however, studies in cell-free extracts were limited due to a loss in respiratory activity with thiosulfate as a substrate upon cell disruption.

Carbon Monoxide↗

PubMed1986

The efficacy of alpha-ketoglutaric acid in the antagonism of cyanide intoxication.

It has been reported that compounds containing carbonyl groups can readily react with cyanide. Pyruvic acid, an alpha-ketocarboxylic acid, has been shown to antagonize the lethal effects of cyanide. It is suggested that its mechanism of action rests in its ability to react with or "bind" cyanide. In this study, alpha-ketoglutaric acid, also an alpha-ketocarboxylic acid, was evaluated for its ability to counteract the lethal effects of cyanide. alpha-Ketoglutaric acid increased the LD50 value of cyanide (6.7 mg/kg) by a factor of five, a value statistically equivalent to that ascertained in mice pretreated with sodium thiosulfate and sodium nitrite. The combination of alpha-ketoglutaric acid and sodium thiosulfate increased the LD50 value of cyanide to 101 mg/kg. Addition of sodium nitrite to the alpha-ketoglutaric acid/sodium thiosulfate regimen increased the LD50 value of cyanide to 119 mg/kg. Unlike sodium nitrite, no induction of methemoglobin formation was observed with alpha-ketoglutaric acid pretreatment. It is apparent from these studies that the administration of alpha-ketoglutaric acid in conjunction with sodium thiosulfate resulted in fewer animal deaths than sodium nitrite and sodium thiosulfate without the dangerous formation of methemoglobin.

Animals↗

PubMed1998

The glutathione dependence of inorganic sulfate formation from L- or D-cysteine in isolated rat hepatocytes.

The GSH dependence of the metabolic pathways involved in the conversion of cysteine to sulfate in intact cells has been investigated. It was found that hepatocyte-catalysed sulfate formation from added L-cysteine did not occur if hepatocyte GSH was depleted beforehand, but was restored when GSH levels recovered. Furthermore, sulfate formation did not recover in GSH-depleted hepatocytes if GSH synthesis was prevented with buthionine sulfoximine. Thiosulfate formation was, however, markedly enhanced in GSH-depleted hepatocytes. These results suggest that thiosulfate is an intermediate in the formation of inorganic sulfate from L-cysteine and that GSH was required for the conversion of thiosulfate to inorganic sulfate. Much less sulfate was formed if the cysteine was replaced with cysteinesulfinate. Furthermore, sulfate formation from L-cysteine was markedly inhibited by the addition of the transaminase inhibitor DL-cycloserine or the gamma-cystathionase inhibitor DL-propargylglycine. The major routes of sulfate formation from L-cysteine therefore seems to involve pathways that do not involve L-cysteinesulfinate. Similar amounts of sulfate were formed from D-cysteine as L-cysteine. Thiosulfate instead of sulfate was also formed in GSH-depleted hepatocytes. However, sulfate formation from D-cysteine differed from L-cysteine in that it was inhibited by the D-aminoacid oxidase inhibitor sodium benzoate and was not affected by transaminase or gamma-cystathionase inhibitors. These results suggest that thiosulfate is an intermediate in sulfate formation from D-cysteine and involves the oxidation of D-cysteine by D-amino acid oxidase to form beta-mercaptopyruvate.

Alkynes↗

PubMed1978

Dissimilatory reduction of bisulfite by Desulfovibrio vulgaris.

The reduction of bisulfite by Desulfovibrio vulgaris was investigated. Crude extracts reduced bisulfite to sulfide without the formation (detection) of any intermediates such as trithionate or thiosulfate. When the particulate fractions was removed from crude extracts by high-speed centrifugation, the soluble supernatant fraction reduced bisulfite sequentially to trithionate, thiosulfate, and sulfide. Addition of particles or purified membranes to the soluble fraction restored the original activity demonstrated by crude extracts, i.e., reduction of bisulfite to sulfide without the formation of trithionate and/or thiosulfate. By using antiserum directed against bisulfite reductase, the reduction of bisulfite by crude extracts was inhibited. This finding, in addition to several recycling studies of thiosulfate reduction, provided evidence that bisulfite reduction by D. vulgaris operated through the pathway involving trithionate and thiosulfate as intermediates. The role of membranes in this process is discussed.

Desulfovibrio↗

PubMed1981

Assimilatory sulfur metabolism in marine microorganisms: a novel sulfate transport system in Alteromonas luteo-violaceus.

The sulfate transport mechanism of a marine bacterium, Alteromonas luteo-violaceus, was unique among microorganisms in its extremely low affinity for the sulfate analog thiosulfate. Distinguishing characteristics included weak inhibition of sulfate transport by thiosulfate, inability to transport thiosulfate effectively, poor growth using thiosulfate as the sole source of sulfur, and a mild effect of the sulfhydryl reagent para-hydroxymercuribenzoate. In contrast, sulfate transport by a marine pseudomonad, Pseudomonas halodurans, was strongly inhibited by thiosulfate, and para-hydroxymercuribenzoate reversibly but completely blocked sulfate transport.

Bacteria↗