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PubMed1987

Domain structural flexibility in rhodanese examined by quenching of a phosphorescent probe.

Rhodanese (thiosulfate:cyanide sulfurtransferase, EC 2.8.1.1) is an enzyme composed of two domains with the catalytic site located in the bottom of the crevice formed by the two domains. In this work, rhodanese was labeled at its catalytic site with the phosphorescence probe eosin isothiocyanide. The accessibility of molecules to the probe was determined by phosphorescence lifetime-quenching studies. The phosphorescent probe was much more accessible to small molecules (I- and thiosulfate, radius about 3-5 A) than to a larger molecule (spin-label probe TEMPO, radius about 8-10 A). It was observed that a temperature-induced change in the rate of quenching occurred at around 28 degrees C. The results are interpreted in terms of structural fluctuations and displacement in the domains.

Animals↗

PubMed1992

Recombinant bovine rhodanese: purification and comparison with bovine liver rhodanese.

Recombinant bovine rhodanese (thiosulfate: cyanide sulfurtransferase, EC 2.8.1.1) has been purified to homogeneity from Escherichia coli BL21(DE3) by cation-exchange chromatography. Recombinant and bovine liver rhodanese coelectrophorese under denaturing conditions, with an apparent subunit molecular weight of 33,000. The amino terminal seven residues of the recombinant protein are identical to those of the bovine enzyme, indicating that E. coli also removes the N-terminal methionine. The Km for thiosulfate is the same for the two proteins. The specific activity of the recombinant enzyme is 12% higher (816 IU/mg) than that of the bovine enzyme (730 IU/mg). The two proteins are indistinguishable as to their ultraviolet absorbance and their intrinsic fluorescence. The ability of the two proteins to refold from 8 M urea to enzymatically active species was similar both for unassisted refolding, and when folding was assisted either by the detergent, lauryl maltoside or by the E. coli chaperonin system composed of cpn60 and cpn10. Bovine rhodanese is known to have multiple electrophoretic forms under native conditions. In contrast, the recombinant protein has only one form, which comigrates with the least negatively charged of the bovine liver isoforms. This is consistent with the retention of the carboxy terminal residues in the recombinant protein that are frequently removed from the bovine liver protein.

Animals↗

PubMed1984

Cerebral cytochrome a,a3 inhibition by cyanide in bloodless rats.

Brain cytochrome a,a3 inhibition is presumed to be the site of lethal histotoxic hypoxia in cyanide poisoning perhaps because of the relative inability of the brain to metabolize cyanide. However, only limited data are available about cyanide toxic effects and possible antagonism in the in vivo brain. In this study, in situ, multiple wavelength, spectrophotometric monitoring of brain cytochrome a,a3 was used to observe oxidation-reduction (redox) responses of cerebral cytochrome a,a3 to intravenous potassium cyanide administration. Bloodless rats prepared by perfluorochemical emulsion (FC-43) exchange transfusion allowed monitoring of cyanide-cytochrome a,a3 interaction without spectral interference by hemoglobin. We found that cyanide-induced transient increases in cytochrome a,a3 reduction level and subsequent redox recovery kinetics were similar in bloodless and normal blood circulated rats. Electroencephalographic activity was maintained until a 50% increase in the reduction level of cytochrome a,a3 was induced with cyanide. Pre-treatment with the cyanide antagonist sodium thiosulfate also protected brain cytochrome a,a3 from cyanide-mediated redox state changes by approximately 4-fold both in normal blood circulated controls and during FC-43 circulation. These latter results indicate that sodium thiosulfate, presumably acting at tissue sites of rhodanese activity, can prevent cerebral cytochrome a,a3 reduction by cyanide even in the virtual absence of blood or circulating proteins.

Animals↗

PubMed1991

Severe cyanide poisoning from the ingestion of an acetonitrile-containing cosmetic.

A 39-year-old woman ingested 59 mL of Super Nail Nail Off (American International Industries, Hollywood, CA) (containing 99% acetonitrile) in a suicide attempt. Following a latent period of approximately 12 hours, the patient developed cyanide poisoning with severe metabolic acidosis, seizures, and shallow respirations. She responded to the administration of sodium nitrite and sodium thiosulfate, although the administration of nitrite produced bradycardia and hypotension. She developed several relapses over the course of her hospitalization and each time responded to sodium thiosulfate administration. The patient developed hypernatremia from the sodium load given to her; hemodialysis and charcoal hemoperfusion were initiated to correct the hypernatremia and to attempt to remove cyanide, thiocyanate, and acetonitrile. On the fifth hospital day, the patient was fully recovered and was discharged.

Acetonitriles↗

PubMedDate not supplied

Cyanide poisoning from propionitrile exposure.

A 55-year-old worker was exposed to propionitrile by both the inhalational and dermal routes. He rapidly lost consciousness and developed metabolic acidosis consistent with cyanide poisoning. Treatment with hydroxycobalamin and sodium thiosulfate produced complete symptom resolution within an hour. Serial blood cyanide and thiocyanate levels documented a rapid decrease in cyanide and concomitant increase in thiocyanate. Serious cyanide poisoning can occur from propionitrile exposure. Treatment with hydroxycobalamin and sodium thiosulfate can produce rapid clinical improvement.

Cyanides↗

PubMed2005

Making chlorine greener: performance of alternative dechlorination agents in wastewater.

The residual chlorine in chlorine-disinfected and dechlorinated wastewater was characterized using a liquid chromatograph that was switched between reversed-phase separation and flow injection analysis modes, permitting measurement of fractionated and total residual chlorine, respectively. Residuals were detected in the effluent of an operating wastewater treatment plant employing chlorine disinfection and sulfite dechlorination. Despite dechlorination, an estimated total residual chlorine of 3 microM (0.2 ppm as Cl2) was detected in the effluent. To improve dechlorination effectiveness, four alternative agents (ascorbic acid, iron, sulfite plus iodide mediator, thiosulfate) were compared to sulfite on laboratory-chlorinated wastewater. Listed in order of decreasing relative effectiveness, we found: iron metal >> sulfite plus iodide approximately = thiosulfate > sulfite >> ascorbic acid. Only the iron metal column was completely effective at rapidly removing all traces of residual chlorine.

Ascorbic Acid↗

PubMed2005

Cyanide detoxification by recombinant bacterial rhodanese.

Cyanide is a major environmental pollutant of the chemical and metallurgical industries. Although extremely toxic, cyanide can enzymatically be converted to the less toxic thiocyanate by rhodaneses (thiosulfate:cyanide sulfurtransferases, EC 2.8.1.1). We engineered a genetic system to express high levels of recombinant Pseudomonas aeruginosa rhodanese (r-RhdA) in Escherichia coli, and used this organism to test the role of r-RhdA in cyanide detoxification. Inducible expression of the rhdA gene under the control of the hybrid T7-lacO promoter yielded active r-RhdA over a 4-h period, though r-RhdA-expressing E. coli showed decreased viability starting from 1 h post-induction. At this time, Western blot analysis and enzymatic assay showed r-RhdA partition between the cytoplasm (95%) and the periplasm (5%). The accessibility of thiosulfate to r-RhdA was a limiting step for the sulfur transfer reaction in the cellular system, but cyanide conversion to thiocyanate could be increased upon permeabilization of the bacterial membrane. Specific r-RhdA activity was higher in the whole-cell assay than in the in vitro assay with pure enzyme (2154 vs. 816 micromol min-1 mg-1 r-RhdA, respectively), likely reflecting enzyme stability. The r-RhdA-dependent cyanide detoxification resulted in increased resistance of r-RhdA overexpressing E. coli to 5 mM cyanide. Bacterial survival was paralleled by release of thiocyanate into the medium. Our results indicate that cyanide detoxification by engineered E. coli cells is feasible under laboratory conditions, and suggest that microbial rhodaneses may contribute to cyanide transformation in natural environments.

Biodegradation, Environmental↗

PubMed2005

Halothiobacillus neapolitanus strain OSWA isolated from "The Old Sulphur Well" at Harrogate (Yorkshire, England).

The "Old Sulphur Well" has a subterranean input of water containing 5.5mM total sulfide, which would be inhibitory to the growth of most bacteria. The obligately chemolithoautotrophic Halothiobacillus neapolitanus is a sulfur bacterium known to tolerate and metabolize high sulfide concentrations, and we report the isolation of H. neapolitanus strain OSWA from this source. Strain OSWA grows well on thiosulfate and tetrathionate as energy sources, and tolerates at least 5mM sulfide. Its specific growth rates and yields in batch culture were 0.22h(-1) and 5.3 gmol(-1) (thiosulfate), and 0.23 h(-1) and 9.5 gmol(-1) (tetrathionate). Its 16S rRNA gene sequence shows >99% identity to reference sequences of H. neapolitanus, and it shares morphological and physiological characteristics typical of the species. It is one of a very small number of strains of H. neapolitanus described to date, and the first to be isolated from an ancient sulfide-rich natural spa.

Culture Media↗

PubMed2005

Kinetics of cyanogen chloride destruction by chemical reduction methods.

In this study, membrane introduction mass spectrometry (MIMS) was applied to evaluate the kinetics of cyanogen chloride (ClCN) destruction by chemical reduction methods, using thiosulfate, sulfite, metabisulfite, ferrous ions and zero-valent iron at various concentrations and pH. The ClCN destruction followed second-order reaction kinetics in all cases of using sulfur compounds, though the second-order rate constants varied substantially from approximately 0.3-25.7 M(-1)s(-1) under different experimental conditions. The destruction of ClCN was primarily attributable to the chemical reduction pathway. Hydroxide-assisted ClCN hydrolysis was only significant at pH 9 and also when the observed reduction rate was relatively slow. The second-order rate constants achieved by sulfur(IV) compounds in the form of sulfite were found to be higher than those obtained with thiosulfate and S(IV) compounds in the form of bisulfite. Ferrous ions and zero-valent iron demonstrated slow or no ClCN reduction up to dosages of 1000 mgL(-1) and 100 gL(-1), respectively. These findings suggest that applying moderately high dosages of S(IV) compounds under neutral or alkali conditions with sufficient contact time is required for wastewater ClCN destruction. In addition, ClCN losses during long-term preservation with excess reducing sulfur compounds prior to analysis can be substantial and should be avoided.

Cyanides↗

PubMed1994

A targeted supradose cisplatin chemoradiation protocol for advanced head and neck cancer.

BACKGROUND: Hypothesizing that cisplatin (DDP) drug resistance is dose dependent and the radiosensitizing effect of DDP is clinically beneficial, we conducted a chemoradiation protocol using extremely high doses of DDP delivered intra-arterially (IA) to locally advanced head and neck tumors. PATIENTS AND METHODS: Twenty-nine patients with untreated stage IV disease received 4 weekly infusions of 150 mg/m2, simultaneous systemic DDP neutralization with intravenous (IV) bolus sodium thiosulfate, and concomitant radiotherapy (180 to 200 cGy/day x 35 fractions). RESULTS: The complete response rate of the 24 evaluable patients as determined with repeat biopsies was 23/24 (96%). Of the 29 patients evaluable for toxicity, central nervous system complications related to the infusion technique occurred with 2/110 infusions, both of which were reversible. The rate of grade III to IV chemotoxicity was 13%. The median length of follow-up was 22 months. There have been 6 recurrences: 1 local; 3 regional; and 2 at distant sites. The projected overall and disease-free 3-year survival was 88% and 53%, respectively. CONCLUSION: We conclude that the combination of rapid selective delivery of supradose DDP/IV thiosulfate neutralization and concomitant radiotherapy can be safely and effectively applied to patients with advanced head and neck cancer. Preliminary survival analysis indicates that this approach may improve the prognosis for patients with an otherwise devastating disease.

Adult↗

PubMed2000

Mutagenic analysis of Thr-232 in rhodanese from Azotobacter vinelandii highlighted the differences of this prokaryotic enzyme from the known sulfurtransferases.

Azotobacter vinelandii RhdA uses thiosulfate as the only sulfur donor in vitro, and this apparent selectivity seems to be a unique property among the characterized sulfurtransferases. To investigate the basis of substrate recognition in RhdA, we replaced Thr-232 with either Ala or Lys. Thr-232 was the target of this study since the corresponding Lys-249 in bovine rhodanese has been identified as necessary for catalytic sulfur transfer, and replacement of Lys-249 with Ala fully inactivates bovine rhodanese. Both T232K and T232A mutants of RhdA showed significant increase in thiosulfate-cyanide sulfurtransferase activity, and no detectable activity in the presence of 3-mercaptopyruvate as the sulfur donor substrate. Fluorescence measurements showed that wild-type and mutant RhdAs were overexpressed in the persulfurated form, thus conferring to this enzyme the potential of a persulfide sulfur donor compound. RhdA contains a unique sequence stretch around the catalytic cysteine, and the data here presented suggest a possible divergent physiological function of A. vinelandii sulfurtransferase.

Animals↗

PubMed2003

Inhibition study of rhodanese by means of electrophoretically mediated microanalysis.

A combination of the electrophoretically mediated microanalysis methodology with a partial filling technique was applied for the inhibition study of bovine liver rhodanese by 2-oxoglutarate. In this set-up, part of the capillary is filled with the best buffer for the enzymatic reaction, while the rest of the capillary is filled with the optimal background electrolyte for separation of substrates and products. The estimated value of K1 for 2-oxoglutarate was 3.62 x 10(-4) +/- 1.43 x 10(-4) M with respect to cyanide and 1.40 x 10(-3) +/- 1.60 x 10(-4) M with respect to thiosulfate. In addition, the type of inhibition was also evaluated. The findings of 2-oxoglutarate as the competitive inhibitor with respect to cyanide and as the uncompetitive inhibitor with respect to thiosulfate are in accordance with previous literature data.

Electrophoresis↗

PubMed2003

Optimal methods for quenching H2O2 residuals prior to UFC testing.

In this paper, the quenching of hydrogen peroxide by catalase, sodium hypochlorite, sodium thiosulfate and sodium sulfite, prior to UFC testing, was investigated. Sodium hypochlorite, sodium thiosulfate and sodium sulfite were found to be unsuitable for quenching H2O2 residuals because the procedures are time-consuming and complicated in that they require potentially multiple measurements of the peroxide and chlorine residuals. In contrast, quenching of peroxide with catalase is a simple procedure. Catalase doses of less than 0.2 mg/L were found to have no impact on DBP (TTHM, HAA and aldehyde) formation in the UFC test, and the time that was needed to quench 100 mg/L peroxide (room temperature, pH 8.3) was less than 10 min. In addition, peroxide was found to react with DPD reagents that are used to measure chlorine residuals, a phenomenon that may lead to falsely high chlorine residuals in the UFC test.

Catalase↗

PubMed1997

Identification of a functional homolog of the Escherichia coli and Salmonella typhimurium cysM gene encoding O-acetylserine sulfhydrylase B in Campylobacter jejuni.

The final step of L-cysteine biosynthesis in Escherichia coli and Salmonella typhimurium consists of the formation of L-cysteine from O-acetylserine and sulfide. This reaction can be catalyzed by two enzymes, O-acetylserine sulfhydrylase A and O-acetylserine sulfhydrylase B, the former of which has been more rigorously characterized. In contrast to O-acetylserine sulfhydrylase A, O-acetylserine sulfhydrylase B is preferentially used for cysteine biosynthesis during anaerobic growth and is able to utilize thiosulfate as a substrate. Campylobacter jejuni is a micro-aerophilic, Gram-negative bacterium, and a member of the epsilon subdivision of eubacteria. We have cloned, sequenced, and expressed a gene from C. jejuni that encodes a protein of 299 aa with a calculated molecular mass of 32,367 Da. Complementation analysis of an E. coli cysteine auxotroph with the pMEK34-14 recombinant plasmid containing a 1.2-kb insert of chromosomal DNA from C. jejuni revealed that transformants were capable of growth in medium containing either sulfide or thiosulfate as sole sulfur sources. These data indicate that the cloned C. jejuni gene is a functional homolog of the cysM gene that codes for O-acetylserine sulfhydrylase B in E. coli and S. typhimurium.

Amino Acid Sequence↗

PubMed2002

Planktonic nitrate-reducing bacteria and sulfate-reducing bacteria in some western Canadian oil field waters.

Oil fields that use water flooding to enhance oil recovery may become sour because of the production of H(2)S from the reduction of sulfate by sulfate-reducing bacteria (SRB). The addition of nitrate to produced waters can stimulate the activities of nitrate-reducing bacteria (NRB) and control sulfide production. Many previous studies have focused on chemolithotrophic bacteria that can use thiosulfate or sulfide as energy sources while reducing nitrate. Little attention has been given to heterotrophic NRB in oil field waters. Three different media were used in this study to enumerate various types of planktonic NRB present in waters from five oil fields in western Canada. The numbers of planktonic SRB and bacteria capable of growth under aerobic conditions were also determined. In general, microbial numbers in the produced waters were very low (<10 ml x (-1)) in samples taken near or at wellheads. However, the numbers increased in the aboveground facilities. No thiosulfate-oxidizing NRB were detected in the oil field waters, but other types of NRB were detected in 16 of 18 produced water samples. The numbers of heterotrophic NRB were equal to or greater than the number of sulfide-oxidizing, chemolithotrophic NRB in 12 of 15 samples. These results showed that each of the oil fields contained NRB, which might be stimulated by nitrate amendment to control H(2)S production by SRB.

Animals↗

PubMed2000

Plant mercaptopyruvate sulfurtransferases: molecular cloning, subcellular localization and enzymatic activities.

Mercaptopyruvate sulfurtransferase (MST, EC 2.8.1.2) and thiosulfate sulfurtransferase (TST, rhodanese, EC 2.8.1.1) are evolutionarily related enzymes that catalyze the transfer of sulfur ions from mercaptopyruvate and thiosulfate, respectively, to cyanide ions. We have isolated and characterized two cDNAs, AtMST1 and AtMST2, that are Arabidopsis homologs of TST and MST from other organisms. Deduced amino-acid sequences showed similarity to each other, although MST1 has a N-terminal extension of 57 amino acids containing a targeting sequence. MST1 and MST2 are located in mitochondria and cytoplasm, respectively, as shown by immunoblot analysis of subcellular fractions and by green fluorescent protein (GFP) analysis. However, some regions of MST1 fused to GFP were found to target not only mitochondria, but also chloroplasts, suggesting that the regions on the targeting sequence recognized by protein import systems of mitochondria and chloroplasts are not identical. Recombinant proteins, expressed in Escherichia coli, exhibited MST/TST activity ratios determined from kcat/Km values of 11 and 26 for MST1 and MST2, respectively. This indicates that the proteins encoded by both AtMST1 and AtMST2 are MST rather than TST type. One of the hypotheses proposed so far for the physiological function of MST and TST concerns iron-sulfur cluster assembly. In order to address this possibility, a T-DNA insertion Arabidopsis mutant, in which the AtMST1 was disrupted, was isolated by PCR screening of T-DNA mutant libraries. However, the mutation had no effect on levels of iron-sulfur enzyme activities, suggesting that MST1 is not directly involved in iron-sulfur cluster assembly.

Amino Acid Sequence↗

PubMed1999

Prevalence of gold sensitivity in asymptomatic individuals with gold dental restorations.

BACKGROUND: The clinical relevance of positive patch test reactions to gold sodium thiosulfate in asymptomatic individuals with gold dental restorations is often unclear. Knowledge of the prevalence of gold sensitivity in individuals with and without gold dental restorations is required to better understand the relevance of these reactions. OBJECTIVE: To determine the prevalence of positive patch test reactions to gold in asymptomatic individuals with gold dental restorations (gold patients) compared with similar individuals without gold dental appliances (nongold patients). METHODS: One hundred thirty-six healthy, asymptomatic patients were patch tested to gold sodium thiosulfate, nickel sulfate and palladium chloride. Readings occurred after 2 days and 7 days. RESULTS: Of the patients tested, 24 of 71 (33.8%) gold patients had a positive reaction to gold versus 7 of 65 (10.8%) of the nongold patients, P <.001. Of those with a positive gold reaction, 12 of 31 (38.7%) also had a positive nickel reaction. Nickel alone was positive in 18 of 71 (25. 4%) of gold patients versus 11 of 65 (16.9%) of nongold patients. 19 of 29 (65.5%) of those with a positive nickel reaction also reacted to palladium and 19 of 22 (86.4%) of those with a palladium reaction also reacted to nickel. The rate of allergy to gold computed over a 3-year period for patients patch tested in the Oregon Health Sciences University (OHSU) Contact Dermatitis Clinic was 13.5% (46/342). CONCLUSIONS: The prevalence of gold sensitivity in individuals with gold dental restorations is approximately 33.8%. This is significantly greater than the 10.8% prevalence seen in individuals without gold dental appliances, as well as greater than the 3-year rate from the OHSU Contact Dermatitis Clinic. This data should help shed light on issues of clinical relevance.

Adult↗

PubMed2003

The crystal structure of Leishmania major 3-mercaptopyruvate sulfurtransferase. A three-domain architecture with a serine protease-like triad at the active site.

Leishmania major 3-mercaptopyruvate sulfurtransferase is a crescent-shaped molecule comprising three domains. The N-terminal and central domains are similar to the thiosulfate sulfurtransferase rhodanese and create the active site containing a persulfurated catalytic cysteine (Cys-253) and an inhibitory sulfite coordinated by Arg-74 and Arg-185. A serine protease-like triad, comprising Asp-61, His-75, and Ser-255, is near Cys-253 and represents a conserved feature that distinguishes 3-mercaptopyruvate sulfurtransferases from thiosulfate sulfurtransferases. During catalysis, Ser-255 may polarize the carbonyl group of 3-mercaptopyruvate to assist thiophilic attack, whereas Arg-74 and Arg-185 bind the carboxylate group. The enzyme hydrolyzes benzoyl-Arg-p-nitroanilide, an activity that is sensitive to the presence of the serine protease inhibitor N alpha-p-tosyl-L-lysine chloromethyl ketone, which also lowers 3-mercaptopyruvate sulfurtransferase activity, presumably by interference with the contribution of Ser-255. The L. major 3-mercaptopyruvate sulfurtransferase is unusual with an 80-amino acid C-terminal domain, bearing remarkable structural similarity to the FK506-binding protein class of peptidylprolyl cis/trans-isomerase. This domain may be involved in mediating protein folding and sulfurtransferase-protein interactions.

Amino Acid Sequence↗