Distribution of rhodanese in tissues of goat (Capra hircus)

Rhodanese (thiosulfate: cyanide sulfurtransferase, EC. 2.8.1.1) is a ubiquitous enzyme present in all living organisms, from bacteria to humans and plays a central role in cyanide detoxification. The purpose of this investigation is to determine and compare rhodanese activity in different tissues of adult male and female goats (Capra hircus). The results showed that the specific activity of rhodanese in different tissues was significantly different (P<0.05). The highest activity of rhodanese was in epithelium of rumen, followed by epithelia of reticulum and omasum and liver. No significant difference was observed when tissues of male and female goats were compared. The lowest specific activity of rhodanese was observed in spleen, urinary bladder, lymph node, ovary, skeletal muscle and pyloric muscle of abomasum. The results of this study may indicate the involvement of rhodanese in cyanide detoxification in goat tissues that have greater potential to be exposed to higher levels of cyanide.     

Identification of Thiobacillus ferrooxidans strains based on restriction fragment length polymorphism analysis of 16S rDNA.

The 16S rDNA sequences from ten strains of Thiobacillus ferrooxidans were amplified by PCR. The products were compared by performing restriction fragment length polymorphism (RFLP) analysis with restriction endonucleases Alu I, Hap II, Hha I, and Hae III. The RFLP patterns revealed that T. ferrooxidans could be distinguished from other iron- or sulphur-oxidizing bacteria such as T. thiooxidans NB1-3, T. caldus GO-1, Leptospirillum ferrooxidans and the marine iron-oxidizing bacterium strain KU2-11. The RFLP patterns obtained with Alu I, Hap II, and Hae III were the same for nine strains of T. ferrooxidans except for strain ATCC 13661. The RFLP patterns for strains NASF-1 and ATCC 13661 with Hha I were distinct from those for other T. ferrooxidans strains. The 16S rDNA sequence of T. ferrooxidans NASF-1 possessed an additional restriction site for Hha I. These results show that iron-oxidizing bacteria isolated from natural environments were rapidly identified as T. ferrooxidans by the method combining RFLP analysis with physiological analysis.     

Activation of bovine plasminogen by Streptococcus uberis

Abstract Thiosulfate and tetrathionate oxidation activity of Thiobacillus ferrooxidans were found to be absent in iron-growth cell as well as in the cells grown anaerobically on elemental sulfur. While the thiosulfate oxidase activity was absent in the cell-free extract of the above cells, the activity of rhodanese was present irrespective of the culture condition of T. ferrooxidans . It is thus conceivable that rhodanese is not involved in thiosulfate metabolism. During growth in presence of ferrous sulfate plus elemental sulfur, the thiosulfate/tetrathionate oxidation activity was absent till the oxidation of ferrous iron was complete and the cells harvested only in the latter period acquired the thiosulfate/tetrathionate oxidation activity. Thus it becomes evident that the inhibition of thiosulfate and tetrathionate oxidation is solely due to presence of ferrous iron.     

Rhodanese from Thiobacillus A2: catalysis of reactions of thiosulphate with dihydrolipoate and dihydrolipoamide.

Rhodanese (thiosulphate:cyanide sulphurtransferase EC.2.8.1.1) was purified 25- to 30-fold from thiosulphate-grown Thiobacillus A2. It exhibited a pH optimum between pH 10-2 and 10-4 and apparent Km values of 0-36 mM-Na2S2O3 and 17 mM-KCN. Ultraviolet spectrophotometry and thin-layer chromatography showed that the enzyme catalysed the reaction of S2O3(2-) with dihydrolipoic acid or dihydrolipoamide, producing alpha-lipoate or lipoamide, with the intermediate production of the persulphides of dihydrolipoate and dihydrolipoamide, which were demonstrated chromatographically. This is the first demonstration of catalysis by a thiobacillus rhodanese of reactions which are likely to be physiologically important in the oxidative dissimilation of thiosulphate by a central energy-conserving pathway.     

Regional and Subcellular Distribution of Cyanide Metabolizing Enzymes in the Central Nervous System

Activities of cyanide metabolizing enzymes were measured in various subcellular fractions and regions in the central nervous system. Brain rhodanese and liver beta-mercaptopyruvate sulfurtransferase showed a slight decrease in activity after death. The activity of beta-mercaptopyruvate sulfurtransferase was negligible in the rat brain, compared with that of rhodanese. A small amount of thiocyanate was produced from cyanide and beta-mercaptopyruvate in the human brain, probably due to contamination with red blood cells. Rhodanese activity was widely distributed in all the areas of nervous tissue examined. In the rat the olfactory bulb showed the highest rhodanese activity, and high activity was also observed served in the thalamus, septum, hippocampus, and dorsal part of the midbrain. Rhodanese activity was low in various parts of the cerebral cortex. The distribution pattern of rhodanese in post-mortem human brain was essentially similar to that in rat brain. The thalamus, amygdala, centrum semiovale, colliculus superior, and cerebellar cortex showed high rhodanese activity in the human brain. Rhodanese activity was detected in the spinal cord. Anterior horn showed the highest rhodanese activity in the cervical, thoracic, and lumbar cord. Most rhodanese activity in the rat brain was recovered in the mitochondrial fraction with the highest specific activity. Rhodanese activity was lower in spinal cords obtained from autopsied cases with amyotrophic lateral sclerosis than in those of control subjects. A significant decrease in rhodanese was observed in the posterior column of the cervical or thoracic cord, but the activity in the anterior horn did not differ significantly between the two groups.     

Mercuric reductase enzyme from a mercury-volatilizing strain of Thiobacillus ferrooxidans.

Cell-free mercury volatilization activity (mercuric reductase) was obtained from a mercury-volatilizing Thiobacillus ferrooxidans strain, and the properties of intact-cell and cell-free activities were compared with those determined by plasmid R100 in Escherichia coli. Intact cells of T. ferrooxidans volatilized mercury at pH 2.5, whereas cells of E. coli did not. Cell-free enzyme preparations from both bacteria functioned best at or above neutral pH and not at all at pH 2.5. The T. ferrooxidans mercuric reductase was a soluble enzyme that was dependent upon added NAD(P)H. The enzyme activity was stable at 80 degrees C, required an added thiol compound, and was stimulated by EDTA. Antisera against purified mercuric reductases from transposon Tn501 and plasmid R831 (which inactivated mercuric reductases from a wide range of enteric and pseudomonad strains) did not inactivate the enzyme from T. ferrooxidans.     

NADH: Nitrate reductase activity restoration by rhodanese

The NADH: nitrate reductase from durum wheat leaves was inactivated by cyanide and its activity restored by thiosulphate and beef kidney rhodanese. Rhodanese and thiosulphate, added to NADH-nitrate reductase before cyanide treatment protected NADH-nitrate reductase activity. No oxidizing agent was required for the protection or restoration of cyanide treated NADH-nitrate reductase.     

Optimal conditions for bio-oxidation of ferrous ions to ferric ions using Thiobacillus ferrooxidans

A chemo-biochemical process using Thiobacillus ferrooxidans for desulphurization of gaseous fuels and emissions containing hydrogen sulphide (H2S) has been developed. In the first stage, H2S present in fuel gas and emissions is selectively oxidized to elemental sulphur using ferric sulphate. The ferrous sulphate produced in the first stage of the process is oxidized to ferric sulphate using Thiobacillus ferrooxidans for recycle and reuse in the process. The effects of process variables, temperature, pH, total dissolved solids (TDS), elemental sulphur, ferric and magnesium ions on bio-oxidation of ferrous ions to ferric ions were investigated using flask culture experiments. The bio-oxidation of ferrous ions to ferric ions could be achieved efficiently in the temperature range of 20(+/-1)-44(+/-1) degrees C. A pH range of 1.8(+/-0.02)-2.2(+/-0.02) was optimum for the growth of culture and effective bio-oxidation of ferrous ions to ferric ions. The effect of TDS on bio-oxidation of ferrous ions indicated that a preacclimatized culture in a growth medium containing high dissolved solid was required to achieve effective bio-oxidation of ferrous ions. Elemental sulphur ranging from 1000 to 100,000 mg/l did not have any effect on efficiency of ferrous ion oxidation. The efficiency of bio-oxidation of ferrous ions to ferric ions was not affected in the presence of ferric ions up to a concentration of 500 mg/l while 3 mg/l of magnesium ion was optimal for achieving effective bio-oxidation.     

Immunohistochemical localization of rhodanese

Summary The role of rhodanese in the detoxication of acute cyanide exposure is controversial. The debate involves questions of the availability of rhodanese to cyanide in the peripheral circulation. Blood-borne cyanide will distribute to the brain and may induce lesions or even death. The present study addresses the dispute by determining the distribution of rhodanese in tissues considered to have the highest rhodanese activity and thought to serve as major detoxication sites. The results indicate that rhodanese levels are highest in (1) hepatocytes that are in close proximity to the blood supply of the liver (2) epithelial cells surrounding the bronchioles (a major entry route for gaseous cyanide) and (3) proximal tubule cells of the kidney (serving to facilitate cyanide detoxication and elimination as thiocyanate). Rhodanese activity in the brain is low compared with liver and kidney (Mimoriet al., 1984; Drawbaugh & Marrs, 1987); the brain is not considered to be a major site of cyanide detoxication. The brain, however, is the target for cyanide toxicity. In this study our goal was also to differentiate the distribution of rhodanese in an area of the brain. We found that the enzyme level is highest in fibrous astrocytes of the white matter. Cyanide-induced brain lesions may thus occur in areas of the brain lacking sufficient sites for detoxication.     

Some properties of the rhodanese system of Thiobacillus denitrificans

1. Rhodanese has been extracted from Thiobacillus denitrificans by ultrasonic disintegration of the cells. 2. Studies with Sephadex columns have shown that the enzyme aggregates, forming a tetramer. 3. The molecular weights of the monomer and of an enzymically active sub-unit one-quarter this size have been determined by gel filtration. 4. Higher-molecular-weight forms of rhodanese are broken down by mercaptoethanol to enzymically active fragments of mol.wt. 7000 and 2000 respectively. 5. It is suggested that these fragments are linked in vivo via disulphide bridges to form the monomer, which can then aggregate via further disulphide links. 6. The fragment of mol.wt. 7000 has been obtained in a substantially pure state. 7. Both disulphide and thiol groups are necessary for enzyme activity. 8. Similarities and differences existing between bacterial rhodanese, mammalian rhodanese and beta-mercaptopyruvate sulphurtransferase are discussed.     

Ferrous iron-dependent volatilization of mercury by the plasma membrane of Thiobacillus ferrooxidans

Of 100 strains of iron-oxidizing bacteria isolated, Thiobacillus ferrooxidans SUG 2-2 was the most resistant to mercury toxicity and could grow in an Fe(2+) medium (pH 2.5) supplemented with 6 microM Hg(2+). In contrast, T. ferrooxidans AP19-3, a mercury-sensitive T. ferrooxidans strain, could not grow with 0.7 microM Hg(2+). When incubated for 3 h in a salt solution (pH 2.5) with 0.7 microM Hg(2+), resting cells of resistant and sensitive strains volatilized approximately 20 and 1.7%, respectively, of the total mercury added. The amount of mercury volatilized by resistant cells, but not by sensitive cells, increased to 62% when Fe(2+) was added. The optimum pH and temperature for mercury volatilization activity were 2.3 and 30 degrees C, respectively. Sodium cyanide, sodium molybdate, sodium tungstate, and silver nitrate strongly inhibited the Fe(2+)-dependent mercury volatilization activity of T. ferrooxidans. When incubated in a salt solution (pH 3.8) with 0.7 microM Hg(2+) and 1 mM Fe(2+), plasma membranes prepared from resistant cells volatilized 48% of the total mercury added after 5 days of incubation. However, the membrane did not have mercury reductase activity with NADPH as an electron donor. Fe(2+)-dependent mercury volatilization activity was not observed with plasma membranes pretreated with 2 mM sodium cyanide. Rusticyanin from resistant cells activated iron oxidation activity of the plasma membrane and activated the Fe(2+)-dependent mercury volatilization activity of the plasma membrane.     

Mercaptopyruvate sulfurtransferase as a defense against cyanide toxication: molecular properties and mode of detoxification.

In cyanide poisoning, metalloproteins and carbonyl groups containing proteins are the main target molecules of nucleophilic attack by cyanide. To defend against this attack, cyanide is metabolized to less toxic thiocyanate via transsulfuration. This reaction is catalyzed by rhodanese and mercaptopyruvate sulfurtransferase (MST). Rhodanese is a well characterized mitochondrial enzyme. On the other hand, little was known about MST because it was unstable and difficult to purify. We first purified MST to homogeneity and cloned MST cDNA from rat liver to characterize MST. We also found that MST was an evolutionarily related enzyme of rhodanese. MST and rhodanese are widely distributed in rat tissues, and the kidney and liver prominently contain these enzymes. Immunohistochemical study revealed that MST is mainly distributed in proximal tubular epithelial cells in the kidney, pericentral hepatocytes in the liver, the perinuclear area of myocardial cells in the heart, and glial cells in the brain, and immunoelectron microscopical study concluded that MST was distributed in both cytoplasm and mitochondria, so that MST first detoxifies cyanide in cytoplasm and the cyanide which escapes from catalysis due to MST enters mitochondria. MST then detoxifies cyanide again in cooperation with rhodanese in mitochondria. Tissues other than the liver and kidney are more susceptible to cyanide toxicity because they contain less MST and rhodanese. Even in the same tissue, sensitivity to cyanide toxicity may differ according to the kind of cell. It is determined by a balance between the amount of proteins to be attacked and that of enzymes to defend.     

Characterization of Rhodanese from Cassava Leaves and Tubers

Rhodanese activity has been established in the leaves, in thepeel, and in the flesh of the tuberous part of Manihot esculentaCrantz. The pattern of distribution of enzyme activity is shownto follow that of the concentration of the cyanogenic glucosideestimated on the basis of HCN released. For the first time,the presence of rhodanese is reported in higher plant tissuesother than the leaves. Identity has been established betweenrhodanese from peel, leaves, and flesh of the cassava plant.The enzyme is inhibited by cyanide in the absence of thiosuiphateor cysteine. Rhodanese is suggested to play a role in the detoxificationof cyanide in cassava.     

Enzymic comparisons of the inorganic sulfur metabolism in autotrophic and heterotrophic Thiobacillus ferrooxidans.

Activities of enzymes which mediate the oxidation of thiosulfate to sulfate and the assimilation of sulfate to sulfide were assayed in various cell-free fractions of Thiobacillus ferrooxidans grown autotrophically on either ferrous iron or thiosulfate or heterotrophically on glucose. There was no activity of the thiosulfate-oxidizing enzyme in extracts of bacteria grown with ferrous iron. Comparable activities for ATP-sulfurylase (EC 2.7.7.4), ADP-sulfurylase (EC 2.7.7.5), and adenylate kinase (EC 2.7.4.3) were found in the bacteria grown autotrophically with either Fe2+ or S2O32- or heterotrophically with glucose.     

Mechanism of microbial flotation using Thiobacillus ferrooxidans for pyrite suppression

Microbial desulfurization might be developed as a new process for the removal of pyrite sulfur from coal sluries such as coal-water mixture (CWM). An application of iron-oxidizing bacterium Thiobacillus ferrooxidans to flotation would shorten the periods of the microbial removal of pyrite from some weeks by leaching methods to a few minutes. The floatability of pyrite in flotation was mainly reduced by T. ferrooxidans itself rather than by other microbial substances in bacterial culture as additive of flotation liquor. Floatability was suppressed within a few seconds by bacterial contact. The suppression was proportional to increasing the number of cells observed between bacterial adhesion and the suppression of floatability. If 25% of the total pyrite surface area covered with the bacteria, pyrite floatability would be completely depressed. Bacteria that lost their iron-oxidizing activities by sodium cyanide treatment were also able to adhere to pyrite and reduced pyrite floatability as much as normal bacteria did. Thiobacillus ferrooxidans ATCC 23270, T-1, 9, and 11, which had different iron-oxidizing abilities, suppressed floatability to similar-levels. The oxidizing ability of bacteria did not influence the suppressing effect. These results showed the mechanism of the suppression of pyrite floatability by bacteria. Quick bacterial adhesion to pyrite induced floatability suppression by changing the surface property from hydrophobic. The quick adhesion of the bacterium was the novel function which worked to change the surface property of pyrite to remove it from coal. (c) 1993 John Wiley & Sons, Inc.     

Bovine mitochondrial rhodanese is a phosphoprotein

The mitochondrial sulfurtransferase, rhodanese, has been analyzed for phosphate content. Significant amounts of protein-bound phosphate (30-40%) were measured in the six rhodanese preparations examined. Chromatographic experiments followed by phosphate analyses done on two of the preparations indicated that rhodanese A and rhodanese B, two enzyme forms that were previously resolved on DEAE-Sephadex by Blumenthal and Heinrikson (Blumenthal, K., and Heinrikson, R. L. (1971) J. Biol. Chem. 240, 2430-2437), correspond to dephospho- and phosphorhodanese, respectively. The phosphorylation of rhodanese by [gamma-32P]ATP is catalyzed by cAMP-dependent protein kinase. The stoichiometry of 32P incorporation based on the amount of dephosphorhodanese in the enzyme preparation approaches 1.0. The phosphorylation site is accessible in rhodanese that is free of substrate sulfur but not in the covalent enzyme-sulfur intermediate which is formed as an obligatory step during the course of catalysis. Because the cellular localization of cAMP-dependent protein kinase makes it unlikely as the physiologic modulator of rhodanese activity, liver extracts have been tested for a rhodanese kinase that does not require cAMP. Rhodanese kinase activity which is independent of cAMP is observed in extract fractions resolved by Affi-Gel Blue chromatography and freed from endogenous rhodanese by chromatography on Sephadex G-100. These results together with previous findings from this and other laboratories have led to a working model of a bicyclic cascade system that can modulate the rate of mitochondrial respiration. The essence of the model is a transduction and amplification of cellular signals into the altered covalent phosphorylation of rhodanese. Rhodanese, in turn, serves as a converter enzyme which directly alters the rate of the respiratory chain and, thus, ATP production by the reversible sulfuration of key iron-sulfur centers. The model, when expanded to include signal pathways initiated by hormones or neurotransmitters, represents a mechanism by which mitochondria can recognize and meet changing energy demands.     

Degradation of cyanide by Trichoderma mutants constructed by restriction enzyme mediated integration (REMI)

REMI technique was used to construct mutants with improved cyanide-degradation ability from biocontrol fungus Trichoderma koningii strain T30. The plasmid pV2 transformation was confirmed by PCR and Southern blot analysis. Out of 21 transformants, 15 single-copied transformants (71.4%) were found. To compare enzyme activities of rhodanese and cyanide hydratase, T. atroviride T23, T. harzianum T21 and their transformants constructed by REMI previously were also included. Transformants TkB6 (0.173 micromols thiocyanate formed min(-1)mg protein(-1)) from T30 and TaK1 (0.174 micromols thiocyanate formed min(-1)mg protein(-1)) from T23 showed higher rhodanese activity than other transformants and their wild strains. TkA9 (5.53 micromols formamide formed h(-1)mg protein(-1)) from T30 and Th64 (5.35 micromols formamide formed h(-1)mg protein(-1)) from T21 had higher cyanide hydratase activity than other transformants and their wild strains.     

Identification of putative sulfurtransferase genes in the extremophilic Acidithiobacillus ferrooxidans ATCC 23270 genome: structural and functional characterization of the proteins

Eight nucleotide sequences containing a single rhodanese domain were found in the Acidithiobacillus ferrooxidans ATCC 23270 genome: p11, p14, p14.3, p15, p16, p16.2, p21, and p28. Amino acids sequence comparisons allowed us to identify the potentially catalytic Cys residues and other highly conserved rhodanese family features in all eight proteins. The genomic contexts of some of the rhodanese-like genes and the determination of their expression at the mRNA level by using macroarrays suggested their implication in sulfur oxidation and metabolism, formation of Fe-S clusters or detoxification mechanisms. Several of the putative rhodanese genes were successfully isolated, cloned and overexpressed in E. coli and their thiosulfate:cyanide sulfurtransferase (TST) and 3-mercaptopyruvate/cyanide sulfurtransferase (MST) activities were determined. Based on their sulfurtransferase activities and on structural comparisons of catalytic sites and electrostatic potentials between homology- modeled A. ferrooxidans rhodaneses and the reported crystal structures of E. coli GlpE (TST) and SseA (MST) proteins, two of the rhodanese-like proteins (P15 and P16.2) could clearly be defined as TSTs, and P14 and P16 could possibly correspond to MSTs. Nevertheless, several of the eight A. ferrooxidans rhodanese-like proteins may have some different functional activities yet to be discovered.     

Comparative studies on the distribution of rhodanese in different tissues of domestic animals.

1. The activity of rhodanese in different tissues of some domestic animals was measured. 2. Rhodanese was present in all tissues studied. 3. The activity of rhodanese in most tissues of sheep was higher than other animals studied. 4. In sheep and cattle the epithelium of rumen, omasum and reticulum were the richest sources of rhodanese. Significant activity of rhodanese was also present in liver and kidney. 5. In camel the liver contained the highest level of rhodanese followed by lung and rumen epithelium. Camel liver contained a third of the activity of sheep liver. 6. Equine liver had a third of the activity of sheep liver. Other tissues showed low levels of rhodanese activity. 7. Dog liver contained only 4% of the activity of sheep liver. In this animal, brain was the richest source of rhodanese. 8. The results are discussed in terms of efficacy of different tissues of animals in cyanide detoxification.     

Distribution of rhodanese in different parts of the urogenital systems of sheep at pre- and post-natal stages

The enzyme rhodanese (thiosulfate:cyanide sulfurtransferase) is a ubiquitous enzyme present in all living organisms, from bacteria to humans and plays a central role in cyanide detoxification. The purpose of this investigation is to determine and compare rhodanese activity in different parts of urogenital systems of male and female sheep fetuses at 2.5, 3, 3.5, 4, 4.5, and 5 months of age. The highest activity of rhodanese in male fetus was in kidney cortex, followed by medulla of the kidney. No significant difference was observed in other organs. In female fetus, the highest activity was in kidney cortex followed by oviduct and medulla of kidney. The enzyme activity of tissues increased with age. There was no significant difference (P > 0.05) between male and female fetuses in levels of rhodanese activity of different tissues except in urinary bladder at 2.5 and 3 months and in urethra at 4.5 months of age. The results of this study might indicate the involvement of rhodanese in cyanide detoxification in tissues which are more exposed to cyanide. On the other hand, rhodanese might perform other functions which are specific in these tissues.