Activity Of 3-mercaptopyruvate Sulfurtransferase Research Articles

Hypoxia-Induced Changes in L-Cysteine Metabolism and Antioxidative Processes in Melanoma Cells.

This study was performed on human primary (WM115) and metastatic (WM266-4) melanoma cell lines developed from the same individual. The expression of proteins involved in L-cysteine metabolism (sulfurtransferases, and cystathionine β-synthase) and antioxidative processes (thioredoxin, thioredoxin reductase-1, glutathione peroxidase, superoxide dismutase 1) as well as the level of sufane sulfur, and cell proliferation under hypoxic conditions were investigated. Hypoxia in WM115 and WM266-4 cells was confirmed by induced expression of carbonic anhydrase IX and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 4 by the RT-PCR and Western blot methods. It was shown that, under hypoxic conditions the inhibition of WM115 and WM266-4 melanoma cell proliferation was associated with decreased expression of thioredoxin reductase-1 and cystathionine β-synthase. These two enzymes may be important therapeutic targets in the treatment of melanoma. Interestingly, it was also found that in normoxia the expression and activity of 3-mercaptopyruvate sulfurtransferase in metastatic WM266-4 melanoma cells was significantly higher than in primary melanoma WM115 cells.

Sulfanegen stimulates 3-mercaptopyruvate sulfurtransferase activity and ameliorates Alzheimer's disease pathology and oxidative stress in vivo

Increased oxidative stress and inflammation are implicated in the pathogenesis of Alzheimer's disease. Treatment with hydrogen sulfide (H2S) and H2S donors such as sodium hydrosulfide (NaSH) can reduce oxidative stress in preclinical studies, however clinical benefits of such treatments are rather ambiguous. This is partly due to poor stability and bioavailability of the H2S donors, requiring impractically large doses that are associated with dose-limiting toxicity. Herein, we identified a bioavailable 3-mercaptopyruvate prodrug, sulfanegen, which is able to pose as a sacrificial redox substrate for 3-mercaptopyruvate sulfurtransferase (3MST), one of the H2S biosynthetic enzymes in the brain. Sulfanegen is able to mitigate toxicity emanating from oxidative insults and the Aβ1-42 peptide by releasing H2S through the 3MST pathway. When administered to symptomatic transgenic mouse model of AD (APP/PS1; 7 and 12 months) and mice that were intracerebroventricularly administered with the Aβ1-42 peptide, sulfanegen was able to reverse oxidative and neuroinflammatory consequences of AD pathology by restoring 3MST function. Quantitative neuropathological analyses confirmed significant disease modifying effect of the compound on amyloid plaque burden and brain inflammatory markers. More importantly, sulfanegen treatment attenuated progressive neurodegeneration in these mice, as evident from the restoration of TH+ neurons in the locus coeruleus. This study demonstrates a previously unknown concept that supplementation of 3MST function in the brain may be a viable approach for the management of AD. Finally, brought into the spotlight is the potential of sulfanegen as a promising AD therapeutic for future drug development efforts.

Heparan Sulfate, Mucopolysaccharidosis IIIB and Sulfur Metabolism Disorders.

Mucopolysaccharidosis, type IIIB (MPS IIIB) is a rare disease caused by mutations in the N-alpha-acetylglucosaminidase (NAGLU) gene resulting in decreased or absent enzyme activity. On the cellular level, the disorder is characterized by the massive lysosomal storage of heparan sulfate (HS)—one species of glycosaminoglycans. HS is a sulfur-rich macromolecule, and its accumulation should affect the turnover of total sulfur in cells; according to the studies presented here, it, indeed, does. The lysosomal degradation of HS in cells produces monosaccharides and inorganic sulfate (SO42−). Sulfate is a product of L-cysteine metabolism, and any disruption of its levels affects the entire L-cysteine catabolism pathway, which was first reported in 2019. It is known that L-cysteine level is elevated in cells with the Naglu−/− gene mutation and in selected tissues of individuals with MPS IIIB. The level of glutathione and the Naglu−/− cells’ antioxidant potential are significantly reduced, as well as the activity of 3-mercaptopyruvate sulfurtransferase (MPST, EC 2.8.1.2) and the level of sulfane sulfur-containing compounds. The direct reason is not yet known. This paper attempts to identify some of cause-and-effect correlations that may lead to this condition and identifies research directions that should be explored.

Activation of 3-Mercaptopyruvate Sulfurtransferase by Glutaredoxin Reducing System.

Glutaredoxin (EC 1.15–1.21) is known as an oxidoreductase that protects cysteine residues within proteins against oxidative stress. Glutaredoxin catalyzes an electron transfer reaction that donates an electron to substrate proteins in the reducing system composed of glutaredoxin, glutathione, glutathione reductase, and nicotinamide-adenine dinucleotide phosphate (reduced form). 3-mercaptopyruvate sulfurtransferase (EC 2.8.1.2) is a cysteine enzyme that catalyzes transsulfuration, and glutaredoxin activates 3-mercaptopyruvate sulfurtransferase in the reducing system. Interestingly, even when glutathione or glutathione reductase was absent, 3-mercaptopyruvate sulfurtransferase activity increased, probably because reduced glutaredoxin was partly present and able to activate 3-mercaptopyruvate sulfurtransferase until depletion. A study using mutant Escherichia coli glutaredoxin1 (Cys14 is the binding site of glutathione and was replaced with a Ser residue) confirmed these results. Some inconsistency was noted, and glutaredoxin with higher redox potential than either 3-mercaptopyruvate sulfurtransferase or glutathione reduced 3-mercaptopyruvate sulfurtransferase. However, electron-transfer enzymatically proceeded from glutaredoxin to 3-mercaptopyruvate sulfurtransferase.

3-Mercaptopyruvate sulfurtransferase disruption in dermal fibroblasts facilitates adipogenic trans-differentiation

Transitioning from a differentiated state to a higher-order of plasticity, by partial rather than full reactivation of pluripotency genes, might be a better approach in regenerative medicine. Hydrogen sulfide plays a crucial role in the maintenance and differentiation of mesenchymal stem cells (MSC) that have the potential to differentiate to a diverse group of mesenchymally derived cells. It was shown that these cells show a heavy reliance on cystathionine-β-synthase (CBS)-derived hydrogen sulfide (H2S) during differentiation. We have found that expression and activity of 3-mercaptopyruvate sulfurtransferase (MPST), one of three enzymes that hat regulates H2S biosynthesis, is significantly lower in MSC as compared with lineage-restricted dermal fibroblasts. Here, we tested the hypothesis that suppression of MPST in dermal fibroblasts might induce plasticity-related changes and broaden the transdifferentiation potency. Inactivation of MPST with phenylpyruvate (PP) or by siRNA silencing led to diminished H2S production associated with increased production of reactive oxygen species (ROS) and lactic acid. Accumulation of α-ketoglutarate (α-KG), a key metabolite required for the expression of ten-eleven translocation hydroxylase (TET), was associated with stimulated transcription of pluripotency related genes including OCT4, KLF4, SOX2, and NANOG. Suppression of TET1 gene and inhibition of glycolysis with glucose analog, 2-desoxy-d-glucose, or hexokinase II inhibitor significantly reduced expression of pluripotency genes following MPST inactivation or knockdown. MPST disruption promoted the conversion of fibroblasts into adipocytes as evidenced by a significant increase in expression of adipocyte-specific genes, PPARγ, and UCP1, and intracellular accumulation of oil Red-O positive fat droplets. Inhibition of glycolysis inhibited these changes. Under induced differentiation conditions, fibroblasts with disrupted MPST show the potency to differentiate to white adipogenic lineage. Thus, MPST inactivation or silencing enhances the plasticity of dermal fibroblasts in a TET1 and glycolysis dependent manner and promotes adipogenic transdifferentiation.

Inhibition of Human Neuroblastoma Cell Proliferation by N-acetyl-L-cysteine as a Result of Increased Sulfane Sulfur Level.

In various cancer cells, the level of sulfane sulfur-containing compounds is decreased compared to normal cells. In the present study the effect of N-acetyl-L-cysteine (NAC), which acts as a precursor of H2S synthesis, on the human neuroblastoma SH-SY5Y cell proliferation, the activity of 3-mercaptopyruvate sulfurtransferase (MPST), and the level of sulfane sulfur were investigated. SH-SY5Y cells were treated with NAC, while untreated cells were used as the control. The toxicity of NAC on the cells was studied by the LDH cytotoxicity assay; cell proliferation was examined by the MTT method. MPST activity and sulfane sulfur level were also analyzed in the NAC-treated cells. The addition of NAC to the medium, in non-cytotoxic concentrations, resulted in inhibition of the SH-SY5Y cell proliferation after 48 h of culture. The MPST activity and the level of sulfane sulfur-containing compounds were also elevated under the same culture conditions. The antiproliferative activity of NAC in the SH-SY5Y cells was associated with an increase in the MPST activity and consequently with an increase in the intracellular level of sulfane sulfur in these cells.

Mercaptopyruvate acts as endogenous vasodilator independently of 3-mercaptopyruvate sulfurtransferase activity

Hydrogen sulfide (H2S) is produced by the action of cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) or 3-mercaptopyruvate sulfurtransferase (3-MST). 3-MST converts 3-mercaptopyruvate (MPT) to H2S and pyruvate. H2S is recognized as an endogenous gaseous mediator with multiple regulatory roles in mammalian cells and organisms. In the present study we demonstrate that MPT, the endogenous substrate of 3-MST, acts also as endogenous H2S donor. Colorimetric, amperometric and fluorescence based assays demonstrated that MPT releases H2S in vitro in an enzyme-independent manner. A functional study was performed on aortic rings harvested from C57BL/6 (WT) or 3-MST-knockout (3-MST−/−) mice with and without endothelium. MPT relaxed mouse aortic rings in endothelium-independent manner and at the same extent in both WT and 3-MST−/− mice. N5-(1-Iminoethyl)-l-ornithine dihydrochloride (L-NIO, an inhibitor of endothelial nitric oxide synthase) as well as 1H-[1,2,4]oxadiazolo [4,3-a]quinoxalin-1-one (ODQ, a soluble guanylyl cyclase inhibitor) did not affect MPT relaxant action. Conversely, hemoglobin (as H2S scavenger), as well as glybenclamide (an ATP-dependent potassium channel blocker) markedly reduced MPT-induced relaxation. The functional data clearly confirmed a non enzymatic vascular effect of MPT. In conclusion, MPT acts also as an endogenous H2S donor and not only as 3-MST substrate. MPT could, thus, be further investigated as a means to increase H2S in conditions where H2S bioavailability is reduced such as hypertension, coronary artery disease, diabetes or urogenital tract disease.

A possible mechanism of inhibition of U87MG and SH-SY5Y cancer cell proliferation by diallyl trisulfide and other aspects of its activity

The study was conducted to elucidate the mechanism of antiproliferative and antioxidative action of diallyl trisulfide (DATS), a garlic-derived organosulfur compound. Changes in the l-cysteine desulfuration, and the levels of cystathionine and non-protein thiols in DATS-treated human glioblastoma (U87MG) and neuroblastoma (SH-SY5Y) cells were investigated. The inhibition of proliferation of the investigated cells by DATS was correlated with an increase in the inactivated form of Bcl-2. In U87MG cells, an increased level of sulfane sulfur and an increased activity of 3-mercaptopyruvate sulfurtransferase (MPST) and rhodanese, the enzymes involved in sulfane sulfur generation and transfer, suggest that DATS can function as a donor of sulfane sulfur atom, transferred by sulfurtransferases, to sulfhydryl groups of cysteine residues of Bcl-2 and in this way lower the level of active form of Bcl-2 by S-sulfuration. Diallyl trisulfide antioxidative effects result from an increased level of cystathionine, a precursor of cysteine, and an increased glutathione level. MPST and rhodanese, the level of which is increased in the presence of DATS, can serve as antioxidant proteins.

Is development of high-grade gliomas sulfur-dependent?

We characterized γ-cystathionase, rhodanese and 3-mercaptopyruvate sulfurtransferase activities in various regions of human brain (the cortex, thalamus, hypothalamus, hippocampus, cerebellum and subcortical nuclei) and human gliomas with II to IV grade of malignancy (according to the WHO classification). The human brain regions, as compared to human liver, showed low γ-cystathionase activity. The activity of rhodanese was also much lower and it did not vary significantly between the investigated brain regions. The activity of 3-mercaptopyruvate sulfurtransferase was the highest in the thalamus, hypothalamus and subcortical nuclei and essentially the same level of sulfane sulfur was found in all the investigated brain regions. The investigations demonstrated that the level of sulfane sulfur in gliomas with the highest grades was high in comparison to various human brain regions, and was correlated with a decreased activity of γ-cystathionase, 3-mercaptopyruvate sulfurtransferase and rhodanese. This can suggest sulfane sulfur accumulation and points to its importance for malignant cell proliferation and tumor growth. In gliomas with the highest grades of malignancy, despite decreased levels of total free cysteine and total free glutathione, a high ratio of GSH/GSSG was maintained, which is important for the process of malignant cells proliferation. A high level of sulfane sulfur and high GSH/GSSG ratio could result in the elevated hydrogen sulfide levels. Because of the disappearance of γ-cystathionase activity in high-grade gliomas, it seems to be possible that 3-mercaptopyruvate sulfurtransferase could participate in hydrogen sulfide production. The results confirm sulfur dependence of malignant brain tumors.

Hydrogen Sulfide Is a Signaling Molecule and a Cytoprotectant

Accumulating evidence shows that hydrogen sulfide may function as a signaling molecule in processes such as neuromodulation in the brain and smooth muscle relaxation in the vascular system. It also has a cytoprotective effect, since it can protect neurons and cardiac muscle from oxidative stress and ischemia-reperfusion injury, respectively. Hydrogen sulfide can also modulate inflammation, insulin release, and angiogenesis. The regulation of the activity of 3-mercaptopyruvate sulfur transferase (3MST) along with cysteine aminotransferase (CAT), one of the H(2)S producing pathways, has been demonstrated. The production of H(2)S by the pathway, which is regulated by Ca(2+) and facilitated by thioredoxin and dihydrolipoic acid, is also involved in H(2)S signaling as well as cytoprotection. Sulfur hydration of proteins by H(2)S has been proposed to modulate protein functions. H(2)S-sensitive fluorescent probes, which enable us to measure the localization of H(2)S in real time, have been developed. The basal concentrations of H(2)S have recently been measured and found to be much lower than those initially reported. However, the concentration of H(2)S reached in stimulated cells, as well as the regulation of H(2)S producing enzymes is not well understood. It has been proposed that some of the effects of H(2)S on the regulation of enzymes and receptors might be explained through the properties of sulfane sulfur (S(0)), another form of active sulfur. The determination of H(2)S concentrations in activated cells using new methods including H(2)S-sensitive fluorescent probes, as well as the investigation of the effects of H(2)S using specific inhibitors, may provide better understanding of the physiological function of this molecule. Clarifying mechanisms of H(2)S activity may also facilitate the development of new therapeutic compounds.

Potential therapeutic advantage of ribose-cysteine in the inhibition of astrocytoma cell proliferation

It has been observed that astrocyte and astrocytoma cells differ in their response to D-ribose-L-cysteine (RibCys) in the culture medium. RibCys, a prodrug of L-cysteine, elevates the level of cysteine and glutathione in both astrocytoma and astrocyte cultures. It also affects the activity of two sulfurtransferases, 3-mercaptopyruvate sulfurtransferase and rhodanese, involved in the metabolism of sulfane sulfur-containing compounds and in consequence exerts an effect on the level of sulfane sulfur. Under conditions, in which the raised level of sulfane sulfur was accompanied by an elevated activity of 3-mercaptopyruvate sulfurtransferase, the proliferation of the human astrocytome U373 line was decreased. The experiments were simultaneously performed with murine astrocytes to compare the behavior of normal cells under similar conditions. In murine astrocytes, RibCys was capable of increasing cellular proliferation, and was accompanied by a diminished level of sulfane sulfur and unchanged activity of the two sulfurtransferases. Thus, RibCys might offer a therapeutic advantage in the inhibition of astrocytoma cell proliferation. Besides, in the absence of oxidative stress, measured as the ratio of GSH/GSSG, the obtained results confirm that the fall in the level of sulfane sulfur is associated with increasing proliferation of cells, whereas a rise in the level causes a decrease in the proliferation of U373 cells.

A Novel Mercaptopyruvate Sulfurtransferase Thioredoxin-Dependent Redox-Sensing Molecular Switch: A Mechanism for the Maintenance of Cellular Redox Equilibrium

An intermolecular disulfide bond serves as a thioredoxin-dependent redox-sensing switch for the regulation of the enzymatic activity of 3-mercaptopyruvate sulfurtransferase (MST, EC.2.8.1.2). A cysteine residue on the surface of each subunit was oxidized to form an intersubunit disulfide bond so as to decrease MST activity, and thioredoxin-specific conversion of a dimer to a monomer increased MST activity. Further, a low redox potential sulfenate was reversibly formed at a catalytic site cysteine so as to inhibit MST, and thioredoxin-dependent reduction of the sulfenate restored the MST activity. Concludingly, MST partly contributes to the maintenance of cellular redox homeostasis via exerting control over cysteine catabolism.

Cadmium toxicity related to cysteine metabolism and glutathione levels in frog Rana ridibunda tissues

The level of glutathione and sulfane sulfur and sulfurtransferases activity in adult frogs Rana ridibunda were investigated after the exposure to 40 mg or 80 mg CdCl 2 L − 1 for 96 h or 240 h. Cd accumulation in the liver, kidneys and testes was confirmed, and the highest Cd level was found in the testes. In the liver, the exposure to Cd resulted in an increase of GSH level and the activity of rhodanese, while the activity of 3-mercaptopyruvate sulfurtransferase and cystathionase decreased. The kidneys and brain showed the elevated level of GSH and the activity of all investigated sulfurtransferases, as well as sulfane sulfur especially in brain. In such tissues as the testes, muscles and heart, the level of GSH and the activity of 3-mercaptopyruvate sulfurtransferase were significantly diminished. The increased level of sulfane sulfur was determined in the testes and muscles and the increased activity of rhodanese in the testes and the heart. These findings suggest the possible role of sulfane sulfur and/or sulfurtransferases in the antioxidation processes, which can be generated in cells by cadmium.

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.

Characterization of two sulfurtransferase isozymes from Arabidopsis thaliana.

Sulfurtransferases transfer a sulfane atom from a donor substrate to a thiophilic acceptor molecule. Recently a sulfurtransferase specific for the substrate 3-mercaptopyruvate was isolated from Arabidopsis thaliana [Papenbrock, J. & Schmidt, A. (2000) Eur. J. Biochem. 267, 145-154]. In this study a second sulfurtransferase from Arabidopsis was characterized and compared to the enzyme described previously. Sequences of the mature proteins had an identity of 77.7%. The plant sulfurtransferases formed a distinct group within the known eukaryotic sulfurtransferases. When Southern blots were hybridized with labelled cDNA fragments from each of the plant sulfurtransferases the same pattern of bands was obtained indicating the existence of only these two closely related sulfurtransferases. The new sulfurtransferase was expressed in Escherichia coli fused with an N-terminal His6-tag, purified and tested for enzyme activity. Like the first enzyme, the newly isolated protein preferred 3-mercaptopyruvate to thiosulfate as substrate. The Km of both enzymes determined for 3-mercaptopyruvate and cyanide were almost identical. As a result of database searches it became obvious that sulfurtransferase proteins from higher plants showed high similarities to small senescence- and stress-induced proteins. To prove the involvement of sulfurtransferases in senescence-associated processes 3-mercaptopyruvate sulfurtransferase activity was determined in crude protein extracts from Arabidopsis plants of different ages. 3-mercaptopyruvate sulfurtransferase activity and steady-state RNA levels of sulfurtransferases increased with increasing age. However, steady-state protein levels as measured by using an antibody against the sulfurtransferase protein expressed previously decreased. Putative roles of sulfurtransferases in senescence-associated processes are discussed.

The activity of 3-mercaptopyruvate sulfurtransferase in erythrocytes from patients with polycythemia vera.

The activity of 3-mercaptopyruvate sulfurtransferase in erythrocytes from patients with polycythemia vera.

Effects of thiazolidine-4(R)-carboxylates and other low-molecular-weight sulfur compounds on the activity of mercaptopyruvate sulfurtransferase, rhodanese and cystathionase in Ehrlich ascites tumor cells and tumor-bearing mouse liver

Changes of the specific activity of 3-mercaptopyruvate sulfurtransferase (MPST), rhodanese and cystathionase in Ehrlich ascites tumor cells (EATC) and tumor-bearing mouse liver after intraperitoneal administration of thiazolidine derivatives, L-cysteine, D,L-methionine, thiocystine or thiosulfate were estimated. Thiazolidine derivatives used were: thiazolidine-4-carboxylic acid (CF), 2-methyl-thiazolidine-2,4-dicarboxylic acid (CP) and 2-methyl-thiazolidine-4-carboxylic acid (CA). In the liver, the activity of MPST was significantly increased by all the studied compounds, whereas the activity of rhodanese was by CF and thiocystine and that of cystathionase was by the administration of cysteine and CP. Un the other hand, cysteine lowered the rhodanese activity and the activity of cystathionase was decreased by the administration of methionine and thiocystine. Activities of MPST and rhodanese were even lower in EATC than those in the liver of tumor-bearing mouse and the activity of cystathionase in EATC was not be detected. The thiazolidine derivatives significantly increased the level of MPST activity in EATC, but decreased the rhodanese activity. Thiosulfate also increased the activity of MPST to a lesser degree, but cysteine, methionine and thiocystine gave little change in the activity. The rhodanese activity in EATC was slightly increased only by thiocystine. These findings suggest that the sulfur metabolism in the tumor-bearing mouse liver is different from that in the normal mouse liver, and that sulfur compounds are minimally metabolized to sulfane sulfur, a labile sulfur, in EATC.

14-141 - 3-mercaptopyruvate sulfurtransferase activity in brain and liver in the mouse

14-141 - 3-mercaptopyruvate sulfurtransferase activity in brain and liver in the mouse

Tissue-Specific Bioenergetic Effects and Increased Enzymatic Activities Following Acute Sublethal Peroral Exposure to Cyanide in the Mallard Duck

Protection of wildlife and in particular migratory birds, which are protected by the Migratory Bird Treaty Act, from cyanide waste in and around gold mining operations is an important environmental issue. We have investigated the bioenergetic effects of sublethal peroral cyanide exposure using the mallard duck (Anus platyrhynchos) as a model migratory bird. At cyanide concentrations well below levels considered safe by the mining industry and some regulatory agencies (50 ppm weak acid dissociable (WAD) cyanide) significant depletions of heart, liver, and brain tissue ATP levels were observed. Tissue ATP levels were restored to normal by 24 hr postexposure. Rhodanese and 3-mercaptopyruvate sulfurtransferase activities were determined in these tissues both for basal activity and post-cyanide exposure. Only brain tissue showed increased enzymatic activity following cyanide exposure, suggesting tissue-specific regulation of these enzymatic activities. These studies suggest that 50 ppm WAD cyanide is not a safe level of cyanide in water where avian wildlife exposure can occur.

L-Cysteine Metabolism in Guinea Pig and Rat Tissues

Rhodanese, γ-cystathionase and 3-mercaptopyruvate sulfurtransferase activities were examined in guinea pig and rat liver, kidney and brain. In the liver of both species rhodanese showed the same high range of activity but in guinea pig kidney and brain a slightly lower level was determined than that in corresponding rat tissues. The 3-mercaptopyruvate sulfurtransferase and γ-cystathionase activities in all the investigated tissues of guinea pig were significantly lower than those in rat. The sulfane sulfur pool, a source of sulfur transferred by rhodanese, can be augmented in vitro in guinea pig liver, but not in rat liver when 3-mercaptolactate-cysteine disulfide is used as a substrate of γ-cystathionase.