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PubMed1964

INDUCTION AND MECHANISMS OF ARSENITE RESISTANCE IN PSEUDOMONAS PSEUDOMALLEI.

Arima, Kei (University of Tokyo, Tokyo, Japan), and Michiko Beppu. Induction and mechanisms of arsenite resistance in Pseudomonas pseudomallei. J. Bacteriol. 88:143-150. 1964.-Pseudomonas pseudomallei strain 54, able to grow in the presence of 2 x 10(-2)m arsenite, was isolated from soil. After a short lag period, it grew at a normal growth rate. In the organisms grown with 10(-2)m arsenite, oxidation of alpha-ketoglutarate and other substrates proceeded in the presence of the same concentration of the drug. The concentration of arsenite which was half-inhibitory to alpha-ketoglutarate oxidation was 1.6 x 10(-3)m in the sensitive bacteria and 3.3 x 10(-2)m in the resistant ones. Cells capable of oxidizing alpha-ketoglutarate in the presence of arsenite were induced rapidly by contact with arsenite in growing cultures; when the drug was removed from the cultures, resistance was maintained for about two generations and then gradually disappeared. From the data presented, it was concluded that resistance in this organism is a physiological change and not a hereditary one. Further studies were carried out to investigate the arsenite-resistance mechanisms. alpha-Ketoglutarate dehydrogenase activity in the cell-free extracts of the resistant bacteria was sensitive to arsenite. An increase in the contents of this enzyme and sulfhydryl compounds, involving lipoic acid, was not observed in the resistant bacteria. The possibility of detoxication of arsenite was ruled out. Treatment of the resistant cells with cetyl-trimethylammonium bromide made them susceptible to 2 x 10(-2)m arsenite, although untreated cells were resistant to the same concentration of the drug. These data suggest the decreased permeability to arsenite of the resistant bacteria as a main mechanism of resistance.

Ammonium Compounds↗
PubMed1982

S-Adenosylhomocysteinase from mouse liver. Inactivation of the enzyme in the presence of metabolites.

1. S-Adenosylhomocysteinase (S-adenosylhomocysteine hydrolase, EC 3.3.1.1) was slowly inactivated in the presence of adenine and adenine nucleotides (Ueland & Saebø, 1979b). 2. The enzyme was stabilized by 2-mercaptoethanol and dithiothreitol, and was slowly inactivated at 37 degrees C in the absence of reducing agents and rapidly inactivated in the presence of 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB). The inactivation (both in the absence and presence of DTNB) was partly prevented by adenine, AMP and ADP. 3. A slow decrease in enzyme activity was observed in the presence of AMP, ADP and ATP, and this process was enhanced by sulfhydryl compounds like L-homocysteine, L-cysteine, 2-mercapthoethanol and dithiothreitol. 4. Inactivation of the enzyme by adenine was independent of sulfhydryl compounds, and was characterized by an initial phase showing first-order kinetics and saturability with respect to adenine. 5. Inorganic phosphate nearly abolished the inactivation of S-adenosylhomocysteinase induced by both adenine nucleotides and adenine. 6. The enzyme activity was recovered when adenine was removed by dilution or gel filtration. Attempts to reverse the effect of adenine nucleotides on the enzyme were not successful. 7. The effect of adenine nucleotides was a Vmax-effect, and the inactivation was not associated with dissociation or polymerization of the enzyme or dissociation of enzyme-bound NAD.

Adenine↗
PubMed1973

Bactericidal action of sulfhydryl binding compounds.

An oxidation product of indole-3-acetic acid, 3-methyleneoxindole, is highly reactive with free sulfhydryl groups. It has been shown to be a potent bactericidal agent in actively growing cultures. The bactericidal action of 3-methyleneoxindole was found to be independent of protein or deoxyribonucleic acid synthesis but to require the capacity for ribonucleic acid synthesis. The reactions underlying the bactericidal effect of 3-methyleneoxindole are not unique to it among compounds which can bind free SH groups, since N-ethylmaleimide appeared to have a similar mode of action.

Chloramphenicol↗
PubMed1983

Respiratory activities of in vitro grown Mycobacterium lepraemurium.

Mycobacterium lepraemurium was cultivated on Ogawa egg-yolk medium and its respiratory activities using several substrates were investigated. Glycerol and succinate were oxidized at a slow rate by the cell-free extracts prepared from in vitro grown Hawaiian and Keishicho strains of M. lepraemurium. None of the other intermediates of the glycolysis cycle as well as of the tricarboxylic acid cycle was oxidized by the whole cell suspensions or cell-free extracts. Likewise, many sulfur compounds such as cystine, mercaptosuccinate, monothioglycerol, thioacetate, etc., were inactive. However, sulfhydryl compounds such as L-cysteine, D-cysteine, DL-cysteine, dithioerythritol, dithiothritol, and DL-penicillamine were actively oxidized. Yeast extract was also readily oxidized by cell suspensions of in vitro grown M. lepraemurium. Tween 80 was very poorly oxidized by whole cell suspensions but the cell-free preparations catalyzed an active oxidation of Tween 80. While bovine serum albumin was oxidized at a slow rate by cell-free extracts, egg albumin was inactive. The thiol-binding agents, p-hydroxymercuribenzoate and N-ethylmaleimide were effective inhibitors of succinate and NADH oxidation, thus indicating the involvement of sulfhydryl compounds in the metabolism of M. lepraemurium.

In Vitro Techniques↗
PubMed1978

Evidence for a role of sulfhydryl groups in catalytic activity and subunit interaction of the cyclic GMP-dependent protein kinase from silkworm.

Guanosine 3':5'-monophosphate-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) has been isolated from silkworm pupal fat body (Bombyx mori) which is devoid of any adenosine 3':5'-monophosphate-dependent protein kinase. The enzyme displayed catalytic properties which were roughly similar to those described for adenosine 3':5'-monophosphate-dependent protein kinase. This similarity has been found in substrate specificity, optimal Mg2+ dependency, polyamines effects and the lack of dependency upon sulfhydryl compound for activation by cyclic GMP. Treatment of the enzyme with sulfhydryl reagents, N-ethylmaleimide or p-chloromercuribenzoic acid, inhibited the catalytic activity as well as the dissociation of the binding and catalytic activities as shown by means of sucrose-density gradient ultracentrifugation. In the presence of cyclic GMP or histone, the disulfide-linked structure did not dissociate into separate subunits nor did it migrate as the holoenzyme but sedimented as an intermediate form carrying both binding and catalytic activities.

Animals↗
PubMed1995

Characteristics of rabbit muscle adenylate kinase inhibition by sulfur and recovery by dithiothreitol.

Structure-function relationships of rabbit muscle adenylate kinase (RMAK) were studied by examining the characteristics of inhibitions by hydrophobic inhibitors and reactivations by sulfhydryl reagents. RMAK is inhibited by 1-butanol,N-ethylmaleimide (NEM) and elemental sulfur (S8) with increasing effectiveness in the order of increasing hydrophobicity. Characteristics of these hydrophobic inhibitors are compared with inhibitors forming covalent bonds or reversible complexes. A mechanism is proposed for hydrophobic inhibitors of RMAK that involves conformational changes promoted by interacting with hydrophobic regions. The reversal of RMAK inhibition by sulfhydryl compounds involves a conformational change that exposes hydrophobic regions and the inhibitor to water. Circular dichroism (CD) data show changes in the secondary structures of RMAK, indicating that the inhibitors and the sulfhydryl compounds promote conformational changes. The results of these studies show that the activity of a small enzyme can be controlled in a manner analogous to the allosteric control of larger enzymes.

Adenosine Triphosphate↗
PubMed1985

Involvement of disulfide-sulfhydryl interaction in anti-platelet actions of KF4939.

We studied on the role of an intramolecular disulfide bond of KF4939 in its anti-platelet actions by using rabbit platelets. The inhibitions of aggregation of platelet-rich plasma (PRP) and washed platelets, and of malondialdehyde production in thrombin-stimulated platelets by KF4939 were counteracted by pretreatment with sulfhydryl compounds, glutathione, 1-cysteine and dithiothreitol. A reduced compound of KF4939 (Red-KF4939) showed nearly equal anti-aggregating activities to those of KF4939 in PRP, it, however, showed low activities to inhibit platelet aggregation and thrombin -stimulated malondialdehyde production in washed platelet suspensions. In addition, the anti-aggregating action of Red-KF4939 was counteracted by pretreatment with sulfhydryl compounds, similarly to that of KF4939. Furthermore, when platelets were treated with KF4939, a significant decrease of protein-bound sulfhydryl groups was observed. We may conclude from these results that the intramolecular disulfide bond plays an essential role in anti-platelet actions of KF4939 and the interaction of the disulfide bond with protein-bound sulfhydryl groups may be involved in the mechanism of anti-platelet actions of KF4939.

Animals↗
PubMed1989

Protection of gastric epithelial cell monolayers from a human cell line by omeprazole in vitro.

Omeprazole has an anti-ulcerogenic effect and protects rat gastric mucosa against drug-induced damage in vivo. We have evaluated omeprazole protection against damage induced by sodium taurocholate to gastric epithelial cell monolayers, an experimental model that completely excludes the influence of systemic factors. Furthermore, since our model consists of mucus-producing cells, the acid inhibitory effect of the drug in any protection is negligible. The role of prostaglandin and sulfhydryls in any such protection has also been evaluated. Monolayers of gastric cells from a well-differentiated human cell line were studied. A chromium-51 release assay was used to assess cell damage. Sodium taurocholate damaged cells dose-dependently (r = 0.97, p less than 0.01). Pretreatment with omeprazole significantly reduced the amount of cell damage brought about by sodium taurocholate (p less than 0.001). Indomethacin did not prevent the protection afforded by omeprazole, nor did incubation with omeprazole increase the amount of prostaglandin E2 produced by cultured cells. Omeprazole did not increase the amount of sulfhydryl compounds in cultured cells. These results indicate that omeprazole protects gastric cells independently of systemic factors and of inhibition of gastric acid secretion. This protection is not related to stimulation of prostaglandin synthesis nor is it associated with an increase of endogenous sulfhydryl compounds.

Cell Line↗
PubMedDate not supplied

The effect of heparegen on antioxidant enzyme activities in ethanol-induced liver injury in rats.

SOD, CAT, GSH-Px, and sulfhydryl compounds MDA contents in liver of rats treated with heparegen for 7, 14, and 21 days after alcoholic liver injury have been investigated. After use of this drug, we found beneficial effects on GSH-Px activity, sulfhydryl compounds (total and nonprotein), and MDA content and a partially beneficial effect on SOD and CAT activities. These enzyme activities after 21 days of drug administration were restored. Furthermore, heparegen shortens the time necessary for the return of AIAT and GGTP to normal value. This enzymatic data are supported by histological studies in light microscopy.

Animals↗
PubMed1976

Studies on the in vivo formation of acrolein: 3-hydroxy-propylmercapturic acid as an index of cyclophosphamide (NSC-26271) activation.

3-Hydroxypropylmercapturic acid (MCA) has been quantitatively determined in the urine of rats given cyclophosphamide (CP), related antineoplastic agents, allyl alcohol, or acrolein, with a simple procedure involving the use of an amino-acid analyzer. Male rats (300-400 g) injected with CP (50mg [179.1 mumols]/kg of body weight) excreted 16.7 mumols of MCA/kg in their 24-hour urine. Equivalent amounts of isophosphamide produced 9.0; triphosphamide, 16.1; ASTA-5607, 7.2; ASTA-5122, 4.1; and cytoxyl alcohol, 0.4mumols of MCA/kg. From allyl alcohol and acrolein, 26.3 and 19.7 mumols of MCA/kg were obtained respectively. MCA values were directly proportional to drug dose levels. Since acrolein and phosphorodiamidic acid mustard are the toxic decomposition products of aldophosphamide, and acrolein conjugation appears to be the first step for MCA formation values for MCA would reflect active CP levels. The in vitro interaction of acrolein with glutathione, other sulfhydryl compounds, and a few amino acids at concentrations of 0.15 mumols/ml was also studied. The decrease of acrolein's main absorption peak at 209 nm was used to follow its reaction rate. The faster interactions observed were with the sulfhydryl compounds, where a 50% decrease of absorption in interactions with glutathione and cysteine (at pH 7.4 and 23 degrees C) took place in 111 and 30 seconds respectively. Incubation of these adducts at 37 degrees C and 100 degrees C generated acrolein with a maximum recovery yield of 83% at 100 degrees C. Five patients given 1 g of CP iv excreted 6.4-50 mumols of MCA in their urine in 6 hours.

Acetylcysteine↗
PubMed2006

Metal ion substitution in the catalytic site greatly affects the binding of sulfhydryl-containing compounds to leucyl aminopeptidase.

Bovine lens leucyl aminopeptidase (blLAP), a homohexameric metallopeptidase preferring bulky and hydrophobic amino acids at the N-terminus of (di)peptides, contains two Zn(2+) ions per subunit that are essential for catalytic activity. They may be replaced by other divalent cations with different exchange kinetics. The protein readily exchangeable site (site 1) can be occupied by Zn(2+), Mn(2+), Mg(2+), or Co(2+), while the tight binding site (site 2) can be occupied by Zn(2+) or Co(2+). We recently reported that introduction of Mn(2+) into site 1 generates a novel activity of blLAP toward CysGly [Cappiello, M., et al. (2004) Biochem. J. 378, 35-44], which in contrast is not hydrolyzed by the (Zn/Zn) enzyme. This finding, while disclosing a potential specific role for blLAP in glutathione metabolism, raised a question about the features required for molecules to be a substrate for the enzyme. To clarify the interaction of the enzyme with sulfhydryl-containing derivatives, (Zn/Zn)- and (Mn/Zn)blLAP forms were prepared and functional-structural studies were undertaken. Thus, a kinetic analysis of various compounds with both enzyme forms was performed; the crystal structure of (Zn/Zn)blLAP in complex with the peptidomimetic derivative Zofenoprilat was determined, and a modeling study on the CysGly-(Zn/Zn)blLAP complex was carried out. This combined approach provided insight into the interaction of blLAP with sulfhydryl-containing derivatives, showing that the metal exchange in site 1 modulates binding to these molecules that may result in enzyme substrates or inhibitors, depending on the nature of the metal.

Binding Sites↗
PubMed1990

Determination and metabolism of dithiol chelating agents: X. In humans, meso-2,3-dimercaptosuccinic acid is bound to plasma proteins via mixed disulfide formation.

meso-2,3-Dimercaptosuccinic acid (DMSA) is orally effective for the treatment of chronic lead intoxication in humans. Earlier studies have shown that the majority of DMSA, given p.o. to normal humans, is excreted in the urine as mixed disulfides with L-cysteine. We have developed an assay for the determination of DMSA that has made possible the determination of the form of DMSA in blood and plasma. After p.o. administration of 10 mg DMSA/kg to four normal young men, no unaltered DMSA (unaltered DMSA is the unbound, parent compound; total DMSA consists of unaltered DMSA plus oxidized (disulfide) DMSA and is determined after reduction with dithiothreitol) was found in the blood over an 8-hr period. Only after treatment of blood or plasma with the disulfide-reducing agent, dithiothreitol, was DMSA detected. This indicates that DMSA is in disulfide linkage with plasma proteins and/or non-protein sulfhydryl compounds. Most of the DMSA in the plasma (92-95%) was found to be bound to plasma proteins, mainly albumin. The remaining DMSA may be bound to small molecular weight (less than 10,000 MW) nonprotein sulfhydryl compounds such as cysteine. Plasma protein appears to serve as a depot and reservoir of DMSA, which can exchange for cysteine. The urinary excretion of unaltered DMSA and DMSA mixed disulfides with L-cysteine suggests that this exchange takes place at the kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMedDate not supplied

Antioxidant status of liver, erythrocytes, and blood serum of rats in acute methanol intoxication.

SOD, CAT, GSH-Px, GSSG-R, ascorbic acid, alpha-tocopherol, nonprotein- and protein-bound sulfhydryl compounds, and TBA-rs content in the liver, erythrocytes, and blood serum of rats treated with methanol after 6, 12, and 24 h and 2, 5, and 7 days were investigated. Furthermore, hematological parameters of erythrocytes were analysed. GSH-Px, GSSG-R, sulfhydryl compounds, and ascorbic acid in the liver, erythrocytes, and in blood serum were significantly decreased. In addition, Cu,Zn-SOD and tocopherol in erythrocytes were diminished, whereas TBA-rs in the three biological materials was enhanced. Simultaneously, erythrocytes amount, hemoglobin level, hematocrit, and MCV were reduced. These results indicate that methanol in rats leads to the impairment of antioxidant mechanisms in the liver, erythrocytes, and blood serum.

Animals↗
PubMed1984

Cystine antagonism of the antibacterial action of lactoperoxidase-thiocyanate-hydrogen peroxide on Streptococcus agalactiae.

Cystine reduction in Streptococcus agalactiae, resulting in sulfhydryl formation, may account for antagonism of the antibacterial effect of lactoperoxidase-thiocyanate-hydrogen peroxide when cystine is present in excess of the amount needed for maximum growth. Accumulation of cystine by S. agalactiae and its reduction to form sulfhydryl compounds were demonstrated. The reduction of cystine appeared to occur by a couple reaction between glutathione reductase and glutathione-disulfide transhydrogenase activity, both of which were found in the supernatant fraction from cell homogenates. NADPH-specific glutathione reductase activity was found in the pellet and supernatant fractions from cell homogenates. Two sulfhydryls were formed for each mole of NADPH used during cystine reduction. The information presented offers a plausible explanation of how cystine, when present in excess of growth needs, may be reduced to generate sulfhydryl compounds which neutralize the antibacterial effect of lactoperoxidase-thiocyanate-hydrogen peroxide on S. agalactiae.

Cystine↗
PubMed1990

Sulfhydryl drug-induced eruption: a clinical and histological study.

Sulfhydryl drug-induced skin eruptions were studied clinically and histologically in 23 patients. In this study, tiopronin, D-penicillamine, captopril and gold sodium thiomalate were considered to be sulfhydryl drugs, because they have a thiol group or release sulfhydryl compounds. The clinical features included skin eruptions that were maculopapular, erythema multiforme-like, eczematous, psoriasis-like, seborrheic dermatitis-like, Gibert-like, lichen planus-like, and pemphigus-like. These clinical findings were reminiscent of the wide variety of eruptions seen in cutaneous graft-versus-host reactions (GVHR). Histologically, areas of vacuolation and eosinophilic necrosis with a satellite infiltrate of lymphoid cells were seen in the epidermis, and perivascular infiltrates were noted in the dermis. These findings were similar to the histological picture of cutaneous GVHR. In skin tests with sulfhydryl compounds, 19 out of 20 subjects showed positive reactions, and autoantibodies were found in 8 out of 12 subjects tested. Sulfhydryl drugs seem likely to induce immunologic changes in the host and to produce a distinctive reaction similar to that of cutaneous GVHR.

Adult↗
PubMed1988

Dietary inhibitors of mutagenesis and carcinogenesis.

Dietary inhibitors of mutagenesis and carcinogenesis are of particular interest because they may be useful for human cancer prevention. Several mutagenesis inhibitors have been demonstrated to be carcinogenesis inhibitors also, e.g., ellagic acid, palmitoleic acid, and N-acetylcysteine. This means that the search for mutagenesis inhibitors may be useful for discovering anticarcinogenic agents. Many mutagenesis inhibitors have been discovered by the use of short-term assays, particularly the Ames Salmonella test. This simple in vitro system has provided opportunities to elucidate the mechanisms of inhibition. The elucidation of the mechanism may allow us to infer the possible anticarcinogenic activity of the reagent. In this chapter, inhibitors of mutagenesis and carcinogenesis that can arise as components of diet have been reviewed. Most of the inhibitors have been demonstrated to be effective against a specific class of mutagens or carcinogens. Therefore, it may be argued that these inhibitors are antagonistic only to those particular agents. Here again, understanding of the mechanisms of these inhibitions is necessary for the assessment. Dietary inhibitors reviewed in this article include: (1) as inhibitors of mutagenesis: porphyllins, fatty acids, vitamins, polyphenols, and sulfhydryl compounds, (2) as inhibitors of carcinogenesis: vitamins A, E and C, ellagic acid, sulfhydryl compounds, fats, selenium, calcium, and fiber. Further studies in this area of science appear to help establish the recipe of a healthy diet.

Animals↗
PubMed2002

Efficacy of a whey protein concentrate on the inhibition of stomach ulcerative lesions caused by ethanol ingestion.

The purpose of this research was to test the ability of a whey protein concentrate (WPC) to inhibit gastric mucosal ulcerative lesions caused by oral administration to rats of absolute ethanol. Acute administration (single doses) of WPC resulted in 41% inhibition of the ulcerative lesion index (ULI), and 73% inhibition was obtained with repetitive doses. In a 10-days subchronic treatment study, the inhibition was 64%, all relative to a saline treatment (negative control). Alkylation of sulfhydryl compounds by subcutaneous injection of N-ethylmaleimide essentially eliminated the WPC protection. Treating the rats with an intraperitoneal injection of butathionine sulfoximine, which inhibits glutathione synthesis, reduced WPC protection to 35% and 52% for single and double doses, respectively. Taken as a whole, the results indicate that WPC does protect gastric mucosa from ethanol damage and that the protection depends on sulfhydryl compounds present in the WPC, including its capacity to stimulate glutathione synthesis.

Administration, Oral↗
PubMed1982

Thiol-dependent inhibition of RNA synthesis in vitro by acridines: structure-inhibition relationships.

In the presence of sulfhydryl compounds an anticancer drug, 1-nitro-9-aminoalkylacridine derivative, forms with DNA irreversible, probably covalent, complexes of decreased template properties. Five 9-substituted 1-nitro-9-aminoacridine derivatives of cytostatic activity show irreversible thiol-dependent inhibitory effects on the RNA synthesis in vitro system while equal inhibition is observed both in the presence and in the absence of dithiothreitol with biologically inactive analogues of nitrocrine. In the absence of sulfhydryl compounds the inhibition depends on the planarity of the acridine ring. Hence, both 1-nitro-9-aminoalkylacridine and tetrahydroacridine derivatives show low inhibitory effect.

Adenosine Triphosphate↗