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PubMed2001

Redox equilibrium between guanyl radicals and thiocyanate influences base damage yields in gamma irradiated plasmid DNA. Estimation of the reduction potential of guanyl radicals in plasmid DNA in aqueous solution at physiological ionic strength.

PURPOSE: Gamma irradiation of an aqueous solution containing thiocyanate ions produces the strongly oxidizing intermediate (SCN)2*-. Reaction of this species with plasmid DNA produces damage that is revealed as strand breaks after incubation with the Escherichia coli base excision repair endonuclease formamidopyrimidine-DNA N-glycosylase (FPG). It has been previously reported that the yield of damage is highly sensitive to the experimental conditions, leading to the suspicion that electron transfer between DNA and (SCN)2*- is reversible. In principle this makes it possible to determine the oxidation potential for plasmid DNA (more formally the reduction potential of one-electron oxidized plasmid DNA), a fundamental parameter describing the reactivity of DNA towards electron transfer reactions. MATERIALS AND METHODS: Aqueous solutions of plasmid DNA and thiocyanate ions were subjected to 137Cs gamma-irradiation. After irradiation, the plasmid was incubated with the E. coli base excision repair endonuclease formamidopyrimidine-DNA N-glycosylase (FPG). The yield of this damage was quantified by using agarose gel electrophoresis to identify the fraction of the plasmid population that contains strand breaks. RESULTS: The yield of FPG-sensitive sites decreases with increasing thiocyanate concentration, decreasing DNA concentration, and increasing dose rate. By making some simple assumptions about the chemical reactions that produce DNA damage, it is possible to derive a quantitative mathematical model for the yield of FPG-sensitive sites. A good agreement was found between this model and the experimental observations over a wide range of conditions (thiocyanate concentrations, DNA concentrations, and dose rates that vary by 20-, 40-, and 150-fold respectively). CONCLUSIONS: It was possible to assign a value to the equilibrium constant for the one electron transfer reaction between the two radical species (SCN)2*- and DNA-G*+. This leads to an estimate of the reduction potential at pH 7 for the couple DNA G*+/DNA of E7 = +1.39+/-0.01V.

DNA↗
PubMedDate not supplied

A simple and rapid method for the determination of thiocyanate in serum.

Studies were performed to evaluate ultrafiltration as a means for isolating thiocyanate from serum prior to its colorimetric determination as a ferric chloride complex. Recovery of thiocyanate from serum was enhanced by addition of alkali prior to preparation of the ultrafiltrate, and averaged 96.8%. The reproducibility (CV) of test was 2.3%, within-day; and 3.3%, between-day. The colorimetric reaction was linear to 100 micrograms/mL. The method was tested by determining thiocyanate concentrations in samples collected from smoking and nonsmoking individuals. Thiocyanate concentrations in patient samples, collected after IV-infusion of nitroprusside, were scattered around those of the general population, and ranged from 0.3 to 20 micrograms/mL.

Colorimetry↗
PubMed2004

Smoking history and serum cotinine and thiocyanate concentrations as determinants of rheumatoid factor in non-rheumatoid subjects.

OBJECTIVES: Smoking is associated with false-positive rheumatoid factor (RF). We explored the dose-response relationship of this association, using smoking history and serum cotinine and thiocyanate concentrations as measures of tobacco exposure. METHODS: A total of 6947 men and women aged 30 yr or over and free of clinical arthritis were included in the Mini-Finland Health Survey carried out between 1978 and 1980. Detailed histories of smoking and RF (sensitized sheep cell agglutination test) were obtained in the basic examination. In 2000, serum cotinine and thiocyanate were determined from serum samples collected at baseline and stored at -20 degrees C. A cut-off point of 100 microg/l was used for serum cotinine and 10 micromol/l for thiocyanate to indicate active smoking. RESULTS: There was a close association between smoking and strongly positive RF. After adjustment for age, sex, coffee consumption and region, the odds ratios (95% confidence intervals in brackets) in current smokers and in those who had quit smoking were 3.94 (2.04-7.61) and 2.71 (1.33-5.53), respectively, compared with those who had never smoked. Among current smokers, the intensity, duration or tertiles of pack-years of smoking were not related to RF. No relationship between serum cotinine or thiocyanate and RF positivity was observed within the subgroups of current smokers and those who had quit. Among those who reported that they had never smoked but who nevertheless had serum cotinine levels at least 100 microg/l, the adjusted odds ratio of strongly positive RF was 4.48 (1.48-13.50) compared with people who had never smoked and whose serum cotinine levels were less than 100 microg/l. CONCLUSIONS: The results are not in line with the hypothesis of a dose-response relationship between smoking exposure and RF positivity.

Adult↗
PubMed2002

Thioalkalivibrio thiocyanoxidans sp. nov. and Thioalkalivibrio paradoxus sp. nov., novel alkaliphilic, obligately autotrophic, sulfur-oxidizing bacteria capable of growth on thiocyanate, from soda lakes.

Nine strains of haloalkaliphilic, obligately autotrophic, sulfur-oxidizing bacteria able to grow with thiocyanate (SCN-) as the sole energy and nitrogen source were isolated from soda lakes in South-East Siberia, Kenya and Egypt after enrichment on sodium carbonate minerals buffered at pH 10 with thiocyanate as the substrate. The isolates fell into two groups that were substantially different in terms of cell morphology, growth parameters and the ability to oxidize carbon disulfide. The bacteria were able to oxidize sulfide, polysulfide, sulfur and tetrathionate, as well as thiocyanate. Two isolates belonged to an extremely halotolerant type growing in the presence of up to 4 M Na+. Cyanate (CNO-) was the main nitrogen-containing intermediate during thiocyanate degradation in both groups. According to DNA-DNA hybridization data and phylogenetic analysis, both groups of isolates belong to a recently described genus of haloalkaliphilic sulfur-oxidizing bacteria, i.e. Thioalkalivibrio, belonging to the gamma-Proteobacteria, in which where they represent two new species. The species name Thioalkalivibrio paradoxus (type strain ARh 1T = DSM 13531T = JCM 11367T) is proposed for the group with barrel-shaped cells, and the species name Thioalkalivibrio thiocyanoxidans (type strain ARh 2T, DSM 13532T = JCM 11368T) is proposed for the group with vibrio-shaped cells. The diagnosis of the genus Thioalkalivibrio is amended according to the new data.

DNA, Bacterial↗
PubMed2004

Anaerobic growth of the haloalkaliphilic denitrifying sulfur-oxidizing bacterium Thialkalivibrio thiocyanodenitrificans sp. nov. with thiocyanate.

Two strains of obligate chemolithoautotrophic sulfur-oxidizing bacteria were isolated from soda-lake sediments by enrichment culture with thiocyanate and nitrate at pH 9.9. The isolates were capable of growth with thiocyanate or thiosulfate as electron donor, either aerobically or anaerobically, and with nitrate or nitrite as electron acceptor. Cyanate was identified as an intermediate of thiocyanate oxidation, while sulfate, ammonia and dinitrogen gas were the final products. The anaerobic growth on thiocyanate plus nitrate was much slower (mu(max)=0.006 h(-1)) than on thiosulfate plus nitrate (mu(max)=0.02 h(-1)), while growth yields were similar (4.8 and 5.1 g protein mol(-1), respectively). On the basis of their phenotypic and genetic properties, strains ARhD 1(T) and ARhD 2 are described as a novel species of the genus Thialkalivibrio, with the highest similarity to Thialkalivibrio denitrificans. The name Thialkalivibrio thiocyanodenitrificans sp. nov. is proposed for this novel species.

Anaerobiosis↗
PubMed1979

Use of thiocyanic acid to form 2-thiohydantoins at the carboxyl terminus of proteins.

The chemistry of the formation of 2-thiohydantoins on the carboxyl terminal of peptides or proteins was investigated. It was found that thiocyanic acid was much more reactive for the formation of 2-thiohydantoins than were the thiocyanate salts. The physical reasons for this observation are explained. The kinetics of the reaction of a number of proteins, and some of their fragments, with thiocyanic acid were also determined. Simple and safe procedures for the preparation of anhydrous thiocyanic acid solutions were devised. The prospective application of these procedures to sequencing from the carboxyl terminal of a polypeptide is discussed.

Amines↗
PubMed1984

Diazotization and thiocyanate differentiate agonists from antagonists for the high- and low-affinity receptors of gamma-aminobutyric acid.

The differentiation of high- and low-affinity postsynaptic gamma-aminobutyric acid (GABA) receptors was examined in a washed cortical membrane preparation of the rat. The selective elimination of the high- and low-affinity GABA sites by the chaotropic anion thiocyanate and diazotization by p-diazobenzenesulfonic acid (DSA), respectively, offered two model systems for the separate sites. The [3H]GABA displacing potencies of some GABA agonists [GABA, 4,5,6,7-tetrahydro- isoxazole [4,5c]pyridine-3-ol (THIP), and muscimol] and antagonists [bicuculline methiodide (BCM), 3-alpha-hydroxy-16-imino-5 beta-17-aza-androstan-11-one (R-5135), and d-tubocurarine] and their slope factors were examined in these model systems and in control membranes. The displacing potency of the agonists was increased in the DSA-pretreated membranes and decreased in the presence of thiocyanate. The displacing potency of the antagonists was shifted in an opposite manner. The chaotropic effect of thiocyanate was reversible and not additive with the inhibitory effect of diazotization on the specific binding of GABA. Inhibition of specific GABA binding by pyridoxal-5-phosphate (PLP) could not be protected by GABA antagonists (BCM and R-5135) but only by agonists. The results can be interpreted in the framework of a dual (agonist-antagonist) receptor model, postulating a hydrophobic accessory site at the low-affinity GABA receptor. The effect of thiocyanate on the GABA receptor may result in the exposure of the hydrophobic accessory sites.

Androstanes↗
PubMed1993

Chemotaxis away from thiocyanic and isothiocyanic esters in Pseudomonas aeruginosa.

Negative chemotaxis, the movement of organisms away from chemicals, was investigated in Pseudomonas aeruginosa using a rapid videotape method. Digital image processing was used to detect changes in bacterial numbers near the mouth of a capillary containing a test chemical. P. aeruginosa was found to be repelled by thiocyanic and isothiocyanic esters including allyl isothiocyanate, ethyl thiocyanate, methyl isothiocyanate and methyl thiocyanate. Particularly, the movement of bacteria away from methyl thiocyanate was so drastic that bacterial numbers near the mouth of the capillary decreased by approximately 80% within 30 s after the start of observation. Mutant strains, fully motile but lacking positive chemotaxis, did not escape away from the esters, suggesting a common mechanism between positive and negative chemotaxes in this organism.

Chemotaxis↗
PubMed1972

Temperature dependence of chloride, bromide, iodide, thiocyanate and salicylate transport in human red cells.

1. The temperature dependence of the steady-state self-exchange of chloride between human red cells and a plasma-like electrolyte medium has been studied by measuring the rate of (36)Cl(-) efflux from radioactively labelled cells. Between 0 and 10 degrees C the rate increased by a factor of eight corresponding to an Arrhenius activation energy of 33 kcal/mole.2. The rate of chloride exchange decreased significantly in experiments where 95% of the chloride ions in cells and medium were replaced by other monovalent anions of a lyotropic series. The rate of chloride self-exchange was increasingly reduced by bromide, bicarbonate, nitrate, iodide, thiocyanate, and salicylate. The latter aromatic anion was by far the most potent inhibitor, reducing the rate of chloride self-exchange to 0.2% of the value found in a chloride medium.3. The temperature sensitivity of the chloride self-exchange was not affected significantly by the anionic inhibitors. The Arrhenius activation energies of chloride exchange were between 30 and 40 kcal/mole in the presence of the six inhibitory anions mentioned above.4. The rate of self-exchange of bromide, thiocyanate, and iodide between human red cells and media was determined after washing and labelling cells in media containing 120 mM bromide, thiocyanate, or iodide respectively. The rate of self-exchange of the three anions were 12, 3, and 0.4% of the rate of chloride self-exchange found in the chloride medium.5. The Arrhenius activation energies of the self-exchange of bromide, iodide, and thiocyanate were all between 29 and 37 kcal/mole, the same magnitude as found for the self-exchange of chloride.6. Although approximately 40% of the intracellular iodide and salicylate ions appeared to be adsorbed to intracellular proteins, the rate of tracer anion efflux followed first order kinetics until at least 98% of the intracellular anions had been exchanged.7. The self-exchange of salicylate across the human red cell membrane occurred by a different mechanism than the one utilized by the inorganic monovalent anions. The activation energy of salicylate exchange (13.2 kcal/mole) was significantly lower than that of inorganic anion exchange. Salicylate exchange increased with decreasing pH in contrast to the exchange of chloride, which decreases when pH is lowered.

Adsorption↗
PubMed1978

Lactoperoxidase, peroxide, thiocyanate antimicrobial system: correlation of sulfhydryl oxidation with antimicrobial action.

The antimicrobial activity of the lactoperoxidase, peroxide, thiocyanate system against Escherichia coli was directly related to the oxidation of bacterial sulfhydryls. Lactoperoxidase catalyzed the oxidation of thiocyanate, which resulted in the accumulation of hypothiocyanite ion, OSCN-. A portion of the bacterial sulfhydryls were oxidized by OSCN- to yield sulfenic acid and sulfenyl thiocyanate derivatives. The remaining sulfhydryls were not oxidized, although OSCN- was present in large excess. The oxidation of sulfhydryls to sulfenyl derivatives inhibited bacterial respiration. This inhibition could be reversed by adding sulfhydryl compounds to reduce the sulfenyl derivatives and the excess OSCN-. Also, this inhibition could be reversed by washing the cells so as to remove the excess unreacted OSCN-. After washing, the bacteria underwent a time-dependent recovery of their sulfhydryl content. This recovery resulted in recovery of the ability to respire. The inhibited cells were viable if diluted and plated shortly after the incubation with the lactoperoxidase, peroxide, thiocyanate system. On the other hand, long-term incubation in the presence of the excess OSCN- resulted in loss of viability. Also, the inhibition of respiration became irreversible. During this long-term incubation, the excess OSCN- was consumed and the sulfenyl derivatives disappeared.

Dithiothreitol↗
PubMed1980

Bactericidal effect of hydrogen peroxide is prevented by the lactoperoxidase-thiocyanate system under anaerobic conditions.

Streptococcus sanguis and Peptostreptococcus anaerobius were exposed to various combinations of the components of the lactoperoxidase-thiocyanate-hydrogen peroxide system. The bactericidal effect of hydrogen peroxide was prevented under anaerobic conditions by lactoperoxidase together with thiocyanate, but not by lactoperoxidase or thiocyanate alone. Thiocyanate was effective already at a molar ratio to hydrogen peroxide of 1:100.

Anaerobiosis↗
PubMed1982

Blood carboxyhaemoglobin, plasma thiocyanate, and cigarette consumption: implications for epidemiological studies in smokers.

Carboxyhaemoglobin and plasma thiocyanate concentrations were found to be significantly correlated with self-reported daily cigarette consumption in 360 smokers (r = 0.416 and 0.412 respectively; p less than 0.001). The extent to which inhalation patterns affected the intake of cigarette smoke constituents was determined from the partial correlation between carboxyhaemoglobin and plasma thiocyanate concentrations after the number of cigarettes smoke per day had been allowed for (r = 0.48). Thus 23% of the variation in carboxyhaemoglobin and thiocyanate concentrations was accounted for by the was a cigarette was smoked and a further 21% by the number smoked a day. Furthermore, the relation between carboxyhaemoglobin or plasma thiocyanate and daily cigarette consumption was not linear but reached an asymptote at consumption rates above 25 cigarettes a day. These results suggest that by itself daily cigarette consumption will not identify those smokers most at risk and will also underestimate and dose-response relationship between smoking and selected diseases.

Carboxyhemoglobin↗
PubMedDate not supplied

Concentration of thiocyanate and ionizable iodine in saliva of smokers and nonsmokers.

The concentration of thiocyanate and ionizable iodine was determined with saliva samples from two test groups, smokers (N = 27) and nonsmokers (N = 92). The contents of both ions were also compared as to sex and the amount of cigarettes smoked. The concentrations of the ions studied were dependent on each other-the less iodine, the more thiocyanate in the samples. Females had significantly more iodine and less thiocyanate concentrations than males. Smoking had an increasing effect on the concentration of thiocyanate and a decreasing effect on the content of ionizable iodine in the saliva of the volunteers. The lower amount of iodine ions in the saliva of smokers may restrict the nonthyroidal metabolism of the thyroid hormone in humans.

Adolescent↗
PubMed1978

Correlation between per cent discharge of thiocyanate test and thyroid functions in patients with Hashimoto's disease.

The thiocyanate test was carried out in 18 patients with Hashimoto's disease. Thiocyanate was given orally several hours after the administration of tracer doses of 131I when the thyroid counts seemed to have reached a plateau. The per cent discharge of thiocyanate test was significantly higher in the groups with lower level of T4 (less than 5.5 microgram/100 ml), RSH (less than 25.5%) and BMR (less than +2.5%), and higher levels of TSH (greater than 10.0 muU/ml). A chi-square (chi2) test with Yates correction led to chi2 = 3.56 (1 df) with P = 0.06 (per cent discharge vs T4, RSU, BMR and TSH). Then the per cent thiocyanate discharge was increased with the degree of hypothyroidism in patients with Hashimoto's disease. The correlation between the per cent discharge and 131I 24 h uptake was not significant. It was apparent that the iodide concentration mechanism was present even in the severe hypothyroid stage of Hashimoto's disease. This disproportion between the uptake of iodide and the iodide organification may result in the increase in unbound iodide. It is concluded that the hypothyroidism in Hashimoto's disease may not be caused by a defect in iodide organification, even if it correlated to the degree of hypothyroidism.

Adult↗
PubMed2001

Kinetic spectrophotometric determination of thiocyanate based on its inhibitory effect on the oxidation of methyl red by bromate.

A kinetic spectrophotometric method for measuring thiocyanate is described. The proposed method is based on the inhibitory effect of thiocyanate on the oxidation of Methyl Red by bromate in the presence of nitrite, which was monitored at 520 nm. The variables affecting the rate of the reaction were investigated and the optimum conditions were established. Thiocyanate can be measured in the range of 0.05-1.1 microg ml(-1) with a detection limit of 0.025 microg ml(-1). This method has been used to determine trace thiocyanate in urine and tap water samples.

Absorption↗
PubMed1999

Effect of thiocyanate induced hypothyroidism on 5'deiodinase activity and T3 receptors in developing rat brain.

Experiments were performed in weaning rats to understand the influence of thiocyanate, an hydrolytic product of glucosinolates present in foods, on the generation of T3 in situ by type II 5'deiodinase and the binding of 125I T3 to specific nuclear receptors in developing brain. Feeding of thiocyanate through gestation and lactation resulted in an increase in type II 5'deiodinase activity in cerebrum, cerebellum and brainstem of the 21 day old pups compared to controls. Hypothyroidism induced by thiocyanate further resulted in augmentation of the maximum binding capacity of receptors in the cerebrum of the weaning pups. Affinity constants for binding of 125I T3 were however, unaltered. Increase in type II 5'deiodinase activity and the number of binding sites point to an adaptive increase in response to thiocyanate induced hypothyroidism to maintain the cellular T3 levels within a narrow limit.

Animals↗
PubMed2003

[Study of molybdenum (V) thiocyanate complexes in the acidic aqueous solution].

In this paper, the Mo(V)-thiocyanate complexing reaction in the acidic aqueous solution without surfactant or organic solvent was studied. It was found that the Mo(V)-thiocyanate complexes could be stable for 4 h at least in the 50 mL solution containing 7.5 mL H2SO4 (1:1), 4 mL HClO4 (1:1), 3 mg Fe2+ and 4 mL vitamin C (6%). The absorption spectrum of Mo(V)-thiocyanate complexes under this condition was studied, a peak of 460 nm was found and the maximal molar absorption coefficient was determined to be 1.02 x 10(4). The reaction mechanism of the Mo(V)-thiocyanate complexes was determined to be a three-grade complexing reaction by using the equilibrium movement method. Meanwhile, the stable constants of all kinds of grades complexes was determined by the [symbol: see text] method to be beta 1 = 15.63, beta 2 = 174.4 and beta 3 = 1,502, and the corresponding molar absorption coefficients were delta epsilon 1 = 8,957, delta epsilon 2 = 9,347 and delta epsilon 3 = 10,610, respectively.

Chelating Agents↗
PubMed1992

Problems of iodine and thiocyanate in domestic animals in goitrogenic areas of southern Poland.

High incidence of goitre in human together with low level of iodine in water and cow milk have been observed in Southern Poland (Table I). Therefore, iodine deficiency was considered as the only cause of goiter development. The correlation coefficient between iodine concentration in water and cow milk was r = 0.76 (Fig. 1) and indicate the possibility of iodine determination in milk instead of water. The iodine determination in milk reflects the level of iodine in water as well as in food, a negative correlation has been obtained between goitre incidence in human and iodine concentration in water (r = 0.43) (Fig. 2.). A low correlation coefficient suggest that iodine is not a solely factor responsible for goitre development. Studies on cows have indicated that thiocyanate may have effect on goitre development as well. There has been found higher concentration of thiocyanate (SCN) in blood plasma and in enlarged thyroids (Table II). Thiocyanate belongs to goitrogenic compounds and its main source are the plants of Brassica species widely cultivated in southern Poland. It has been found that cows fed with Brassica plants have high level of SCN both in blood and milk with no alteration of plasma iodine level. The transfer of iodine from plasma to milk is only slightly affected (Table III). The level of SCN in the thyroid depends on its plasma concentration; the calculated correlation coefficient is r = 0.88 (Fig. 3). Enhanced thyrotropin (TSH) secretion (during goitrogenesis) may be accompanied by increased accumulation of SCN in the thyroid (like iodide) and reduced oxidation to SO4 (unlike iodide) (Fig. 4). Therefore we postulated that TSH may be partly responsible for increased SCN level in goitrous thyroids. The question arise whether increased ingestion of SCN does really potentiate iodine deficiency and goitrogenic process in animals breeding in southern Poland. For explanation some additionally experiments were performed on laboratory animals. It have been observed that enhanced level of plasma SCN following feeding with Brassica plants increased proportionally the goitrogenic action as well as the accumulation of 131J by the thyroid and its conversion into organic form (Fig. 5). The latter data was confirmed by positive correlation between thyroxine and plasma SCN levels in sheep (r = 0.49), (Fig. 6) Thiocyanate like other monovalent anions suppress goitrogenic effect of propylthiouracil. However, anti-goitrogenic properties of SCN depends on normal iodine ingestion (Fig. 7).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗