Sulfhydryl groups mercury

Warfarin, diphenacoum, bromodiolone, flocoumafen, and brodiphacoum are examples Both alkyl and aryl mercury compounds can bind to sulfhydryl groups Have caused population declines in certain mollusks... 

Heavy metals with no known biological function, such as aluminum, arsenic, lead, and mercury, are nonessential metals.4-5 These metals are toxic because they can irreversibly bind to enzymes that require metal cofactors. Toxic metals readily bind to sulfhydryl groups of proteins.6-7 In fact,... 

Mercury interacts with sulfhydryl groups in vivo, inhibiting enzymes and altering cell membranes. The pattern of clinical intoxication from mercury depends to a great extent on the chemical form of the metal and the route and severity of exposure. 

Tolerance to heavy metals, specifically mercury and cadmium, has been associated with the induction of kidney metallothionein, a protein rich in sulfhydryl groups which protects by chelation (102). The synthetic antidote dimercaprol, introduced after World War I for arsenic-containing gases, works by a similar mechanism (103). 

The enzyme contains four sulfhydryl groups, and all four may be required for activity since inactivation parallels the decrease in SH content over the entire rate range (Figure 12). (A two-fold molar excess of p-mercuri-benzate was added to a sample of crystallized beef kidney... 

Weiner, I. M., and O. H. Muller Interference of Sulfhydryl Groups in Analysis of Urinary Mercury and its Elimination. Anal. Chem. 27, 149 (1955). 

Mercury. Mercury exerts its principle nephrotoxic effect on the membrane of the proximal tubule cell. In low concentrations, mercury binds to the sulfhydryl groups of membrane proteins and acts as a diuretic by inhibiting sodium reabsorption. Organomer-curial diuretics were introduced into clinical practice in the 1920s and were used... 

Literally hundreds of complex equilibria like this can be combined to model what happens to metals in aqueous systems. Numerous speciation models exist for this application that include all of the necessary equilibrium constants. Several of these models include surface complexation reactions that take place at the particle-water interface. Unlike the partitioning of hydrophobic organic contaminants into organic carbon, metals actually form ionic and covalent bonds with surface ligands such as sulfhydryl groups on metal sulfides and oxide groups on the hydrous oxides of manganese and iron. Metals also can be biotransformed to more toxic species (e.g., conversion of elemental mercury to methyl-mercury by anaerobic bacteria), less toxic species (oxidation of tributyl tin to elemental tin), or temporarily immobilized (e.g., via microbial reduction of sulfate to sulfide, which then precipitates as an insoluble metal sulfide mineral). 

The functional group of thiols is the sulfhydryl group, -SH. Thiols are also called mercaptans because of their reaction with mercury salts to form mercaptides. Thiols have intense, disagreeable odors. They are more acidic than alcohols and are easily oxidized to disulfides. 

Like cadmium, mercury(II) has a strong affinity for sulfhydryl groups in proteins, enzymes, hemoglobin, and serum albumin. Because of the abundance of sulfhydryl groups in active sites of many enzymes, it is difficult to establish exactly which enzymes are affected by mercury in biological systems. 

Boyer, P. D. Spectrophotometric study of the reaction of protein sulfhydryl groups with organic mercurials. J. Am. Chem. Soc. 76, 4331—4337 (1954). 

Chemical modification of soybean agglutinin by acetylation of its amino groups resulted in little loss of agglutinating activity, whereas the protein was quite sensitive to modification of its tyrosyl residues.547 Failure of the protein to react with 2-iodoacetamide or p-(chloro-mercuri)benzoate in 6 M urea confirmed that it was devoid of sulfhydryl groups. A metalloprotein containing151 Ca2+ and Mn2+, the soybean lectin is inactivated by Al3+, Fe3+, and Pb2+, whereas Mn2+, Ba2+, Mg2+, Ag+, Li+, and K+ are without effect.532... 

Thietane is a superior inhibitor of corrosion of iron in 10% hydrochloric acid and its effectiveness is said to be due to partial polymerization on the surface of the iron. Addition of chloride ion reduces the inhibition, possibly by inducing ringopening with the formation of sulfhydryl groups. The cyclic sulfide also has been considered as an odorant for natural gas and its absorption by organic soil and clay have been determined. Stabilization of methylchloroform and trichloroethylene by thietane, 2-methylthietane, 3-hydroxythietane, and two spirothietane derivatives has been claimed. Phosphorus and tin derivatives of 3,3-bis-hydroxy-methylthie-tane are reported to be light stabilizers for poly(vinyl chloride), and the dibutyl-tin derivative is a catalyst for the polymerization of aliphatic isocyanates. Mercury and zinc compounds derived from phenylmercury or phenylzinc hydroxide and 3-... 

A particularly reactive sulfhydryl group (or groups) on the phosphate transporter react with relatively low concentrations of maleimide derivatives and organic mercurials to inhibit the function of the transporter [17]. This sulfhydryl group is probably near, or a part of, the substrate binding site because phosphate protects the carrier activity from inhibition by A-ethylmaleimide. Fonyo has written a comprehensive review on the subject of sulfhydryl sensitivity of the phosphate carrier and its implications concerning the mechanism of transport [192]. 

After inhalation, 70-80% of metallic vapor is retained and absorbed. Little is taken up in the gastrointestinal tract, and less than 10% is absorbed. In the body, it is oxidized to mercuric mercury, which binds to reduced sulfhydryl groups. The kidney is the main depository following exposure to both metallic and mercuric mercury. In addition to other organs, it passes into the brain and fetus. 

Not much is known about the toxic effects of ethylmercury and most toxicologists have assumed that the toxic changes would be similar to that caused by methylmercury. These alterations in turn are very complex and depend on duration of exposure, dose, and the age of the individual. Mercury salts have a strong affinity for sulfhydryl groups and this is likely to play a role in effecting their neurotoxicity. Some in vitro studies indicate that oxidative stress leading to lipid peroxidation and DNA damage may also underlie the mechanism of toxicity. 

A pollutant may combine with the active site or sites of an enzyme thus inactivating it. For example, a heavy metal such as mercury, lead, or cadmium can attach itself to the thiol or sulfhydryl (SH) group on an enzyme molecule, forming a covalent bond with the sulfur atom. This will lead to inactivation of the enzyme if the sulfhydryl group... 

Once absorbed, metallic and inorganic mercury enter an oxidation-reduction cycle. Metallic mercury is oxidized to the divalent inorganic cation in the red blood cells and lungs of humans and animals. Evidence from animal studies suggests that the liver is an additional site of oxidation. Absorbed divalent cation from exposure to mercuric compounds can, in turn, be reduced to the metallic or monovalent form and released as exhaled metallic mercury vapor. In the presence of protein sulfhydryl groups, mercurous mercury (Hg+) disproportionates to one divalent cation (Hg+2) and one molecule at the zero oxidation state (Hg°). The conversion of methylmercury or phenylmercury into divalent inorganic mercury can probably occur soon after absorption, also feeding into the oxidation-reduction pathway. 

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