416. New syntheses of disulphides from Bunte salts

Milligan, Brian; Swan, JM

doi:10.1039/jr9620002172

Cited by 32 publications

(19 citation statements)

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“…Fully reduced CstR or CstR modified with tetrathionate (S 4 O 6 2− ) as a disulfide control 42 (Table S2), SeO 3 2− or TeO 3 2− was titrated into a solution containing fluorescently-labeled cst OP1 under strictly anaerobic conditions (Fig. 5A).…”

Section: Resultsmentioning

confidence: 99%

Selenite and tellurite form mixed seleno- and tellurotrisulfides with CstR from Staphylococcus aureus

2013

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Staphylococcus aureus CstR (CsoR-like sulfur transferase repressor) is a member of the CsoR family of transition metal sensing metalloregulatory proteins. Unlike CsoR, CstR does not form a stable complex with transition metals but instead reacts with sulfite to form a mixture of di- and trisulfide species, CstR2(RS-SR′) and CstR2(RS-S-SR′)n, n = 1 or 2, respectively. Here, we investigate if CstR performs similar chemistry with related chalcogen oxyanions selenite and tellurite. In this work we show by high resolution tandem mass spectrometry that CstR is readily modified by selenite (SeO32−) or tellurite (TeO32−) to form a mixture of intersubunit disulfides and selenotrisulfides or tellurotrisulfides, respectively, between Cys31 and Cys60′. Analogous studies with S. aureus CsoR reveals no reaction with selenite and minimal reaction with tellurite. All cross-linked forms of CstR exhibit reduced DNA binding affinity. We show that Cys31 initiates the reaction with sulfite through the formation of S-sulfocysteine (RS-SO32−) and Cys60 is required to fully derivatize CstR to CstR2(RS-SR′) and CstR2(RS-S-SR′). The modification of Cys31 also drives an allosteric switch that negatively regulates DNA binding while derivatization of Cys60 alone has no effect on DNA binding. These results highlight the differences between CstRs and CsoRs in chemical reactivity and metal ion selectivity and establish Cys31 as the functionally important cysteine residue in CstRs.

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Section: Resultsmentioning

confidence: 99%

Selenite and tellurite form mixed seleno- and tellurotrisulfides with CstR from Staphylococcus aureus

2013

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“…2- [21] was treated with KI [24] to give the 1,2,5,6-tetrathiocin derivative L 2 , i.e., the disulfide form of L, in reasonable yield. Reduction of L 2 Figure 1 and Table S1 and Figure S1 in the Supporting Information).…”

Section: Synthesis and Properties Of Dithiol-containing Bulky Acylamimentioning

confidence: 99%

Unexpected Reaction Promoted by NH+···O=Mo Hydrogen Bonds in Nonpolar Solvents

et al. 2016

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“…The attack of thiosulphate ion on alkyl bromides, in 30y0 v / v ethanol-water solvent, to yield S-alkyl thiosulphates, known as Bunte salts (12), is one such group of reactions, and may be represented by the equation…”

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Secondary Kinetic Isotope Effects in Bimolecular Nucleophilic Substitutions: I. Deuterium Effects in the Bunte Salt Reaction

Leffek¹

1964

Can. J. Chem.

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'The secondary deuterium isotope effects have been measured for the reaction between sodium thiosulphate and a-deuterated methyl, ethyl, and n-propyl bromide, and also for 3-and ydeutcrated n-propyl bromide, in aqueous ethanol solvent. The a-deuterium isotopic rate ratios ( k a / k~) are all greater than unity. These unexpected results are discussed with respect to the suggested use of the a-deuterium isotope effect as a test of mechanism in nucleophilic substitutions.There are many examples in the literature of changes in the rates of nucleophilic substitutions when some of the hydrogen atoms of the reactant, which are not directly involved in the reaction, are replaced by deuterium (1-5). However, nearly all of these examples pertain to Sxl-type solvolytic reactions. Of the binlolecular reactions studied, Inany are solvolyses in water which show regular changes of isotope effect with changes of alkyl group and the site deuterated (6-9) ; I ery few isotope effects have been measured in non-solvolytic SN2 reactions (10, 11). I t is not known whether the regularities found in the solvolytic reactions are general for all biniolecular suhstitutioris; hence, the present investigation is part of a program of systematic study of secondary deuterium isotope effects in non-solvolytic bimolecular substitutions.Since the known isotope effects in this type of substitutio~l are small (11), it is necessary t o choose reactions for study which allow the precise determination of their rate constants. The attack of thiosulphate ion on alkyl bromides, in 30y0 v / v ethanol-water solvent, to yield S-alkyl thiosulphates, known as Bunte salts (12), is one such group of reactions, and may be represented by the equationThe unreacted sodium thiosulphate call be estinlated quite accurately by titration with standard iodine solution.H a~n m e t t and co-workers (13, 14) made a careful investigation of this reaction in their study of the changes which occur in the enthalpy and entropy of activation with structure of the alkyl group. They used an acetate buffer to avoid decomposition of thiosulphate ion in an acidic medium which could result from solvolysis of the alkyl bromide to give hydrobromic acid and an alcohol (or ether). The rate of acetate ion attack on the alkyl bromide was found t o be ~legligibly slow under the conditions of reaction. For the straightchain alkyl bro~uides, the rate of solvolysis was too slow to necessitate correction of the observed rate constants of the thiosulphate reaction.Subsequently, Bevan and Monk showed that Hainmett's rate constants for the reaction of sodium thiosulphate with n-propyl bromide in 50% v / v ethanol-water solvent, calculated using stoichiometric rnolarities of thiosulphate, are not the true rate constants

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416. New syntheses of disulphides from Bunte salts

Cited by 32 publications

References 0 publications

Selenite and tellurite form mixed seleno- and tellurotrisulfides with CstR from Staphylococcus aureus

Selenite and tellurite form mixed seleno- and tellurotrisulfides with CstR from Staphylococcus aureus

Unexpected Reaction Promoted by NH+···O=Mo Hydrogen Bonds in Nonpolar Solvents

Secondary Kinetic Isotope Effects in Bimolecular Nucleophilic Substitutions: I. Deuterium Effects in the Bunte Salt Reaction

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