Oxidative Hydrolysis of Phosphorus(v) Esters of Thiols by Peroxymonosulfate Ion. Reactions of Peroxymonosulfate Ion With Phosphorus(v) Esters of Thiols

BLASKÓ, ANDREI; Bunton, Clifford A.; Kumar, Anurag

doi:10.1002/(sici)1099-1395(199706)10:6<427::aid-poc900>3.3.co;2-y

Cited by 9 publications

(15 citation statements)

References 13 publications

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“…Phosphonothioates and related thio esters are oxidized by peroxy acids. 2 These reactions are slower than those of alkyl sulfides, 20b, 21 and MoO 2 2À 4 may react oxidatively with VX, although at present we have no evidence on this question. We used H 2 O 2 in our work, but peroxy-borates and carbonates and the urea-H 2 O 2 adduct are convenient solid precursors.…”

Section: Discussionmentioning

confidence: 63%

Oxidation of thioanisole by peroxomolybdate ions: direct oxygen transfer from tetraperoxomolybdate ion

Bunton¹,

Gillitt²

2001

J of Physical Organic Chem

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Addition of thioanisole (PhSMe) to Na 2 MoO 4 in dilute hydrogen peroxide at pH 9.4 rapidly quenches the absorbance of the tetraperoxo complex, MoO 2 2À 4 , which gradually regenerates as the PhSMe is oxidized to the sulfoxide. This direct oxygen transfer is followed by the decreasing absorbance of MoO 2 2À 4 at 452 nm. In dilute H 2 O 2 the MoO 2 2À 4 becomes a steady-state intermediate, and kinetics monitored by 1 H NMR spectroscopy allow estimation of the second-order rate constant for oxidation of PhSMe by MoOO 2 2À 3 and rate constants for interconversion of MoOO 2 2À 3 and MoOO 2 2À 4 . The steady-state approximation breaks down at higher [H 2 O 2 ], and with [H 2 O 2 ] = 2 M the MoOO 2 2À 3 and MoO 2 2À 4 are approximately in equilibrium; based on the rate constants of oxidation of PhSMe by MoOO 2 2À 3 and MoO 2 2À 4 and the related association equilibrium constant, the observed and predicted rate constants for the overall oxidation of PhSMe are similar.

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Section: Discussionmentioning

confidence: 63%

Oxidation of thioanisole by peroxomolybdate ions: direct oxygen transfer from tetraperoxomolybdate ion

Bunton¹,

Gillitt²

2001

J of Physical Organic Chem

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“…Cysteine reacts to form thioether linkages, whereas tagged peptides form a chemically distinct phosphate diester. This diester linkage is normally quite stable but it can be made to rapidly hydrolyze by oxidation of the sulfur atom (16,17). The resin is treated with the peroxide agent Oxone, resulting in oxidation of all sulfur atoms present (thiophosphate, cysteine, and methionine).…”

Section: Resultsmentioning

confidence: 99%

Covalent capture of kinase-specific phosphopeptides reveals Cdk1-cyclin B substrates

Blethrow

Glavy²,

Morgan³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

291

290

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We describe a method for rapid identification of protein kinase substrates. Cdk1 was engineered to accept an ATP analog that allows it to uniquely label its substrates with a bio-orthogonal phosphate analog tag. A highly specific, covalent capture-andrelease methodology was developed for rapid purification of tagged peptides derived from labeled substrate proteins. Application of this approach to the discovery of Cdk1-cyclin B substrates yielded identification of >70 substrates and phosphorylation sites. Many of these sites are known to be phosphorylated in vivo, but most of the proteins have not been characterized as Cdk1-cyclin B substrates. This approach has the potential to expand our understanding of kinase-substrate connections in signaling networks.P rotein kinases regulate a vast array of biological processes through phosphorylation of protein substrates. A comprehensive map of all phosphorylation sites and kinase-substrate pairs would greatly facilitate the study of signaling networks. This goal faces two fundamental challenges. First, all protein kinases use ATP as a cofactor to phosphorylate their targets, and thus the direct substrates of a single kinase cannot be easily traced in protein mixtures containing multiple kinases. Second, phosphorylation often occurs at low stoichiometry and on low-abundance proteins. This makes substrate and phosphorylation site identification very challenging. Powerful methods have been developed to address these dual problems (1, 2). Kinase-substrate pairs can be tested in multiplexed phosphorylation assays by using immobilized arrays of purified proteins. These high-throughput chip-based assays have the added benefit of presenting low-abundance proteins at easily detectable levels and have provided a first-generation map of protein phosphorylation in Saccharomyces cerevisiae (3). However, these assays do not currently allow identification of phosphorylation sites and have not been adapted to organisms with more complex proteomes. Prediction of high-likelihood kinase substrates can sometimes be achieved by using knowledge of the substrate sequence motif preferences of individual kinases, but only when these preferences are strong (4, 5). Finally, thousands of in vivo phosphorylation sites from metazoan organisms have been identified in proteomic screens (6-9), but for most of these sites the responsible upstream kinases remain unknown.We have demonstrated a chemical and genetic solution to the common use of ATP by all kinases. Our approach relies on engineering a kinase to accept unnatural ATP analogs by modification of the ATP-binding pocket (10, 11). The analogs are very poor substrates for wild-type kinases; thus, an analog-sensitive kinase (or as-kinase) can be used to specifically radiolabel its substrates in cell extracts while preserving important aspects of biological context, such as the integrity of protein complexes. Coupling this approach with the use of libraries of genetically encoded affinity-tagged proteins has facilitated identification of low-abundanc...

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“…For instance, hydrogen peroxide homolysis could initiate free radical reactions, but this seems unlikely in a basic aqueous medium. In the case of reaction with peroxy acids, the initial step in VX detoxification appears to be oxidation at sulfur followed by hydrolytic P-S cleavage, 24 but we expect the hydroperoxide anion to be more potent as a nucleophile under the relevant experimental conditions than as an oxidant. Finally, an S N 2 attack of the hydroperoxide nucleophile on the carbon of the thiomethyl ligand might be a concern were the computational model compound to be subjected to the experimental conditions; since this Figure 1.…”

Section: Introductionmentioning

confidence: 97%

Molecular orbital calculations on the P—S bond cleavage step in the hydroperoxidolysis of nerve agent VX

Patterson

Cramer

1998

J. Phys. Org. Chem.

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The P-S bond cleavage process in the hydroperoxidolysis of a model system for the nerve agent VX was studied using ab initio and semiempirical molecular orbital methods. Aqueous solvation effects were included through single-point calculations using the semiempirical SM5.2PD/A continuum solvation model and geometries optimized at the HF/MIDI! level of theory. The predominant pathway for P-S bond cleavage involves pseudorotation of a low-energy trigonal bipyramidal intermediate followed by apical ligand ejection. In aqueous solution, the free energy barriers for these processes are found to be 14.3 and 4.6 kcal mol À1 , respectively, with electronic energies calculated at the MP2/cc-pVDZ//HF/MIDI! level of theory. By comparison with another continuum model of solvation (PCM), it is concluded that the SM5.2PD/A model performs well even for hypervalent phosphorus species, in spite of not having included any such molecules in the model's parameterization set.

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Oxidative Hydrolysis of Phosphorus(v) Esters of Thiols by Peroxymonosulfate Ion. Reactions of Peroxymonosulfate Ion With Phosphorus(v) Esters of Thiols

Cited by 9 publications

References 13 publications

Oxidation of thioanisole by peroxomolybdate ions: direct oxygen transfer from tetraperoxomolybdate ion

Oxidation of thioanisole by peroxomolybdate ions: direct oxygen transfer from tetraperoxomolybdate ion

Covalent capture of kinase-specific phosphopeptides reveals Cdk1-cyclin B substrates

Molecular orbital calculations on the P—S bond cleavage step in the hydroperoxidolysis of nerve agent VX

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