γ-Radiolysis of disulfides in aqueous solution. II. <scp>D</scp>-Penicillamine disulfide

Purdie, J. W.

doi:10.1139/v69-162

Cited by 11 publications

(5 citation statements)

References 15 publications

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“…Samples for product analysis were acidified and run as soon as possible on a Technicon amino acid analyzer, with care being taken to exclude air (16 …”

Section: Methodsmentioning

confidence: 99%

“…It appears that trisulfides are formed by more than one pathway. Trisulfides were also obtained in high yield by radiolysis of penicillamine disulfide and cysteine -penicillamine disulfide (16). If RSradicals of penicillamine react with protein disulfide bridges with resultant formation of trisulfides, irreversible damage may be done.…”

Section: Build-up Of Rssr-in Rsh Solutionsmentioning

confidence: 99%

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The Pulse Radiolysis of Penicillamine and Penicillamine Disulfide in Aqueous Solution

Purdie¹,

Gillis²,

Klassen³

1973

Can. J. Chem.

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Aqueous solutions of penicillamine (RSH) and penicillamine disulfide (RSSR) have been pulse irradiated at several pH's and the ensuing reactions studied. The rate constant for the reaction of solvated electrons with penicillamine disulfide decreases from 7.3 × 10−9 M−1 s−1 at pH 7 to 0.8 × 109 M−1 s−1 at pH 10. The first-order rate constant for the decomposition of the resulting radical anion, RSSR−, increases from 1.77 × 106 s−1 at pH 7 to 6.5 × 106 s−1 at pH 10. Both of these pH effects are attributed to deprotonation of the two amino groups of the disulfide which have microscopic pK values of 7.9 and 8.5. The equilibrium constant for the reaction[Formula: see text]is (2.31 ± 0.2) × 102 M−1 at pH 8 but increases to 3.04 × 102 M−1 at pH 7 and decreases to 0.96 × 102 M−1 at pH 9. Measured from the kinetics of the build-up of RSSR−, k−2 = 1.83 × 106 s−1 at pH 8.Decay of RSSR− in the presence of RSH follows second-order kinetics at high dose rates and first-order kinetics at low dose rates. At high dose rates two second-order reactions[Formula: see text]appear to be involved with rate constants of 1.7 × 109 M−1 s−1 and 6.4 × 109 M−1 s−1 respectively at pH 8, At low dose rates the decay appears to be due to a pseudo first-order reaction between RSSR− and H2O, k ~ 2 × 103 s−1, with valine (RH) and penicillamine trisulfide (RSSR) as principal products. These products are obtained in similar yields by gamma radiolysis of penicillamine solutions. At pH 5, the thiyl radical decays by second-order kinetics, 2k = (2.85 ± 0.15) × 109 M−1 s−1.Studies of solutions containing penicillamine and methanol showed that penicillamine repairs methanol radicals very efficiently by hydrogen transfer. k = (1.1 ± 0.1) × 108M−1 s−1. The implications of the results for chemical radioprotection are discussed.

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“…Samples for product analysis were acidified and run as soon as possible on a Technicon amino acid analyzer, with care being taken to exclude air (16 …”

Section: Methodsmentioning

confidence: 99%

Section: Build-up Of Rssr-in Rsh Solutionsmentioning

confidence: 99%

The Pulse Radiolysis of Penicillamine and Penicillamine Disulfide in Aqueous Solution

Purdie¹,

Gillis²,

Klassen³

1973

Can. J. Chem.

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“…respectively, while penicillamine (PenSH) and p-hydroxyvaline (PenOH) were obtained from Koch-Light Laboratories. Penicillamine trisulphide (PenSSSPen) was prepared by the method described by Purdie (1969) and pencillamink acid (PenS03H) was prepared by the Borner (1965) method. All solutions were made using doubly distilled water, the final distillation from alkaline permanganate and the pH adjusted using H2S0,.…”

Section: Methodsmentioning

confidence: 99%

The Photolysis of Penicillamine Disulphide in Acidic Aqueous Solution

Grant¹,

Stewart²

1984

Photochem & Photobiology

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Quantum yields of penicillamine (PenSH), valine (PenH), p-hydroxyvalinc (PenOH), penicillamine trisulphide (PenSSSPen), ammonia, a keto acid and penicillamine sulphinic acid (PenS0,H) were determined in the 254 nm-photolysis of aqueous solutions of penicillamine disulphide (PenSSPen) at pH 1.8. Oxygenation of the PenSSPen solutions prior to irradiation had no effect on the yield of PenSH, but increased the yields of PenOH, ammonia, keto acid and oxyacids of sulphur and decreased the yields of PenSSSPen and PenH. Evidence was obtained that deamination of PenSSPen is initiated by Pen. radicals in deoxygenated and PenO,. radicals in oxygenated solutions. Flash photolysis was used to detect the PenSS' radical in irradiated PenSSPen solutions and to study its rate of decay. Comparison of the results of the investigation with those published for cystine indicate that substitution of the inethylene hydrogens in cystine by methyl groups leads to a substantial increase in the importance of photochemical C-S bond fission.

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“…Disulfides also produce thiyl radicals during irradiation through their It has been suggested that for disulfides such as cystine or penicill amine, reaction 30 may be quite important [33]. This reaction certainly operates for bis(t-butyl) disulfide in which the t-butyl fragment is relatively stable [71] and contributes to the spectrum of products produced during the Irradiation of cystine [363], penicillamine [364], and cystine-penicillamine mixed disulfide [365]. However, evidence from pulse radiolysis [367] and product analysis [336,337,338,363,364,365] experiments suggests that for many biologically relevant disulfides, reaction 29 predominates.…”

Section: B Thiols and Free Radical Reactionsmentioning

confidence: 99%

Chemical protection against ionizing radiation. Final report

Livesey¹,

Reed²,

Adamson³

1984

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Section II reviews the contributions of various natural factors which influence the inherent radiosensitivity of biological systems. Included in the list of these factors are water, oxygen, thiols, vitamins and antioxi-«• dants. Brief attention is given to the model describing competition between oxygen and natural radioprotective substances (principally, thiols) in deter mining the net cellular radiosensitivity. Several theories of the mechanism(s) of action of radioprotective drugs are described in Section III. These mechanisms include the production of hypoxia, detoxication of radiochemical reactive species, stabilization of the radiobiological target and the enhancement of damage repair processes. Section IV describes the current strategies for the treatment of radiation injury. Likely areas in which fruitful research might be performed are described in Section V. Appendices are devoted to lists of currently-funded research projects involving chemical radiation protection and a brief compendium of compounds which have been tested for radioprotective activity.

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γ-Radiolysis of disulfides in aqueous solution. II. D-Penicillamine disulfide

Cited by 11 publications

References 15 publications

The Pulse Radiolysis of Penicillamine and Penicillamine Disulfide in Aqueous Solution

The Pulse Radiolysis of Penicillamine and Penicillamine Disulfide in Aqueous Solution

The Photolysis of Penicillamine Disulphide in Acidic Aqueous Solution

Chemical protection against ionizing radiation. Final report

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