ESR studies of free radicals in solution. I. Oxidation of cysteine and related thiols with ceric ion

Rate Constants for Reaction of Hydrogen Atoms with Compounds of Biochemical Interest

“…The radioprotective properties of sulfur-containing compounds are certainly related to these very high rate constants. The high rates observed here can be explained only on the basis that the site of attack of H atoms is the sulfur atom itself, as is also suggested from studies on their reaction with OH using pulse radiolysis (17,18), product analysis (19)(20)(21), and esr (22). It can be concluded from Table IV presence of an NH3+ group in cysteine and cystine seems to have little effect on the rate constants of these compounds.…”

Radical damage to proteins studied by EPR spin-trapping techniques

“…iii) When similar experiments were carried out with Ce 4ϩ and glutathione in the presence of DEPMPO a strong isotropic signal was detected with parameters a N = 1.42, a H = 1.42, a P = 4.58 mT, characteristic of a thiyl adduct (data not shown), as might be expected from the well-known ability of Ce 4ϩ to oxidise the -SH function. 26,27 iv) On the other hand, reaction of Ce 4ϩ under similar conditions with lysozyme (Fig. 5a), which has no thiyl residue, led to the detection of a strong spectrum characteristic of an oxygencentred trapped radical, simulated (Fig.…”

S−S Bond Mesolysis in α,α‘-Dinaphthyl Disulfide Radical Anion Generated during γ-Radiolysis and Pulse Radiolysis in Organic Solution

“…The sulfur−sulfur bond plays an important role in the tertiary structure of polypeptides or proteins . Dialkyl or diaryl disulfides (RSSR, R = alkyl or aryl) behave as a radiation protection agent in biological systems as well as mercaptans (RSH) or thiyl radicals (RS • ). , The stationary-state radiation chemistry, − EPR investigations − and a large number of pulse radiolysis studies of cystine and related compounds − have been carried out in aqueous solution. These studies have been focused on the formation and decay of the disulfide radical anion (RSSR •- ) having a characteristic transient absorption with a maximum peak at 410 nm, 13a,− and a molar absorption coefficient of 9400 dm 3 mol -1 cm -1 at 410 nm 13b.…”