Cysteine plays structural roles in proteins and can also participate in electron transfer reactions, when some structural folds provide appropriated environments for stabilization of its sulfhydryl group in the anionic form, called thiolate (RS(-)). In contrast, sulfhydryl group of free cysteine has a relatively high pK(a) (8,5) and as a consequence is relatively inert for redox reaction in phy...

The reaction between iodoacetic acid and sulfhydryl compounds has received much attention in recent years. Dickens (1) has shown that this reaction proceeds with the formation of HI and the substitution of a carboxymethyl group for the hydrogen of the thiol group. Smythe (2) has measured the rate of reaction of iodoacetic acid with various sulfhydryl compounds by estimation of the carbon dioxid...

Duerre, John A. (University of North Dakota, Grand Forks), and Chris H. Miller. Cleavage of S-ribosyl-l-homocysteine by extracts from Escherichia coli. J. Bacteriol. 91:1210-1217. 1966.-Cell-free extracts prepared from Escherichia coli catalyze the cleavage of the thioether linkage of S-ribosylhomocysteine. One of the products has been identified as homocysteine by paper chromatography of the N...

The condensation of retinene(1) with opsin to form rhodopsin is optimal at pH about 6, a pH which favors the condensation of retinene(1) with sulfhydryl rather than with amino groups. The synthesis of rhodopsin, though unaffected by the less powerful sulfhydryl reagents, monoiodoacetic acid and its amide, is inhibited completely by p-chloromercuribenzoate (PCMB). This inhibition is reversed in ...

An overview of the literature concerning the effects of thimerosal is presented. Because of its antibacterial effect, thimerosal is used for a variety of practical purposes such as antiseptic and preservative. In biomedical studies, thimerosal is used as a sulfhydryl reagent, and as a calcium-mobilizing agent. The ability of thimerosal to act as a sulfhydryl group is related to the presence of ...

Absolute rate constants for the reaction of NADH with thiyl free radicals derived from various sulphur-containing compounds of biological significance were measured by using the technique of pulse radiolysis. These and related reactions with phenoxyl free radicals are believed to occur through one-electron-transfer processes. Further evidence comes from studies with deuterated NADH. The results...

When chicken liver dihydrofolate reductase reacts with an excess of sodium tetrathionate, 1 mol of thiosulfate becomes covalently attached to the single sulfhydryl group of the enzyme. The identity of the thiosulfate was established by obtaining 1:l binding independently with both innerand outer-labeled [36S]tetrathionate. The thiosulfate form of the enzyme has 5to 10-fold more activity than n...