• A comparison of a number of chemical features of actin prepared from cardiac and skeletal muscle has been undertaken in an attempt to evaluate the role that this contractile protein may play in determining specific physiological responses by the two types of muscle. Analyses of physicochemical properties 1 and amino acid compositions failed to reveal significant differences between these prot...

Peroxyacetyl nitrate reacts with the sulfhydryl groups of reduced glutathione. Thioester formation accounts for as much as 50% of the reacted sulfhydryl groups. As much as 60% of the reacted sulfhydryl groups can be accounted for as oxidized glutathione. The stoichiometry of the reaction is approximately 3 moles of sulfhydryl reacting per mole of peroxyacetyl nitrate, and this stoichiometry is ...

1. The mechanism of succinic dehydrogenase action was studied by means of inhibitors. 2. The enzyme is inhibited by a large number of diverse compounds whose only common denominator appears to be their ability to react with SH groups. These compounds include quinonoid structures, sulfhydryl reagents, sulfhydryl compounds, copper, zinc, selenite, and arsenite. 3. In contrast to the above inhibit...

The rates at which the sulfhydryl groups on each chain of hemoglobin fi4 react with N-ethylmaleimide and iodoacetate have been measured. The sulfhydryl group at position 93 reacts with both alkylating agents at approximately the same rate as normal liganded hemoglobin. The sulfhydryl group at position 112, which is not available in normal hemoglobin, reacts in hemoglobin f14 and does so much mo...

The rates at which the sulfhydryl groups on each chain of hemoglobin fi4 react with N-ethylmaleimide and iodoacetate have been measured. The sulfhydryl group at position 93 reacts with both alkylating agents at approximately the same rate as normal liganded hemoglobin. The sulfhydryl group at position 112, which is not available in normal hemoglobin, reacts in hemoglobin f14 and does so much mo...

A number of different enzymes are activated by certain reducing agents (e.g., KCN, H&S, cysteine, and reduced glutathione) and inactivated by oxidizing agents (e.g., K3Fe(CN)&, HzOz, and cystine). Under ideal conditions such inactivation is reversible by the addition of reducing agents (for a review of this subject cJ Hellerman (1937, 1939)). These results have been interpreted on the basis of ...

The yellow colored sulfhydryl reagent, iV-(4-dimethylamino-3,!%dinitrophenyl)maleimide, was used in the isolation of the peptide containing the reactive sulfhydryl group of chymopapain. Titration of cyanide-activated chymopapain B with p-chloromercuribenzoate at pH 4.6 indicated that there is a maximum of 1.4 moles of sulfhydryl per mole of the enzyme. Alkylation of half of the p-chloromercurib...

Free sulfhydryl and disulfide groups of an acid-soluble and acid-precipitable fraction and of isolated plasma membranes were quantified in fresh and stored human platelets. Fresh platelets contained 26.6 X 10 moles of total thiols including hee sulfhydryl and disulfide groups per iO cells. One-third of these thiols were present as disulfides. Acid-soluble thiols accounted for one-tenth of the t...