Several reagents have been employed to determine the role of the thiol groups in fumarase. The nature of the reaction of these reagents indicates that the thiol groups are not associated with active site structures but are buried in a hydrophobic environment in the interior of the enzyme. Several observations are in accord with this view. The rate of reaction of the thiol groups is much slower ...

N-Ethylmaleimide (NEM) has been much used for the chemical modification of proteins, and it is usually assumed that reaction occurs specifically at the thiol groups of cysteinyl residues. However, NEM has been shown to react also with the acamino group of peptides and with the imidazole group of histidine (Smyth, Nagamatsu & Fruton, 1960), and with the a-amnino group of certain amino acids (Smy...

Development of easy, practical, and low-cost spectrophotometric methods is required for the selective determination of phenolic antioxidants in the presence of other similar substances. As electron transfer (ET)-based total antioxidant capacity (TAC) assays generally measure the reducing ability of antioxidant compounds, thiols and phenols cannot be differentiated since they are both responsive...

The dynamic nature of cell adhesion and detachment, which plays a critical role in a variety of physiological and pathological phenomena, still remains unclear. This motivates the pursuit of controllable manipulation of cell adhesion and detachment for a better understanding of cellular dynamics. Here we present an addressable, multifunctional, and reusable platform, termed the biological bread...

Stereoselective formal synthesis of (+)-allokainic acid was accomplished starting from L-glutamate by using a thiol-mediated acyl radical cyclization as a key step. The cyclization of a formylalkenoate proceeded in a highly diastereoselective manner to give trans-4,5-disubstituted pyrrolidin-3-one without the production of the cis-isomer. The pyrrolidinone was then converted into the establishe...

An asymmetric synthesis of the C(9)-C(25) spiroketal fragment of calyculin C is described. Key steps include two crotylation reactions using successively Brown's reagent and (Z)-crotyltrifluorosilane for the formation of the anti, anti, anti stereotetrad, ynone formation by a Pd-catalyzed coupling of a thiol ester with a terminal alkyne and a double intramolecular hetero-Michael addition for th...

A series of glycosyl hemiacetal derivatives have been transformed into thioglycosides and glycosyl thiols in a one-pot two-step reaction sequence mediated by Appel reagent (carbon tetrabromide and triphenylphosphine). 1,2-trans-Thioglycosides and β-glycosyl thiol derivatives were stereoselectively formed by the reaction of the in situ generated glycosyl bromides with thiols and sodium carbonotr...

A simple test for the determination of cystinuria and of aminoaciduria is described. The basisof the test is the color reaction between nitroprussideand thiol groups. The reagent is a dry mixture to which the urine samplesare applied. The ease of peformance of the test makes it ideal for use as a screening procedure. The reaction is nonspecific, and positive tests require further investigation ...

1. Seven unique carboxymethylcysteine-containing peptides have been isolated from tryptic digests of rabbit muscle aldolase carboxymethylated with iodo[2-(14)C]acetic acid in 8m-urea. These peptides have been characterized by amino acid and end-group analysis and their location within the cyanogen bromide cleavage fragments of the enzyme has been determined. 2. Reaction of native aldolase with ...