Polymorphonuclear leukocytes (PMN) stimulated by high concentrations of the complement component C5A form cellular aggregates, and both the rate and degree of aggregation are influenced by changes in the PMN plasma membrane and cytoskeleton. Since sulfhydryls are important constituents of the plasma membrane and cytoskeleton, we investigated the effect of agents that oxidize and bind sulfhydryl...

Bovine cardiac troponin C (cTnC) contains 2 cysteine residues, Cys-35 located in the nonfunctional Ca2+-binding loop I and Cys-84 in the N-terminal segment of the central helix. We have studied the reactivity of Cys residues in cTnC with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) and 7-diethylamino-3-(4'-maleimidylphenyl)-4-methylcoumarin (CPM). The latter compound fluoresces only when reacted ...

The importance of two of the thiol groups of yeast triosephosphate dehydrogenase for its activity haa been shown by the abolition of activity and diphosphopyridine nucleotide binding by the addition of 2 equivalents of p-chloromercuribenzoate (PCMB) (1, 2). The reaction of methyl mercury nitrate with this enzyme has been found to be anomalous in the sense that this mercury compound, unlike PCMB...

A mixture of the carotenoid retinenel and the protein Qpsin, placed in the dark, reacts spontaneously to form the light-sensitive pigment of rod vision, rhodopsin (Wald and Brown, 1950). The nature of the binding between retinenel and opsin governs the conditions under which this synthesis occurs. Conversely the opening of the linkage between opsin and its chromophore as rhodopsin bleaches may ...

Many structurally diverse chemicals (e.g., acrylamide, 2,4-dithiobiuret, methylmercury) are electrophiles and cause synaptic dysfunction by unknown mechanisms. The purpose of this Forum review is to discuss the possibility that highly nucleophilic cysteine thiolate groups within catalytic triads of synaptic proteins represent specific and necessary targets for electrophilic neurotoxicants. Most...