Sulfhydryl groups, cellular

However, since SMCC forms nonreversible thioether linkages with sulfhydryl groups, it only can be used in the preparation of immunotoxins if intact A-B toxins are employed in the conjugate. In such conjugates, the A chain still have the potential for reductive release from the B-chain subunit after cellular docking and internalization. Immunotoxins prepared with A-chain or single-subunit toxins will not display cytotoxicity if crosslinked with SMCC, since the crosslinker does not create cleavable disulfide bonds upon conjugation. 

Several mechanisms have been postulated to account for thallium s toxicity, including ligand formation with sulfhydryl groups of enzymes and transport proteins, inhibition of cellular respiration, interaction with riboflavin and riboflavin-based cofactors, alteration of the activity of K -dependent proteins, and disruption of intracellular calcium homeostasis. ... 

To determine how plants are injured, we studied changes in certain cellular constituents in plants exposed to ozone. The cells of these plants leak their contents and so it is probable that the initial damage is to cellular membranes. The normal functioning of these membranes depends on lipid constituents probably stabilized by sulfhydryl groups in associated proteins. 

Melarsoprol (frivalenf) and fryparsamide (penfavalent) are organic compounds confaining arsenic fhat bind to sulfhydryl groups in proteins, thereby affecting cellular structure and function. The action of arsenic is nonspe-... 

For example, the elucidation of the mechanism of action of the war gas Lewisite (Fig. 1.2), which involves interaction with cellular sulfhydryl groups, allowed the antidote, British anti-Lewisite or dimercaprol (Fig. 1.2), to be devised. Without the basic studies performed by Sir Rudolph Peters and his colleagues, an antidote would almost certainly not have been available for the victims of chemical warfare. 

Further structure-activity relationship (S AR) analyses of other cytoprotective enzyme inducers revealed the fact that all inducers can react with thiol/disulfide groups by alkylation, oxidoreduction, or thiol-disulfide interchange [Dinkova-Kostova and Talalay, 1999]. In fact, the capability of enzyme inducers to induce cytoprotective enzymes is well correlated with their reactivity with thiols. These results suggested a cellular sensor of inducers with highly reactive sulfhydryl groups, possibly reactive thiols in cysteine residues of a sensor protein. Nevertheless, the initial search for the sensor protein by using radioactively labeled inducers was not successful due to the abundance of thiol groups presented in many proteins in cells [Holtzclaw et al., 2004]. The molecular mechanism by which cytoprotective enzymes are induced remained to be elucidated. 

As described below, tolerance is an important consideration in the use of nitrates. While tolerance may be caused in part by a decrease in tissue sulfhydryl groups, it can be only partially prevented or reversed with a sulfhydryl-regenerating agent. The site of this cellular tolerance may be in the unknown reaction responsible for the release of nitric oxide from the nitrate, since other agents, eg, acetylcholine, that cause vasodilation via release of nitric oxide from endogenous substrates do not show cross tolerance with the nitrates. 

A. It reacts with sulfhydryl groups of various cellular substances, including enzymes. 

Witz G, Lawrie NJ, Amoruso MA, et al. 1987. Inhibition by reactive aldehydes of superoxide anion radical production from stimulated polymorphonuclear leukocytes and pulmonary alveolar macrophages Effects of cellular sulfhydryl groups and NADPH oxidase activity. Biochem Pharmacol 36 721-726. 

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