Sulfhydryl inhibition

Coumarin, the lactone of o-hydroxycinnamic acid, and some of its derivatives have been isolated from many plant species 31). Thimann and Bonner 141) attributed the growth-inhibiting effects of coumarin to its action on enzyme sulfhydryl groups. Inhibitory effects of coumarin on Avena coleoptiles and pea stem sections could be overcome by 2,3-dimercaptopropanol (BAL). Coumarin has also been reported to disrupt mitosis 29,30). 

There are many ligands and group-specific reagents that have been demonstrated to alter the properties of H,K-ATPase, and which are not clinically useful. For example, there is a variety of chemicals that have been used in studies on structure-function relations of H,K-ATPase and that inhibit the enzyme in vitro by modification of its amino [49,67,158], sulfhydryl [95,165,166] or carboxyl groups [140]. 

Hu, M.-L., Dillard, C.J. and Tappel, A.L. (1988) Aurofhioglucose effect on sulfhydryls and glutathione-metabolizing enzymes in vivo inhibition of selenium-dependent glutathione peroxidase. Research Communications in Chemical Pathology and Pharmacology, 59,... 

Seiji, M.T., Yoshida, T., Itakura, H. and Irimajiri, T. (1969). Inhibition of melanin formation by sulfhydryl compounds. J. Invest. Dermatol. 52, 280-286. 

Inhibition by sulfhydryl reagents Sensitive Less sensitive Sensitive... 

Including EDTA in the final preparation inhibits metal-catalyzed oxidation of the sulfhydryl groups to disulfides. The modified peptide or protein should be used immediately to assure full sulfhydryl reactivity. 

Showdomycin inhibits synthesis of nucleic acid. Thiols, such as cysteine and glutathione (among other compounds), reverse this inhibition, and it is considered that the interaction of the maleimide moiety with sulfhydryl groups within the cell or in the membrane may be responsible for the selective inhibition of enzymes by show-... 

Intracellular and extracellular ROS activate tyrosine and serine-threonine kinases (i.e., the MAPK family members). Following TNF-a, TGF-f5 or EGF stimulation, intracellular ROS are generated which stimulate various signaling pathways [73], Tyrosine kinase receptors (e.g., EGF, PDGF and TGF-a) may be activated by ROS directly via protein sulfhydryl group modifications, or inhibition of phosphotyrosine phosphatases (PTPases) and subsequent receptor activation. The latter is possible as PTPases contain a redox-sensitive cysteine at their active site [78], and oxidation of protein sulfhydryl groups results in the inactivation of PTPases. 

---