43] Plasma protein sulfhydryl oxidation: Effect of lowmolecular weight thiols

Abstract

Publisher Summary This chapter describes the plasma protein sulfhydryl oxidation and discusses oxidative modification of sulfhydryl groups, particularly extracellular fluids, under various environmental oxidative stresses, including ozone (O 3 ), nitrogen dioxide (NO 2 ), cigarette smoke, and aldehydes contained in cigarette smoke. The ability of protein thiols to form mixed disulfides with low-molecular-weight thiols (especially GSH)—which is a reversible process—has hindered the evaluation of protective effects of thiols on proteins in situations of oxidative stress. Although the formation of mixed disulfides is often regarded as an indicator of oxidative damage to proteins because it is assayed in terms of –SH loss or loss of enzyme activity, this process may serve as a protective mechanism, preventing thiols from being oxidized irreversibly. The formation of mixed disulfides under situations of oxidative stress may, however, involve intermediate formation of thiyl radicals, which could induce radical damage to other locations in proteins. The chapter discusses possible protection against the modification of protein sulfhydryls by aerosol administration of low-molecular-weight thiols [such as GSH, cysteine, or dihydrolipoic acid (DHLA)].