Oxidation and generation of hydrogen peroxide by thiol compounds in commonly used cell culture media

Many studies have examined the effects of thiol compounds upon cells in cul ture (e.g., upon signal transduction and regulation of gene expression), bu t few have considered how thiols can interact with cell culture media. A wi de range of thiols (cysteine, GSH, N-acetylcysteine, gamma -glutamylcystein e, cysteinylglycine, cysteamine, homocysteine) were found to interact with three commonly used cell culture media (RPMI, MEM, DMEM) to generate hydrog en peroxide with complex concentration-dependencies. Thiols added to these media rapidly disappeared, although less H2O2 was generated on a molar basi s than the amount of thiol lost. Studies on cellular effects of thiols, esp ecially those on redox regulation of gene expression or protein function, n eed to take into account that thiols are rapidly lost, and that their oxida tion generates H2O2, which can have multiple concentration-dependent effect s on cell metabolism. (C) 2001 Academic Press.