Redox

About: Redox is a research topic. Over the lifetime, 26853 publications have been published within this topic receiving 862368 citations. The topic is also known as: reduction-oxidation & reduction-oxidation reaction.

Redox Regulation of the G1 to S Phase Transition in the Mouse Embryo Fibroblast Cell Cycle

Abstract: The hypothesis that intracellular oxidation/reduction (redox) reactions regulate the G(0)-G(1) to S-phase transition in the mouse embryonic fibroblast cell cycle was investigated Intracellular redox state was modulated with a thiol-antioxidant, N-acetyl-L-cysteine (NAC), and cell cycle progression was measured using BrdUrd pulse-chase and flow cytometric analysis Treatment with NAC for 12 h resulted in an approximately 6-fold increase in intracellular low-molecular-weight thiols and a decrease in the MFI of an oxidation-sensitive probe, dihydrofluorescein diacetate, indicating a shift in the intracellular redox state toward a more reducing environment NAC-induced alterations in redox state caused selective delays in progression from G(0)-G(1) to S phase in serum-starved cells that were serum stimulated to reenter the cell cycle as well as to inhibit progression from G(1) to S phase in asynchronous cultures with no significant alterations in S phase, and G(2)+M transits NAC treatment also showed a 70% decrease in cyclin D1 protein levels and a 3-4-fold increase in p27 protein levels, which correlated with decreased retinoblastoma protein phosphorylation Cells released from the NAC treatment showed a transient increase in dihydrofluorescein fluorescence and oxidized glutathione content between 0 and 8 h after release, indicating a shift in intracellular redox state to a more oxidizing environment These changes in redox state were followed by an increase in cyclin D1, a decrease in p27, retinoblastoma protein hyperphosphorylation and subsequent entry into S phase by 8-12 h after the removal of NAC These results support the hypothesis that a redox cycle within the mammalian cell cycle might provide a mechanistic link between the metabolic processes early in G(1) and the activation of G(1)-regulatory proteins in preparation for the entry of cells into S phase

Single electron transfer and nucleophilic substitution

Abstract: Publisher Summary This chapter discusses single electron transfer and nucleophilic substitution. The SRNl reaction appears as a reaction in which single electron transfer plays a pre-eminent role but is by no means a single elementary step. A different problem is that of the possible involvement of single electron transfer in reactions that are not catalyzed by electron injection (or removal). A typical example of such processes is another substitution reaction—namely, the SN2 reaction. The chapter discusses the reactions in which electron transfer is associated with the breaking of a bond but in which either no bond formation occurs or, if it does, it takes place in aseparated step. There are a number of cases where “true” SN2 mechanisms (in which the bond-breaking and bond-formation steps are concerted) do occur, even with nucleophiles that are members of reversible one-electron reversible redox couples.

Direct evidence of charge separation in a metal–organic framework: efficient and selective photocatalytic oxidative coupling of amines via charge and energy transfer

Abstract: The selective aerobic oxidative coupling of amines under mild conditions is an important laboratory and commercial procedure yet a great challenge. In this work, a porphyrinic metal–organic framework, PCN-222, was employed to catalyze the reaction. Upon visible light irradiation, the semiconductor-like behavior of PCN-222 initiates charge separation, evidently generating oxygen-centered active sites in Zr-oxo clusters indicated by enhanced porphyrin π-cation radical signals. The photogenerated electrons and holes further activate oxygen and amines, respectively, to give the corresponding redox products, both of which have been detected for the first time. The porphyrin motifs generate singlet oxygen based on energy transfer to further promote the reaction. As a result, PCN-222 exhibits excellent photocatalytic activity, selectivity and recyclability, far superior to its organic counterpart, for the reaction under ambient conditions via combined energy and charge transfer.