Tuning of the thermochemical and kinetic properties of ascorbate by its local environment: solution chemistry and biochemical implications.

ABSTRACT: Ascorbate (vitamin C) is a ubiquitous biological cofactor. While its aqueous solution chemistry has long been studied, many in vivo reactions of ascorbate occur in enzyme active sites or at membrane interfaces, which have varying local environments. This report shows that the rate and driving force of oxidations of two ascorbate derivatives by the TEMPO radical (2,2',6,6'-tetramethylpiperidin-1-oxyl) in acetonitrile are very sensitive to the presence of various additives. These reactions proceed by the transfer of a proton and an electron (a hydrogen atom), as is typical of biological ascorbate reactions. The measured rate and equilibrium constants vary substantially with added water or other polar solutes in acetonitrile solutions, indicating large shifts in the reducing power of ascorbat

SUBMITTER: Warren JJ 

PROVIDER: S-EPMC2921859 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature