Radical energies and the regiochemistry of addition to heme groups. Methylperoxy and nitrite radical additions to the heme of horseradish peroxidase.

ABSTRACT: The heme of hemoproteins, as exemplified by horseradish peroxidase (HRP), can undergo additions at the meso carbons and/or vinyl groups of the electrophilic or radical species generated in the catalytic oxidation of halides, pseudohalides, carboxylic acids, aryl and alkyl hydrazines, and other substrates. The determinants of the regiospecificity of these reactions, however, are unclear. We report here modification of the heme of HRP by autocatalytically generated, low-energy NO2* and CH3OO* radicals. The NO2* radical adds regioselectively to the 4- over the 2-vinyl group but does not add to the meso positions. Reaction of HRP with tert-BuOOH does not lead to heme modification; however, reaction with the F152M mutant, in which the heme vinyls are more sterically accessible, results in conve

SUBMITTER: Wojciechowski G 

PROVIDER: S-EPMC2526285 | biostudies-literature | 2007 Feb

REPOSITORIES: biostudies-literature