Heme/O2/•NO Nitric Oxide Dioxygenase (NOD) Reactivity: Phenolic Nitration via a Putative Heme-Peroxynitrite Intermediate

摘要

An oxy-heme complex, the heme-superoxo species (tetrahydrofuran)(F8)Fe^III-(O2^·−) (>2) (F8 = anortho-difluoro substituted tetraarylporphyrinate), reacts with nitrogen monoxide (·NO; nitric oxide) to produce a nitrato-iron(III) compound (F8)Fe^III-(NO3⁻) (>3) (X-ray). The chemistry mimics the action of ·NO Dioxygenases (NODs), microbial and mammalian heme proteins which facilitate ·NO detoxification/homeostasis. A peroxynitrite intermediate complex is implicated; if 2,4-di-t-butylphenol is added prior to ·NO reaction with >2, o-nitration occurs giving 2,4-di-t-butyl-6-nitrophenol. The iron product is (F8)Fe^III-(OH) (>4). The results suggest that heme/O2/·NO chemistry may lead to peroxynitrite leakage and/or exogenous substrate oxidativeitrative reactivity.