Distinguishing Nitro vs Nitrito Coordination in Cytochrome c' Using Vibrational Spectroscopy and Density Functional Theory.

ABSTRACT: Nitrite coordination to heme cofactors is a key step in the anaerobic production of the signaling molecule nitric oxide (NO). An ambidentate ligand, nitrite has the potential to coordinate via the N- (nitro) or O- (nitrito) atoms in a manner that can direct its reactivity. Distinguishing nitro vs nitrito coordination, along with the influence of the surrounding protein, is therefore of particular interest. In this study, we probed Fe(III) heme-nitrite coordination in Alcaligenes xylosoxidans cytochrome c' (AXCP), an NO carrier that excludes anions in its native state but that readily binds nitrite (K_d ∼ 0.5 mM) following a distal Leu16 → Gly mutation to remove distal steric constraints. Room-temperature resonance Raman spectra (407 nm excitation) identify ν(Fe-NO₂), δ

SUBMITTER: Nilsson ZN 

PROVIDER: S-EPMC5677563 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature