Resonance Raman detection of the myoglobin nitrito heme Fe–O–NO/2-nitrovinyl species: implications for helix E-helix F interactions. Issue 5 (5th January 2015)

• Record Type: Journal Article
• Authors: Lambrou, Alexandra; Pinakoulaki, Eftychia
• Is Part Of: Physical chemistry chemical physics. Volume 17:Issue 5(2015)
• Page Start: 3841
• Page End: 3849
• Publication Date: 2015-01-05
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c4cp04352a
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : We present resonance Raman evidence for the formation of myoglobin nitrito heme Fe–O–NO/2-nitrovinyl and propose that the species we have detected at acidic pH is the myoglobin nitrous heme Fe–(H)O–NO/2-nitrovinyl complex. Abstract : The description of biological activity in heme proteins responsible for activating small molecules requires identification of ligand movement into the metal and non-metal binding sites. Mechanisms of nitrite reductase activity in globins are difficult to verify without the structures of the bound ligand, but we now have such information from resonance Raman spectroscopy on the myoglobin nitrito heme Fe–O–NO/2-nitrovinyl species in their natural environment rather than in crystals. Our results indicate that the formation of the nitrito heme Fe–O–NO/2-nitrovinyl species is pH-dependent. The conditions under which the nitrito heme Fe–O–NO/2-nitrovinyl species is generated strongly suggest that this form corresponds to an acid induced transformation. We propose that the movement of helices E and F at low pH results in the protonation of nitrito heme Fe–O–NO by His64 Nε –H(E) to form the nitrous heme Fe–O(H)–NO species.