Resonance Raman detection of the heme Fe(II)-NO/2-nitrovinyl in myoglobin

The six-coordinate heme Fe(II)-NO/2-nitrovinyl species in myoglobin has been detected and characterized by resonance Raman spectroscopy. The Fe(H)-(NO)-N-14 and N-15-O stretching frequencies of the ferrous heme nitrosyl/2-nitrovinyl species are detected at 560 and 1587 cm(-1), frequencies that are similar to those observed in the Mb heme Fe(II)-NO species. For the 2-nitrovinyl (C-a=CbNO2) moiety, which is formed upon H-abstraction from the -CbH2 group, the v(as)(NO2) is observed at 1322 cm(-1), the v(s)(NO2) at 1516 cm(-1) and the v(C-a=(CbNO2)-N-14)/v(C-a=(CbNO2)-N-15) at 1623/1615 cm(-1). The frequencies of the 2-nitrovinyl are largely unaffected by NO2-/NO binding to the heme Fe(II)/(III). The properties of the six-coordinate heme Fe(II)-NO/2-nitrovinyl species are compared to those of six-coordinate heme Fe(H)-NO and the five-coordinate heme Fe(II)-NO species isolated from meat products. (c) 2017 Elsevier B.V. All rights reserved.