The heme environment of mouse neuroglobin. Evidence for the presence of two conformations of the heme pocket.

摘要: Neuroglobin (Ngb) is a newly discovered oxygen-binding heme protein that primarily expressed in the brain of humans and other vertebrates. To characterize structure/function relationships this new protein, we have used resonance Raman spectroscopy to determine structure environment Ngb from mice. In Fe2+CO complex, two conformations Fe–CO unit are present, one which arises an open conformation pocket CO not interacting with any nearby residue, closed where positively charged residue near group stabilizes complex. For Fe2+O2 detect single νFe-OO stretching mode at frequency similar oxymyoglobins oxyhemoglobins vertebrates (571 cm−1). Based on Fe-C-O frequencies Ngb, highly polar distal indicated O2 off-rate predicted be lower than Mb. absence exogenous ligands, coordinates iron, forming six-coordinate thereby predicting low on-rate for ligands. These structural properties discussed respect its proposed vivo oxygen delivery function.