TY - JOUR
T1 - The heme environment of mouse neuroglobin. Evidence for the presence of two conformations of the heme pocket
AU - Couture, Manon
AU - Burmester, Thorsten
AU - Hankeln, Thomas
AU - Rousseau, Denis L.
PY - 2001/9/28
Y1 - 2001/9/28
N2 - Neuroglobin (Ngb) is a newly discovered oxygen-binding heme protein that is primarily expressed in the brain of humans and other vertebrates. To characterize the structure/function relationships of this new heme protein, we have used resonance Raman spectroscopy to determine the structure of the heme environment in Ngb from mice. In the Fe2+CO complex, two conformations of the Fe-CO unit are present, one of which arises from an open conformation of the heme pocket in which the CO is not interacting with any nearby residue, and the other arises from a closed conformation where a positively charged residue near the CO group stabilizes the complex. For the Fe2+O2 complex, we detect a single vFe-OO stretching mode at a frequency similar to that of oxymyoglobins and oxyhemoglobins of vertebrates (571 cm-1). Based on the Fe-C-O frequencies of the closed conformation of Ngb, a highly polar distal environment is indicated from which the O2 off-rate is predicted to be lower than that of Mb. In the absence of exogenous ligands, a heme pocket residue coordinates to the heme iron, forming a six-coordinate complex, thereby predicting a low on-rate for exogenous ligands. These structural properties of the heme pocket of Ngb are discussed with respect to its proposed in vivo oxygen delivery function.
AB - Neuroglobin (Ngb) is a newly discovered oxygen-binding heme protein that is primarily expressed in the brain of humans and other vertebrates. To characterize the structure/function relationships of this new heme protein, we have used resonance Raman spectroscopy to determine the structure of the heme environment in Ngb from mice. In the Fe2+CO complex, two conformations of the Fe-CO unit are present, one of which arises from an open conformation of the heme pocket in which the CO is not interacting with any nearby residue, and the other arises from a closed conformation where a positively charged residue near the CO group stabilizes the complex. For the Fe2+O2 complex, we detect a single vFe-OO stretching mode at a frequency similar to that of oxymyoglobins and oxyhemoglobins of vertebrates (571 cm-1). Based on the Fe-C-O frequencies of the closed conformation of Ngb, a highly polar distal environment is indicated from which the O2 off-rate is predicted to be lower than that of Mb. In the absence of exogenous ligands, a heme pocket residue coordinates to the heme iron, forming a six-coordinate complex, thereby predicting a low on-rate for exogenous ligands. These structural properties of the heme pocket of Ngb are discussed with respect to its proposed in vivo oxygen delivery function.
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U2 - 10.1074/jbc.M103907200
DO - 10.1074/jbc.M103907200
M3 - Article
C2 - 11473111
AN - SCOPUS:0035965286
SN - 0021-9258
VL - 276
SP - 36377
EP - 36382
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 39
ER -