TY - JOUR
T1 - Redox-induced structural dynamics of Fe-heme-ligand in myoglobin by X-ray Absorption Spectroscopy
AU - Della Longa, Stefano
AU - Arcovito, Alessandro
AU - Benfatto, Maurizio
AU - Congiu Castellano, Agostina
AU - Girasole, Marco
AU - Hazemann, Jean Louis
AU - Lo Bosco, Antonella
PY - 2003
Y1 - 2003
N2 - The Fe(III) --> Fe(II) reduction of the heme iron in aquomet-myoglobin, induced by x-rays at cryogenics temperatures, produces a thermally trapped nonequilibrium state in which a water molecule is still bound to the iron. Water dissociates at T > 160 K, when the protein can relax toward its new equilibrium, deoxy form. Synchrotron radiation x-ray absorption spectroscopy provides information on both the redox state and the Fe-heme structure. Owing to the development of a novel method to analyze the low-energy region of x-ray absorption spectroscopy, we obtain structural pictures of this photo-inducible, irreversible process, with 0.02-0.06-A accuracy, on the protein in solution as well as in crystal. After photo-reduction, the iron-proximal histidine bond is shortened by 0.15 A, a reinforcement that should destabilize the iron in-plane position favoring water dissociation. Moreover, we are able to get the distance of the water molecule even after dissociation from the iron, with a 0.16-A statistical error.
AB - The Fe(III) --> Fe(II) reduction of the heme iron in aquomet-myoglobin, induced by x-rays at cryogenics temperatures, produces a thermally trapped nonequilibrium state in which a water molecule is still bound to the iron. Water dissociates at T > 160 K, when the protein can relax toward its new equilibrium, deoxy form. Synchrotron radiation x-ray absorption spectroscopy provides information on both the redox state and the Fe-heme structure. Owing to the development of a novel method to analyze the low-energy region of x-ray absorption spectroscopy, we obtain structural pictures of this photo-inducible, irreversible process, with 0.02-0.06-A accuracy, on the protein in solution as well as in crystal. After photo-reduction, the iron-proximal histidine bond is shortened by 0.15 A, a reinforcement that should destabilize the iron in-plane position favoring water dissociation. Moreover, we are able to get the distance of the water molecule even after dissociation from the iron, with a 0.16-A statistical error.
KW - Ligand dynamics
KW - Myoglobin
KW - XANES
KW - Ligand dynamics
KW - Myoglobin
KW - XANES
UR - http://hdl.handle.net/10807/6827
M3 - Article
SN - 0006-3495
SP - 448
EP - 454
JO - Biophysical Journal
JF - Biophysical Journal
ER -