Redox-induced structural dynamics of Fe-heme-ligand in myoglobin by X-ray Absorption Spectroscopy

Alessandro Arcovito, Stefano Della Longa, Maurizio Benfatto, Agostina Congiu Castellano, Marco Girasole, Jean Louis Hazemann, Antonella Lo Bosco

Risultato della ricerca: Contributo in rivistaArticolo in rivistapeer review

39 Citazioni (Scopus)

Abstract

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.
Lingua originaleEnglish
pagine (da-a)448-454
Numero di pagine7
RivistaBiophysical Journal
Stato di pubblicazionePubblicato - 2003

Keywords

  • Ligand dynamics
  • Myoglobin
  • XANES

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