An X-ray diffraction and X-ray absorption spectroscopy joint study of neuroglobin

• Published in: Archives of biochemistry and biophysics Vol. 475; no. 1; pp. 7 - 13
• Main Authors: Arcovito, Alessandro, Moschetti, Tommaso, D’Angelo, Paola, Mancini, Giordano, Vallone, Beatrice, Brunori, Maurizio, Della Longa, Stefano
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.07.2008
• Subjects: Animals; Carbon Monoxide - chemistry; Cloning, Molecular; Escherichia coli - genetics; EXAFS; Globins - chemistry; Globins - genetics; Globins - metabolism; Heme - chemistry; Hemeproteins; Histidine - chemistry; Iron - chemistry; Mice; Nerve Tissue Proteins - chemistry; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Neuroprotection; Oxidation-Reduction; Protein Binding; Recombinant Proteins - chemistry; Recombinant Proteins - isolation & purification; Recombinant Proteins - metabolism; Spectrum Analysis - methods; Synchrotron radiation; X-Ray Diffraction - methods; X-Rays; XANES; Neuroprotection; Hemeproteins; XANES; EXAFS; Synchrotron radiation
• ISSN: 0003-9861; 1096-0384; 1096-0384
• DOI: 10.1016/j.abb.2008.03.026

Neuroglobin (Ngb) is a member of the globin family expressed in the vertebrate brain, involved in neuroprotection. A combined approach of X-ray diffraction (XRD) on single crystal and X-ray absorption spectroscopy (XAS) in solution, allows to determine the oxidation state and the structure of the Fe–heme both in the bis-histidine and the CO-bound (NgbCO) states. The overall data demonstrate that under X-ray the iron is photoreduced fairly rapidly, and that the previously reported X-ray structure of ferric Ngb [B. Vallone, K. Nienhaus, M. Brunori, G.U. Nienhaus, Proteins 56 (2004) 85–92] very likely refers to a photoreduced species indistinguishable from the dithionite reduced protein. Results from the XAS analysis of NgbCO in solution are in good agreement with XRD data on the crystal. However prolonged X-ray exposure at 15 K determines CO release. This preliminary result paves the way to experiments aimed at the characterization of pentacoordinate ferrous Ngb, the only species competent in binding external ligands such as O 2, CO or NO.