Synchrotron X-ray-Induced Photoreduction of Ferric Myoglobin Nitrite Crystals Gives the Ferrous Derivative with Retention of the O-Bonded Nitrite Ligand

• DOI: 10.1021/bi100801g
• Publication Date: 2010-06-22T16:02:19Z
• Authors: Jun Yi; Allen M. Orville; John M. Skinner; Michael J. Skinner; George B. Richter...
• Keywords: 0301 basic medicine; 03 medical and health sciences; Protein Conformation; Iron; Crystallography, X-Ray; Ligands; Metmyoglobin; Nitrites; Synchrotrons

Exposure of a single crystal of the nitrite adduct of ferric myoglobin (Mb) at 100 K to high-intensity synchrotron X-ray radiation resulted in changes in the UV-vis spectrum that can be attributed to reduction of the ferric compound to the ferrous derivative. We employed correlated single-crystal spectroscopy with crystallography to further characterize this photoproduct. The 1.55 A resolution crystal structure of the photoproduct reveals retention of the O-binding mode for binding of nitrite to the iron center. The data are consistent with cryogenic generation and trapping, at 100 K, of a ferrous d(6) Mb(II)(ONO)* complex by photoreduction of the ferric precursor crystals using high-intensity X-ray radiation.