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

Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, Oklahoma 73019, USA.
Biochemistry (Impact Factor: 3.01). 07/2010; 49(29):5969-71. DOI: 10.1021/bi100801g
Source: PubMed

ABSTRACT 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.

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