Quantitative analysis of X-ray Absorption Near Edge Structure data by a full multiple scattering procedure: The Fe-CO geometry in photolised carbonmonoxy-myoglobin single crystal

We report the first quantitative analysis of the Fe K-edge polarized x-ray absorption near edge structure of the iron protein carbonmonoxy-myoglobin (MbCO) single crystal and of its cryogenic photoproduct Mb*CO. The CO-Fe-heme local structure has been determined using a novel fitting procedure based on the full multiple scattering approach. The extracted local structure of Mb*CO includes a Fe-CO distance of (3.08 ± 0.07) Å, with a tilting angle between the heme normal and the Fe-C vector of (37 ± 7) degrees, and a bending angle between the Fe-C vector and the C-O bond of (31 ± 5)degrees.