Determination of iron-ligand bond lengths in horse heart met- and deoxymyoglobin using multiple-scattering XAFS analyses

Journal Article · Mon Nov 02 00:00:00 EST 1998 · Inorganic Chemistry

DOI:https://doi.org/10.1021/ic9714549· OSTI ID:316204

Rich, A M; Armstrong, R S; Ellis, P J; Freeman, H C; Lay, P A ^[1]

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1. Univ. of Sydney, New South Wales (Australia). School of Chemistry

XAFS data in the range 0 {le} k {le} 14.5 {angstrom}{sup {minus}1} have been obtained from frozen aqueous solutions (10 K) of horse heart myoglobin (Mb) in the Fe(III) (aqua-met) and Fe(II) (deoxy) forms. The structures of the Fe sites have been refined using both single-scattering (SS) and multiple-scattering (MS) analyses. The XAFS MS analyses yield more precise Fe-ligand bond lengths (estimated error 0.02--0.03 {angstrom}) than those determined crystallographically (estimated errors {ge} 0.1 {angstrom}). For met-Mb, the MS analysis results in an average Fe-N(pyrrole) distance of 2.05 {angstrom}, an Fe-N(imidazole) distance of 2.17 {angstrom}, and an Fe-O(aqua) distance of 2.08 {angstrom}. For deoxy-Mb, the MS analysis results in Fe-N(pyrrole) and Fe-N(imidazole) distances of 2.06 and 2.16 {angstrom}, respectively. The final XAFS R values are 18.8% and 17.8% for met- and deoxy-Mb, respectively. The robustness of the refinements was tested by varying the starting models, constraints, restraints, and k ranges.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• OSTI ID: 316204
• Journal Information: Inorganic Chemistry, Vol. 37, Issue 22; Other Information: PBD: 2 Nov 1998
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
BOND LENGTHS
IRON COMPOUNDS
MYOGLOBIN
HORSES
CRYSTAL STRUCTURE
X-RAY SPECTROSCOPY
ABSORPTION SPECTROSCOPY