EXAFS and Near Edge Structure IV

J. Phys. Colloques 47 (1986) C8-1147-C8-1150
DOI: 10.1051/jphyscol:19868223

HIGH-RESOLUTION XANES STUDY OF THERMAL SPIN EQUILIBRIUM IN MYOGLOBIN

H. OYANAGI¹, E.W. SVASTITS², T. IIZUKA³, T. MATSUSHITA⁴, S. SAIGO⁵, R. MAKINO³ et Y. ISHIMURA<sup>3

1</sup>  Electrotechnical Laboratory, Sakuramura, Niiharigun, Ibaraki 305, Japan
²  Department of Chemistry, University of South Carolina, Columbia, SC 29208, U.S.A.
³  Department of Biochemistry, School of Medicine, Keio University, Shinanomachi, Shinjuku, Tokyo 160, Japan
⁴  National Laboratory for High Energy Physics, Ohomachi, Tsukubagun, Ibaraki 305, Japan
⁵  Department of Physics, Jichi Medical School, Yakushiji, Minamikawachi, Tochigi 329-04, Japan

Abstract
The local structure of heme-iron of alkaline met-myoglobin during the thermal spin equilibrium between high and low spin states has been studied by a high resolution XANES. The spin-state sensitive near edge features have been found in the near threshold region, which are related to the distorted ligand field. The spin-state sensitive near-edge structures were also found for other myoglobin derivatives. From a systematic high resolution XANES study on MbCO, MbCN, and oxy-Mb, near-edge features which are sensitive to the angle between the diatomic ligand molecule and heme normal were found. These characteristic features can provide the elaborate local structure of heme-iron such as the displacement of iron atom from the heme plane or the bond angle of ligand molecule.