A Magnetic Susceptibility Study of Hemerythrin Using an Ultrasensitive Magnetometer

James W. Dawson1, Harry B. Gray1, H. Eckhardt Hoenig2, George R. Rossman1, Jeffrey M.  Schredder1, Run-Han Wang2

  1Arthur Amos Noyes Laboratory of Chemical Physics
 California Institute of Technology, Pasadena, CA

2The Alfred P. Sloan Laboratory of mathematics and Physics
California Institute of Technology, Pasadena, CA


The magnetic susceptibilities of oxy- and metaquohemerythrin in the range 3-200 K have been determined using an ultrasensitive superconducting quantum magnetometer, and for the first time their antiferromagnetic components have been conclusively resolved. The exchange coupling constants, J, between the two high-spin iron(III) atoms in each subunit are -77 and -134 cm-1, respectively. The electronic spectra of these two proteins in deuterium oxide have been measured from 800 to 1200 nm but no additional bands were obtained. After comparison to magnetic and spectroscopic data obtained previously for ferric dimer model complexes, it is concluded that the two iron(III) atoms in subunits of both oxy- and metaquohemerythrin are oxo bridged.


last updated: 28-Jul-2023