THE ACTIVE-CENTER OF SUPEROXIDE-DISMUTASE FROM PROPIONIBACTERIUM-SHERMANII

A self-consistent description of the EPR spectra and of the Mossbauer spectra of the natural superoxide dismutase from Propionibacterium she rmanii with ferric iron as an active centre is presented. The spectra were measured at pH 6.5, 7.8 and 9.4. The theoretical approach is base d on the use of the complete crystal field Hamiltonian for the high-sp in ferric complexes with due regard for the terms of the fourth power of the electronic spin. It is shown that a SOD molecule can exist in t wo conformations. The low-pH conformation has predominantly trigonal s ymmetry, while the high-pH conformation has the symmetry close to the ''extreme rhombic''. This interpretation is in full agreement with EXA FS structural data.