Distribution of conformational states as common source of g-and A-strain in the ESR spectra of proteins and glasses

2014 Additional experimental evidence on the structural and dynamical similarity between proteins and glasses is provided by the analysis conducted on the ESR spectra, at different temperatures, of some copper proteins and of some Cu++-doped glasses formed by water and a second component (NaOH, DMSO, alcohols). All the spectra taken at temperatures below ~ 210 K display a significant gand A-strain that consists in a progressive broadening and decrese in the intensity of the copper hyperfine lines as the order of mI increases (I = 3/2 is the Cu nuclear spin). These spectral features are taken into account by using a theoretical model which attributes the random distribution of the electric ligand fields around the copper ions to a distribution of the conformational substate energies both in the proteins and in the amorphous materials. J. Phys. France 51 (1990) 131-139 ler JANVIER 1990, Classification Physics Abstracts 76.30 61.40 87.15