Spin lattice relaxation studies on iron proteins
The fractal model relating protein structure and vibrational dynamics is reviewed and refined. The temperature dependence of electron spin-lattice relaxation stimulated by Raman phonon scattering is measured in low spin ferric proteins. The data are analysed to yield the spectral dimension, a parameter characterizing the protein vibrational dynamics. Protein X-ray coordinate s are used to approximate a static structural parameter, the fractal dimension. These parameters are related as scaling exponents using simple physical arguments and experimental results. Central issues addressed are the domain of length scales over which the tabulated fractal dimension is a valid scaling exponent and the frequency range of protein vibrations contributing to the measurement of the spectral dimension. Recent experimental findings are interpreted to relate these regimes. They reveal a transition in the spectral dimension from reflecting the protein structure above 6K, to that of the surrounding solvent below this temperature.
electron spin-lattice relaxation, low spin iron proteins, protein structure, vibrational dynamics, Raman phonon scattering
University of Illinois - Urbana-Champaign
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