Electron paramagnetic resonance spectroscopy of Cu2+ in hen egg-white lysozyme

We have obtained the electron paramagnetic resonance spectrum of Cu2+bound in a tetragonal single crystal of hen egg-white lysozyme. A part of this spectrum has been shown to originate from Cu2+ions bound at the site designated as B by Teichberg et al. [Teichberg, V. I., Sharon, N., Moult, J., Smilansky, A. & Yonath, A. (1974) J. Mol. Biol. 87, 357-368]. The values of the spin hamiltonian parameters that describe this part of the spectrum are reported. The implications of these values with respect to the chemical nature and configuration of ligands are discussed. The other features of the spectrum are also described.