Electron nuclear double resonance spectroscopy of a hen egg-white lysozyme--Cu2+ complex in tetragonal single crystals.

We have used the electron paramagnetic resonance of Cu2+ bound in a tetragonal single crystal of hen egg-white lysozyme to obtain the electron nuclear double resonance spectra of protons in the vicinity of the Cu2+ 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 hyperfine interaction parameters and the coordinates of eight protons are reported. The configuration of the H2O molecules coordinated to the Cu2+ and their relationships to the protein molecule structure are discussed.