Electron-nuclear-double-resonance studies of spinach plastocyanin

Abstract
Electron-nuclear-double-resonance (ENDOR) studies of spinach plastocyanin revealed that 14N-hyperfine couplings from its 2 co-ordinated imidazole groups are characteristically small in anisotropy and relatively high in ENDOR frequencies and that the 2 imidazole groups are magnetically equivalent. The relatively strong Cu-imidazole co-ordinate bonds of plastocyanin are a result of the coexistence of a strong Cu-thiol co-ordinate bond.