[Structural characteristics of paramagnetic analogs of enzyme-substrate complexes of phosphorylation coupling factors].

Mn2+-ion is linked to isolated chloroplast coupling factor CF-1 via the ATP bridge in the catalytically competent ternary complex as deduced from water proton relaxation rate measurements. Two essential SH-groups in CF-1 protein were modified with nitroxyl mercuric derivative as spin label. The substrate complex Ca2+-ATP is shown to induce the structural transition near the active site to the state with a stronger immobilized spin label. The distances between the paramagnetic metal ions and nitroxyl bound to the protein SH-group were evaluated as being in the range of 5-8,5 A for Cu2+ and 14-22 A for Mn2+.