THE DIFFERENCE BETWEEN ADP-BERYLLIUM FLUORIDE AND ADP-ALUMINUM FLUORIDE COMPLEXES OF THE SPIN-LABELED MYOSIN SUBFRAGMENT-1

Electron paramagnetic resonance (EPR) spectroscopy was used for invest igation of the structure of spin-labeled myosin subfragment 1 (S1) con taining ADP and phosphate analogues, such as orthovanadate, aluminium fluoride (AIF(4)), and beryllium fluoride (BeFx). It has been shown th at the local conformational changes in the region of Cys-707, induced by formation of the S1-ADP-BeFx complex, differ from those of S1 conta ining ADP-AIF(4) or other phosphate analogues but are similar to the c hanges which occur in the presence of ADP or ATP gamma S, It is sugges ted that S1-ADP-AIF(4) and S1-ADP-BeFx complexes represent structural analogues of different transition states of the ATPase cycle, namely t he intermediate states S1*-ADP-P-1 and S1*-ATP, respectively.