The pulsed electron-electron double resonance and "2 + 1" electron spin echo study of the oriented oxygen-evolving and Mn-depleted preparations of photosystem II

Abstract

A "2 + 1" electron spin echo method has been applied to measure the angular orientation of the radius-vector RDZ joining the redox-active tyrosine residues YD and YZ in membrance-oriented Mn-depleted preparation of photosystem II. The angle between RDZ and the normal to the photosystem II membrane was determined to be 100° ± 2°, where the angle of 0° corresponds to the direction from YD towards the stromal side of the membrane, along the membrane normal. A pulsed electron-electron double resonance method has been used to obtain similar information for YD and Mn cluster in oriented sample of oxygen-evolving photosystem II. The angle between the radius-vector ffom YD to the Mn cluster, RDMn, and the membrane normal was found to be 110°±2°. © 1998 American Institute of Physics.