title: Location of the High-Affinity Mn(2+) Site in Photosystem II Detected by PELDOR.
abstract: The location of the high-affinity Mn(2+) site in apo-photosystem (PS) II was investigated by pulsed EPR. The electron-electron magnetic dipole interaction of 1.7 MHz between the YD(•) radical and Mn(2+) ion was observed using the pulsed electron-electron double resonance (PELDOR) technique, and the Mn(2+) ion was bound to one apo-PS II in the absence and presence of Ca(2+). PELDOR signals were calculated using the previously determined spin distribution on the YD(•) radical and its known position in the crystal structure, assuming that the specific Mn(2+) site was located in the oxygen evolving complex. The results show that the high-affinity Mn(2+) site is located at the position denoted by Mn4(A) in the native crystal structure. The Mn(2+) is coordinated with axial ligands Asp170 and Glu333 in the D1 polypeptide.
authors.affiliation: Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8602, Japan.
authors.forename: Mizue
authors.initials: M
authors.lastname: Asada
authors.affiliation: Division of Material Science (Physics), Graduate School of Science, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8602, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Mino