Location of two Mn2+ affinity sites in photosystem II detected by pulsed electron–electron double resonance

2021 ◽  
Author(s):  
Hiroyuki Mino ◽  
Mizue Asada
Keyword(s):  
Photosystem Ii ◽  
Double Resonance

scholarly journals Simulations of the 1 H electron spin echo–electron nuclear double resonance and 2 H electron spin echo envelope modulation spectra of exchangeable hydrogen nuclei coupled to the S 2 –state photosystem II manganese cluster

2002 ◽  
Vol 357 (1426) ◽  
pp. 1359-1366 ◽  
Author(s):  
Constantino P. Aznar ◽  
R. David Britt
Keyword(s):  
Photosystem Ii ◽  
Electron Spin ◽  
Spin Echo ◽  
Double Resonance ◽  
Electron Spin Echo ◽  
Oxygen Evolving Complex ◽  
Electron Nuclear Double Resonance ◽  
Paramagnetic Resonance ◽  
Pulsed Epr ◽  
Envelope Modulation

The pulsed EPR methods of electron spin echo envelope modulation (ESEEM) and electron spin echo–electron nuclear double resonance (ESE–ENDOR) are used to investigate the proximity of exchangeable hydrogens around the paramagnetic S 2 –state Mn cluster of the photosystem II oxygen–evolving complex. Although ESEEM and ESE–ENDOR are both pulsed electron paramagnetic resonance techniques, the specific mechanisms by which nuclear spin transitions are observed are quite different. We are able to generate good simulations of both 1 H ESE–ENDOR and 2 H ESEEM signatures of exchangeable hydrogens at the S 2 –state cluster. The convergence of simulation parameters for both methods provides a high degree of confidence in the simulations. Several exchangeable protons–deuterons with strong dipolar couplings are observed. In the simulations, two of the close (≈2.5 Å) hydrogen nuclei exhibit strong isotropic couplings and are therefore most probably associated with direct substrate ligation to paramagnetic Mn. Another two of the close (≈2.7 Å) hydrogen nuclei show no isotropic couplings and are therefore most probably not contained in Mn ligands. We suggest that these proximal hydrogens may be associated with a Ca 2+ –bound substrate, as indicated in recent mechanistic proposals for O 2 formation.

55Mn-ENDOR of the S2-state multiline signal of Photosystem II from Thermosynechococcus elongatus

2008 ◽  
Vol 36 (5) ◽  
pp. 1001-1004 ◽  
Author(s):  
Susanne Pudollek ◽  
Friedhelm Lendzian ◽  
Robert Bittl
Keyword(s):  
Photosystem Ii ◽  
Double Resonance ◽  
Oxygen Evolving Complex ◽  
Electron Nuclear Double Resonance ◽  
Pulse Epr ◽  
S2 State ◽  
Oxygen Evolving

Pulse EPR and 55Mn-ENDOR (electron nuclear double resonance) experiments at 34 GHz (Q-band) were performed on the S2 state of the OEC (oxygen-evolving complex) in PSII (Photosystem II) from Thermosynechococcus elongatus. The ENDOR spectra are discussed with respect to earlier data obtained from X- (9 GHz) and Q-band experiments on PSII preparations from spinach with and without the addition of methanol.

scholarly journals Location of the extrinsic subunit PsbP in photosystem II studied by pulsed electron-electron double resonance

2018 ◽  
Vol 1859 (5) ◽  
pp. 394-399 ◽  
Author(s):  
Mizue Asada ◽  
Taishi Nishimura ◽  
Kentaro Ifuku ◽  
Hiroyuki Mino
Keyword(s):  
Photosystem Ii ◽  
Double Resonance
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