Oxygen-evolving Photosystem II core complexes: a new paradigm based on the spectral identification of the charge-separating state, the primary acceptor and assignment of low-temperature fluorescence

2005 ◽  
Vol 4 (9) ◽  
pp. 744 ◽  
Author(s):  
Elmars Krausz ◽  
Joseph L. Hughes ◽  
Paul Smith ◽  
Ron Pace ◽  
Sindra Peterson Årsköld
Keyword(s):  
Low Temperature ◽  
Photosystem Ii ◽  
New Paradigm ◽  
Spectral Identification ◽  
Primary Acceptor ◽  
Oxygen Evolving

Assignment of the low-temperature fluorescence in oxygen-evolving Photosystem II

2005 ◽  
Vol 84 (1-3) ◽  
pp. 193-199 ◽  
Author(s):  
Elmars Krausz ◽  
Joseph L. Hughes ◽  
Paul J. Smith ◽  
Ron J. Pace ◽  
Sindra Peterson Årsköld
Keyword(s):  
Low Temperature ◽  
Photosystem Ii ◽  
Oxygen Evolving

scholarly journals A relationship between the midpoint potential of the primary acceptor and low temperature photochemistry in photosystem II

FEBS Letters ◽  
1983 ◽  
Vol 154 (2) ◽  
pp. 328-334 ◽  
Author(s):  
A.W. Rutherford ◽  
P. Mathis
Keyword(s):  
Low Temperature ◽  
Photosystem Ii ◽  
Midpoint Potential ◽  
Primary Acceptor

The Native Reaction Centre of Photosystem II: A New Paradigm for P680

2004 ◽  
Vol 57 (12) ◽  
pp. 1179 ◽  
Author(s):  
Joseph L. Hughes ◽  
Barry J. Prince ◽  
Sindra Peterson Årsköld ◽  
Paul J. Smith ◽  
Ron J. Pace ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Charge Separation ◽  
Action Spectrum ◽  
Hole Burning ◽  
Spectral Hole Burning ◽  
Reaction Centre ◽  
New Paradigm ◽  
Temperature Spectra ◽  
Inner Light ◽  
Oxygen Evolving

Low-temperature spectra of fully active (oxygen-evolving) Photosystem II (PSII) cores prepared from spinach exhibit well developed structure. Spectra of isolated sub-fragments of PSII cores establish that the native reaction centre is better structured and red-shifted compared to the isolated reaction centre. Laser illumination of PSII cores leads to efficient and deep spectral hole-burning. Measurements of homogeneous hole-widths establish excited-state lifetimes in the 40–300 ps range. The high hole-burning efficiency is attributed to charge separation of P680 in native PSII that follows reaction-centre excitation via ‘slow transfer’ states in the inner light-harvesting assemblies CP43 and CP47. The ‘slow transfer’ state in CP47 and that in CP43 can be distinguished in the hole-burning action spectrum and high-resolution hole-burning spectra. An important observation is that 685–700 nm illumination gives rise to efficient P680 charge separation, as established by QA− formation. This leads to a new paradigm for P680. The charge-separating state has surprisingly weak absorption and extends to 700 nm.

Characterization of photosystem II with the atomic-force microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 1146-1147
Author(s):  
Kathleen M. Marr ◽  
Mary K. Lyon
Keyword(s):  
Photosystem Ii ◽  
Atomic Force Microscope ◽  
Three Dimensional ◽  
Biologically Active ◽  
Atomic Force ◽  
Freeze Etching ◽  
Image Averaging ◽  
Oxygen Evolving ◽  
Averaging Techniques

Photosystem II (PSII) is different from all other reaction centers in that it splits water to evolve oxygen and hydrogen ions. This unique ability to evolve oxygen is partly due to three oxygen evolving polypeptides (OEPs) associated with the PSII complex. Freeze etching on grana derived insideout membranes revealed that the OEPs contribute to the observed tetrameric nature of the PSIl particle; when the OEPs are removed, a distinct dimer emerges. Thus, the surface of the PSII complex changes dramatically upon removal of these polypeptides. The atomic force microscope (AFM) is ideal for examining surface topography. The instrument provides a topographical view of individual PSII complexes, giving relatively high resolution three-dimensional information without image averaging techniques. In addition, the use of a fluid cell allows a biologically active sample to be maintained under fully hydrated and physiologically buffered conditions. The OEPs associated with PSII may be sequentially removed, thereby changing the surface of the complex by one polypeptide at a time.

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