Quantum Requirement for Oxygen Evolution in Photosystem II: New Experimental Data and Theoretical Solutions
We used a X-Ray crystallography model of the photosystem II (PSII) to perform for the first time a structure-function demonstration showing that the minimal quantum requirement for oxygen evolution, QRO2, in the PSII reaction center is eight photons/oxygen molecule evolved. The results indicate that the minimal QRO2 = 8 is not dependent on the partaking of the calculated quantum requirement between PSII and photosystem I as was often reported. The differences between the minimal QRO2 = 8 calculated in this work and the experimental QRO2's > 8 observed in various plant and algae materials (in particular QRO2 = 12.5 in isolated PSII particles) are explained by the participation of the chlorophylls PD2 or ChlD2 and the tyrosine D (in the D2 protein) in energy and electron transfer in the PSII reaction center.
KeywordsD2 protein electron transfer oxygen evolution Photosystem II quantum requirement
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