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Title Redox active tyrosines in photosystem II: role in proton coupled electron transfer reactions
Publication Date
Date Accessioned
Degree PhD
Discipline/Department Chemistry and Biochemistry
Degree Level doctoral
University/Publisher Georgia Tech
Abstract Proton coupled electron transfer reactions often involve tyrosine residues, because when oxidized, the phenolic side chain deprotonates. Tyrosine Z (YZ) is responsible for extracting electrons in a stepwise fashion from the oxygen evolving-complex in order to build enough potential to oxidize water. This process requires that each step YZ must deprotonate and reprotonate in order to maintain the high midpoint potential that is necessary to oxidize the oxygen-evolving complex, which makes YZ highly involved in proton coupled electron transfer reactions. In this thesis YZ has been studied within oxygen-evolving photosystem II utilizing electron paramagnetic resonance spectroscopy to monitor the tyrosyl radical that is formed upon light excitation. Kinetic analysis of YZ has shed light on the factors that are important for PSII to carry out water oxidation at the oxygen-evolving complex. Most notably the strong hydrogen-bonding network and the midpoint potential of YZ have been shown to be integral aspects of the water splitting reactions of PSII. By studying YZ within oxygen-evolving PSII, conclusions are readily applied to the native system.
Subjects/Keywords Photosystem II; Proton coupled electron transfer reactions; Tyrosine Z; Tyrosine D; YZ; YD; Water oxidation; Photosynthesis; Power resources Research; Photosynthetic reaction centers
Contributors Bridgette A. Barry (Committee Chair); Adegboyega K. Oyelere (Committee Member); Facundo Fernandez (Committee Member); Ingeborg Schmidt-Krey (Committee Member); Mostafa El-Sayed (Committee Member)
Country of Publication us
Record ID handle:1853/47738
Repository gatech
Date Indexed 2020-05-13
Issued Date 2013-01-07 00:00:00
Note [degree] PhD; [advisor] Committee Chair: Bridgette A. Barry; Committee Member: Adegboyega K. Oyelere; Committee Member: Facundo Fernandez; Committee Member: Ingeborg Schmidt-Krey; Committee Member: Mostafa El-Sayed;

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…solvent isotope dependence of YZ• decay at 190 K, as assessed by the half-time for the overall reaction. (A) pL dependence in the S2 state. The black line shows data acquired in 1H2O and the red line shows data acquired in 2H2O. (B) pL…

…neutral radical. In the bottom panel, the reduction of YZ and calcium bound water and His190-D1 compete to donate a proton. In this paper, we are monitoring the reduction (bottom) reaction. .............. 61 Figure 3.9. Reaction diagram…

…Photosynthesis is among the most fundamental energy conversion process known.(5) Oxygenic photosynthetic processes convert light and CO2 into an estimated 4 to 17 x 1011 tons of reduced carbon each year, which is the equivalent to harnessing between 1 x…

…x28;4, 8) As long as fossil fuels remain the cheaper option, motivation will be lacking to pay for a cleaner form of energy. For these reasons, we should strive to understand photosynthetic processes in order to create processes that are cheaper and…

…this process occurs in the thylakoid membranes of all photosynthetic organisms to produce adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH).(9) The simplest apparatus is found within…

…prokaryotic cyanobacteria where the plasma membrane forms invaginations that contain the photosynthetic proteins (Figure 1.2B). Plants and algae utilize a more complex setup. The thylakoid membrane is stacked organelles within chloroplasts. The…

…stacked regions of thylakoid membranes are called the grana and the regions that connect the grana are termed the lamellae (Figure 1.2A). Plants accumulate different photosynthetic proteins in each of these areas of the thylakoid membrane…

…side of the complex. On the stromal side of the complex, within the membrane, two molecules of plastoquinone (PQ) are reduced to two 2 Figure 1.1. Cartoon depiction of a thylakoid membrane containing the photosynthetic proteins. From left…