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Listening to PS II: Enthalpy, entropy, and volume changes

Paper ID Volume ID Publish Year Pages File Format Full-Text
29643 44425 2011 9 PDF Available
Title
Listening to PS II: Enthalpy, entropy, and volume changes
Abstract

Photosystem II, located in the thylakoid membranes of green plants, algae, and cyanobacteria, uses sunlight to split water into protons, electrons, and a dioxygen molecule. The mechanism of its electron transfers and oxygen evolution including the structure of the protein and rates of the S-state cycle has been extensively investigated. Substantial progress has been made; however, the thermodynamics of PS II electron transfer and of the oxygen cycle are poorly understood. Recent progress in thermodynamic measurements in photosynthesis provides novel insights on the enthalpic and entropic contribution to electron transfer in proteins. In this review the thermodynamic parameters including quantum yield, enthalpy, entropy, and volume changes of PS II photochemistry determined by photoacoustics and other laser techniques are summarized and evaluated. Light-driven volume changes via electrostriction are directly related to the photoreaction in PS II and thus can be a useful measurement of PS II activity and function. The enthalpy changes of the reactions observed can be directly measured by photoacoustics. The apparent reaction entropy can also be estimated when the free energy is known. Dissecting the free energy of a photoreaction into enthalpic and entropic components provides critical information about mechanisms of PS II function. Potential limitations and future direction of the study of the thermodynamics of PS II electron transfer and oxygen evolution are presented.

Graphical abstractRecent thermodynamic measurements in photosystem II provide novel insights in the electron transfer mechanisms. In this review the thermodynamic parameters including quantum yield, enthalpy, entropy, and volume changes of photosystem II photochemistry determined by photoacoustics and other laser techniques are summarized and evaluated. Potential limitations and future direction in this area are presented.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Thermodynamics of electron transfers in PS II are summarized and evaluated. ► The parameters include quantum yield, enthalpy, entropy, and volume changes. ► Photoacoustics uncovers the enthalpic and entropic contribution in PS II.

Keywords
Thermodynamics; PS II; Photoacoustics; Enthalpy; Entropy; Volume change
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Listening to PS II: Enthalpy, entropy, and volume changes
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 104, Issues 1–2, July–August 2011, Pages 357–365
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us