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Updated: Jun 2, 2026
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Submillisecond Conformational Changes in Proteins Resolved by Photothermal Beam Deflection
Published on: February 18, 2014
Listening to PS II: enthalpy, entropy, and volume changes
Harvey J M Hou1, David Mauzerall
1Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA. hhou@umassd.edu
Summary
Understanding the thermodynamics of Photosystem II (PS II) electron transfer and oxygen evolution is crucial. This review summarizes thermodynamic parameters and highlights their importance for elucidating PS II mechanisms.
Area of Science:
- Photosynthesis research
- Bioenergetics
- Plant physiology
Background:
- Photosystem II (PS II) in thylakoid membranes drives water splitting using sunlight.
- While PS II structure and electron transfer rates are well-studied, its thermodynamic properties remain less understood.
- Thermodynamic parameters offer critical insights into the mechanisms of PS II function.
Purpose of the Study:
- To review and evaluate thermodynamic parameters of PS II photochemistry.
- To highlight the significance of enthalpic and entropic contributions to PS II function.
- To discuss future directions in studying PS II thermodynamics.
Main Methods:
- Photoacoustics and other laser-based techniques for measuring thermodynamic parameters.
- Analysis of quantum yield, enthalpy, entropy, and volume changes.
- Evaluation of light-driven volume changes (electrostriction) as a measure of PS II activity.
Main Results:
- Thermodynamic parameters like enthalpy and entropy changes provide critical information on PS II mechanisms.
- Light-induced volume changes are directly linked to PS II photoreactions.
- Photoacoustics enables direct measurement of reaction enthalpy changes.
Conclusions:
- Dissecting free energy into enthalpic and entropic components is key to understanding PS II function.
- Thermodynamic measurements offer novel insights into electron transfer and oxygen evolution.
- Further research into PS II thermodynamics is essential for a complete understanding.
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