May 3, 2011

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

Journal of Photochemistry and Photobiology. B, Biology
Harvey J M Hou, D Mauzerall


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...Continue Reading

  • References32
  • Citations4


Mentioned in this Paper

Spinach preparation
Photosynthetic Reaction Centers
Thylakoid Membrane
Complex (molecular entity)
Polydactyly, Preaxial II (Disorder)

Trending Feeds


Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Synthetic Genetic Array Analysis

Synthetic genetic arrays allow the systematic examination of genetic interactions. Here is the latest research focusing on synthetic genetic arrays and their analyses.

Position Effect Variegation

Position Effect Variagation occurs when a gene is inactivated due to its positioning near heterochromatic regions within a chromosome. Discover the latest research on Position Effect Variagation here.

Head And Neck Squamous Cell Carcinoma

Squamous cell carcinomas account for >90% of all tumors in the head and neck region. Head and neck squamous cell carcinoma incidence has increased dramatically recently with little improvement in patient outcomes. Here is the latest research on this aggressive malignancy.

Signaling in Adult Neurogenesis

Neural stem cells play a critical role in the production of neuronal cells in neurogenesis is of great importance. Of interest is the role signalling mechanisms in adult neurogenesis. Discover the latest research on signalling in adult neurogenesis.

Psychiatric Chronotherapy

Psychiatric Chronotherapy considers the circadian rhythm as a major factor for optimizing therapeutic efficacy of psychiatric interventions. Discover the latest research on Psychiatric Chronotherapy here.

Epigenetic Memory

Epigenetic memory refers to the heritable genetic changes that are not explained by the DNA sequence. Find the latest research on epigenetic memory here.

Bone Marrow Neoplasms

Bone Marrow Neoplasms are cancers that occur in the bone marrow. Discover the latest research on Bone Marrow Neoplasms here.