2 I. INTRODUCTION II. PHOTOSYSTEM 0: THE MECHANISM 1. Fluctuating Light 2. Formation of Metastable Dipoles (a) Light-induced RC Dipoles and their Metastability (b) Distance Traversed within the RC by the Excited or Separated Electron (c) Number of Separated Electrons per RC (d) Contrast 3. The Photosynthetic Dipole Potential (a) The Dipole Potential (b) Surface Area per RC (c) Relative Dielectr...

The effect of linolenic acid on photosynthetic electron transport reactions in chloroplasts has been localized at a site on the donor side of photosystem I and at two functionally distinct sites in photosystem II.In photosystem I, an increase in the electron transport rate occurs in the presence of 10 to 100 micromolar linolenic acid, followed by a decline in rate from 100 to 200 micromolar lin...

Thylakoid membranes of the cryptophyte Chroomonas sp. strain LT were solubilized with dodecyl-beta-maltoside and subjected to sucrose density gradient centrifugation. The four pigment protein complexes obtained were subsequently characterized by absorption and fluorescence spectroscopy, SDS-PAGE, and Western immunoblotting using antisera against the chlorophyll a/c-binding proteins of the marin...

L-Ascorbate (Asc) plays important roles in plant development, hormone signaling, the cell cycle and cellular redox system, etc. The higher content of Asc in plant chloroplasts indicates its important role in the photosystem. The objective of this study was to study the roles of Asc in tall fescue leaves against heat stress. After a heat stress treatment, we observed a lower value of the maximum...

Environmental stresses lower the efficiency of photosynthesis and sometimes cause irreversible damage to plant functions. When spinach thylakoids and Photosystem II membranes were illuminated with excessive visible light (100-1,000 µmol photons m(-1) s(-1)) for 10 min at either 20°C or 30°C, the optimum quantum yield of Photosystem II decreased as the light intensity and temperature increased. ...

The activity of Photosystelil II reaction centers increases in the presence of dichlorobenzoquinone (DCBQ) compared to ferricyanide or dimethylbenzoquinone (DMBQ). We demonstrate that enhanced yields from Photosystem II in the presence of DCBQ depend on flash length (temporal distribution). A broad flash with extended decay enhances oxygen yields while a narrow flash without extended decay (300...

A comparison of the quantum yield spectra of the oxygenic (H(2)O as the electron donor) with the anoxygenic (H(2)S as the electron donor) photosynthesis of the cyanobacterium, Oscillatoria limnetica reveals that anoxygenic photosynthesis is driven by photosystem I only. The highest quantum yields of the latter (maximum; 0.059 CO(2) molecules/quantum of absorbed light) were obtained with wavelen...

The ability of photosystem (PS) II to catalyze the light-driven oxidation of water comes along with its vulnerability to oxidative damage, in particular of the D1 core subunit. Photodamaged PSII undergoes repair in a multi-step process involving (i) reversible phosphorylation of PSII core subunits; (ii) monomerization and lateral migration of the PSII core from grana to stroma thylakoids; (iii)...

Climate Change Cluster (C3), University of Technology Sydney, Ultimo, NSW, Australia, Division of Plant Sciences, Research School of Biology, Australian National University, Acton, ACT, Australia, 3 Biological Research Centre, Institute of Plant Biology, Hungarian Academy of Sciences, Szeged, Hungary, Centre for Sustainable Ecosystem Solutions, School of Biological Sciences, University of Wollo...