Transcriptional regulation of chloroplast genes is demonstrated by Quantitative Polymerase Chain Reaction (qPCR). These genes encode apoproteins of the reaction centres of photosystem I and photosystem II. Their transcription is regulated by changes in wavelength of light selectively absorbed by photosystem I and photosystem II, and therefore by the redox state of an electron carrier located be...

Even though light is the ultimate substrate for photosynthetic energy conversion, it can also harm plants. This toxicity is targeted to the water-splitting photosystem II and leads to damage and degradation of the reaction centre D1-polypeptide. The degradation of this very important protein appears to be a direct consequence of photosystem II chemistry involving highly oxidizing radicals and t...

The dynamics of charge separation in the photosystem II reaction center (PSII-RC) in the presence of intramolecular vibrations with their frequency matching the energy gap between the exciton state acting as the primary electron donor and the first charge-transfer (CT) state are investigated. A reduced PSII-RC 4-state model explicitly including a CT state is analyzed within Redfield relaxation ...

We report a structural characterization by electron microscopy and image analysis of a supramolecular complex consisting of seven trimeric light-harvesting complex II proteins. The complex was readily observed in partially-solubilized Tris-washed photosystem II membranes from spinach but was also found to occur, with a low frequency, in oxygen-evolving photosystem II membranes. The structure re...

The photosynthetic activity of marine phytoplankton from five algal classes (Phaeodactylum tricornutum, Skeletonema costatum, Thalassiosira oceanica, Thalassiosira weissflogii, Dunaliella tertiolecta, Mantoniella squamata, Emiliania huxleyi, Pavlova lutheri and Heterosigma akashiwo) was investigated under identical growth conditions to determine interspecies differences. Primary photochemistry ...

In a preceding paper [ 1 ] we presented experimental results, which led to the identification of four protolytic reaction sites in the functional membrane of photosynthesis: two sites of proton uptake at the outer side of the membrane, in agreement with prior studies [2] , and two sites of proton release into the inner phase. One of these sites had to be attributed to the reduction of the termi...

Two D2 mutants were created with a site-directed mutation near the presumable binding site of Qa. In one of the mutants, in which Trp-253, the aromatic residue potentially involved in facilitating electron transport from pheophytin to QA and/or in binding of QA, had been replaced by Leu, PS II was undetectable in thylakoids. This mutant is an obligate photoheterotroph. In another mutant the Gly...

A method is reported for the isolation of a highly resolved oxygen-evolving photosystem II reaction center preparation. This preparation can be separated from the more complex photosystem II membranes isolated by the procedure of Berthold et al. [(1981) FEBS Lett. 134, 231-2341 by use of octylglucopyranoside at elevated ionic strengths; the oxygen-evolving material can be collected by centrifug...

Photoinhibition was studied in osmotically broken chloroplasts isolated from spinach leaves (Spinacia oleracea L.). Both whole chain electron transport (measured as ferricyanide-dependent O(2) evolution in the presence of NH(4)Cl) and photosystem II activity (measured as O(2) evolution in the presence of either silicomolybdate plus 3-(3,4-diphenyl)-1,1 dimethylurea or parabenzoquinone) showed s...