chlorophyll-a has been researched along with phenylbenzoquinone* in 4 studies
4 other study(ies) available for chlorophyll-a and phenylbenzoquinone
| Article | Year |
|---|---|
The coupled photocycle of phenyl-p-benzoquinone and Light-Harvesting Complex II (LHCII) within the biohybrid system.
The combination of trimeric form of the light-harvesting complex II (LHCII Topics: Benzoquinones; Chlorophyll; Fluorescence; Graphite; Light-Harvesting Protein Complexes; Photosystem II Protein Complex | 2022 |
PSII as an in vivo molecular catalyst for the production of energy rich hydroquinones - A new approach in renewable energy.
One of the pertinent issues in the field of energy science today is the quest for an abundant source of hydrogen or hydrogen equivalents. In this study, phenyl-p-benzoquinone (pPBQ) has been used to generate a molecular store of hydrogen equivalents (phenyl-p-hydroquinone; pPBQH Topics: Benzoquinones; Biocatalysis; Chlorophyll; Chlorophyll A; Cyanobacteria; Hydrogen; Hydroquinones; Light; Oxidation-Reduction; Photolysis; Photosystem II Protein Complex; Renewable Energy; Water | 2018 |
Effects of noncovalently bound quinones on the ground and triplet states of zinc chlorins in solution and bound to de novo synthesized peptides.
The Qy absorption band of two chlorophyll derivatives, zinc chlorin e6 (ZnCe6) and zinc pheophorbide a (ZnPheida), in aqueous solution is bathochromically shifted on addition of quinones, e.g., 1,4-benzoquinone (BQ), with a corresponding shift of the fluorescence band. This is due to a complex formation of zinc chlorins induced by BQs and subsequent rearrangement. The time-resolved absorption spectra after laser pulse excitation show triplet quenching of the pigments by BQ and other quinones via electron transfer. The effects of electron transfer to noncovalently bound BQs were also studied with de novo synthesized peptides, into which ZnCe6 and ZnPheida were incorporated as model systems for the primary steps of photosynthetic reaction centers. Whereas the photophysical properties are similar to those of the unbound zinc chlorins, no BQ-mediated complex formation was observed. Topics: Benzoquinones; Chlorophyll; Chlorophyllides; Kinetics; Organometallic Compounds; Porphyrins; Protein Conformation; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Zinc | 2006 |
The S3 state of photosystem II: differences between the structure of the manganese complex in the S2 and S3 states determined by X-ray absorption spectroscopy.
O2-evolving photosystem II (PSII) membranes from spinach have been cryogenically stabilized in the S3 state of the oxygen-evolving complex. The cryogenic trapping of the S3 state was achieved using a double-turnover illumination of dark-adapted PSII preparations maintained at 240 K. A double turnover of PSII was accomplished using the high-potential acceptor, Q400, which is the high-spin iron of the iron-quinone acceptor complex. EPR spectroscopy was the principal tool establishing the S-state composition and defining the electron-transfer events associated with a double turnover of PSII. The inflection point energy of the Mn X-ray absorption K-edge of PSII preparations poised in the S3 state is the same as for those poised in the S2 state. This is surprising in light of the loss of the multiline EPR signal upon advancing to the S3 state. This indicates that the oxidative equivalent stored within the oxygen-evolving complex (OEC) during this transition resides on another intermediate donor which must be very close to the manganese complex. An analysis of the Mn extended X-ray absorption fine structure (EXAFS) of PSII preparations poised in the S2 and S3 states indicates that a small structural rearrangement occurs during this photoinduced transition. A detailed comparison of the Mn EXAFS of these two S states with the EXAFS of four multinuclear mu-oxo-bridged manganese compounds indicates that the photosynthetic manganese site most probably consists of a pair of binuclear di-mu-oxo-bridged manganese structures. However, we cannot rule out, on the basis of the EXAFS analysis alone, a complex containing a mononuclear center and a linear trinuclear complex. The subtle differences observed between the S states are best explained by an increase in the spread of Mn-Mn distances occurring during the S2----S3 state transition. This increased disorder in the manganese distances suggests the presence of two inequivalent di-mu-oxo-bridged binuclear structures in the S3 state. Topics: Benzoquinones; Chemical Phenomena; Chemistry, Physical; Chlorophyll; Cytochrome b Group; Electron Spin Resonance Spectroscopy; Electron Transport; Ferricyanides; Fourier Analysis; Light; Light-Harvesting Protein Complexes; Manganese; Photosynthetic Reaction Center Complex Proteins; Photosystem II Protein Complex; Plant Proteins; Plants; Quinones; Spectrum Analysis; X-Rays | 1990 |