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Start Over Subject thermal deactivation

1. Interactions between photosynthetic pigments in organisms and in model systems

Creator:
Frąckowiak, D. and Smyk, B.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
carotenoids, chlorophylls, delayed luminescence, excitation energy migration, models, photoacoustic spectroscopy, photosystem 2 reaction centres, polarized radiation, and thermal deactivation
Language:
Multiple languages
Description:
The review summarizes results concerning photosynthetic systems with chlorophylls and carotenoids obtained by means of spectral methods such as polarized radiation, photoacoustic spectroscopy, delayed luminescence, thermal deactivation, and leading to construction of model systems. and D. Frąckowiak, B. Smyk.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Interactions of chlorophyll and polypeptide mixture with bacterial reaction centres

Creator:
Enomoto, H., Takeda, S., Nakamura, C., Miyake , J., Ptak, A., Dudkowiak, A., and Frąckowiak, D.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
absorption spectra, fluorescence spectra, photoacoustic spectra, Rhodobacter sphaeroides, and thermal deactivation
Language:
Multiple languages
Description:
In aqueous solutions of chlorophyll (Chl) a with synthesized polypeptides, at high ratios of Chl to polypeptides (about 75-150 µM to 500 µM) clusters of polypeptides and pigment molecules were formed. The main absorption maxima of more than one formed cluster were located at about 500 nm (Soret band) and in the region of 720-806 nm (red band). The formation of these clusters was fairly slow (some hours) at room temperature and even slower at 4 °C. The rate of cluster formation increased with the increase in Chl concentration. The addition of the even low amount of reaction centres (RCs), separated from the purple bacteria Rhodobacter sphaeroides, to the sample of Chl with polypeptides caused a very strong decrease in the efficiency of cluster formation, and a change in concentration ratios of various pigment-polypeptide aggregates. It was probably a competition between the interaction of Chl with polypeptides and with the RCs. The yield of thermal deactivation of the clusters was high, much higher than that for the RCs alone and it was different for various types of cluster. The clusters absorbing at 725-750 nm were fluorescent with maximum of emission at about 770 nm, whereas clusters absorbing at about 800 nm were nonfluorescent. and H. Enomoto ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. The polarized photoacoustic spectra of Rhodobacter sphaeroides cells embedded in polymer and strongly irradiated by polarized radiation

Creator:
Goc, J. and Klecha, K.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
absorption, bacteriochlorophyll, carotenoids, chromophore, light-harvesting complex, purple photosynthetic bacteria, and thermal deactivation
Language:
Multiple languages
Description:
The cells of purple photosynthetic bacterium Rhodobacter sphaeroides embedded in stretched polymer films were irradiated by strong polarized "white light" with an electric vector parallel to the direction of film stretching. The polarized absorption and photoacoustic spectra before and after strong irradiation were measured. Measurements of absorbance showed no confident anisotropy before and after strong irradiation. In contradiction, the photoacoustic method showed after strong irradiation some changes in anisotropy of thermal deactivation due to the perturbation of the fate of excitations. The increase in yield of thermal deactivation, higher in a region of light-harvesting complex 2, can be explained by the irreversible changes in the conformation of the complexes due to strong irradiance reported up to now predominantly for thylakoid antenna complexes. and J. Goc, K. Klecha.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public