ISSN:
1573-5079
Keywords:
hydrostatic pressure
;
Photosystem II
;
pigment exchange
;
reaction center
;
spectral shift
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Absorption spectra of the D1-D2-cytochrom b559 complex at 4°C were investigated at pressures up to 300 MPa. Pressure effects were mostly reversible and independent of the detergent used (CHAPS or dodecyl-β-D-maltoside). Red-shifts were observed under pressure for the chlorophyll Qy- and the β-carotene S0 → S2 bands. The relatively small Qy-shift of approximately 0.15 cm-1/MPa is an indication for the absence of strongly coupled chlorophyll dimers within the reaction center and supports earlier reports from low-temperature measurements (Chang HC, Jankowiak R, Reddy NRS and Small GJ (1995) Chem Phys 197: 307–321). The carotene red-shift (seen in CHAPS) is much larger (0.5 – 0.6 cm-1/MPa) and within the range observed for excitonically coupled chlorophylls. However, since carotenes are more sensitive to changes of refractive index, we do not consider this evidence for excitonically coupled carotenes. Varying the pH and the detergent induced only small effects. Pigment exchange using high pressure instead of elevated temperature was not possible under the conditions tested.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1005876310854
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