Resonance Raman spectroscopy of carotenoids in Photosystem II core complexes

Abstract

Resonance Raman (RR) spectroscopy has been used to examine the configuration of the carotenoids bound to Synechocystis PCC 6803 Photosystem II (PS II) core complexes. The excitation wavelengths used (514.5, 488.0, 476.5 and 457.9 nm) span the absorption bands of all of the approximately 12-17 neutral carotenoids in the PS II core complex. The RR spectra of the two carotenoids associated with the D1-D2 polypeptides (Car507 and Car489) of the reaction center are extracted via light versus dark difference experiments measured at 20 K. The RR results are consistent with all-trans configurations for both Car507 and Car489 and indicate that majority of the other carotenoids in the PS II core complex must also be in the all-trans configuration. The configuration of beta-carotene is relevant to its proposed function as a molecular wire in the secondary electron-transfer reactions of PS II.

In vivo hyperspectral confocal fluorescence imaging to determine pigment localization and distribution in cyanobacterial cells

“…Although this component contributed only Ϸ0.1% of the total spectral variance, it was easily identified as an independent component because of its spectral dissimilarity and distinct spatial location. The resonance Raman band positions and relative intensities were in line with those reported for carotenoids in PS I and PS II (35,36) and those of pure ␤-carotene in solution (data not shown).…”

Rapid resonance Raman microspectroscopy to probe carbon dioxide fixation by single cells in microbial communities

“…Many biological molecules are RR-active compounds and carotenoids are typical analytes for RR spectroscopy (Krebs et al, 2003;Robert 2009). More importantly, nearly all photosynthetic microorganisms contain carotenoids, which are essential elements of lightharvesting complexes and singlet oxygen quenchers (Szalontai et al, 1994;Garcia-Asua et al, 1998;Tracewell et al, 2001Tracewell et al, , 2005.…”

Will Raman meet bacteria on Mars? An overview of the optimal Raman spectroscopic techniques for carotenoid biomarkers detection on mineral backgrounds

“…The physical size and power consumption of these laser systems, however, are currently too large for space application: further technical developments are expected to reduce the instrumental size and power consumption and planetary rovers equipped with such tuneable laser systems may be applied in the near future. Such systems would offer the possibility of carrying out more sensitive and more selective Raman measurements under resonant conditions (Tracewell et al, 2005; Bonifacio et al, 2008; Gaft & Nagli, 2008). This is needed because, for example, carotenoids are sensitive to their environment and that influences the resonance conditions (Britton, 1995; Hooijschuur et al, 2015).…”

“…Because RRS only works for specific compounds, it provides selectivity for that compound over any associated matrix. Examples of this approach include RRS of carotenoid pigments in photosystem II complexes (Tracewell et al, 2005) and haem groups inside a cellular matrix (Bonifacio et al, 2008). Although this technique is very useful for the detection of particular resonant biomarkers, extraterrestrial life does not necessarily contain chromophores similar to terrestrial molecules, therefore excitation using a tuneable laser source providing variable but controlled irradiance conditions would provide the best chance to excite a broader range of biomarkers by means of resonance.…”