Carotenoids resonance Raman spectra

In order to obtain nearly absolute purity of the spectra of these xanthophylls, it was necessary to calculate the difference Raman spectra. Therefore, for zeaxanthin, two spectra of samples, one containing violaxanthin and the other enriched in zeaxanthin, were measured at 514.5 nm excitation. After their normalization using chlorophyll a bands at 1354 or 1389 cm-1, a deepoxidized-minus-epoxidized difference spectrum has for the first time been calculated to produce a pure resonance Raman spectrum of zeaxanthin in vivo (Figure 7.10b). A similar procedure was used for the calculation of the pure spectrum for violaxanthin. The only difference is that the 488.0nm excitation wavelength and epoxidized-minus-deepoxidized order of spectra have been applied in the calculation. The spectra produced using this approach have remarkable similarity to the spectra of xanthophyll cycle carotenoids in pure solvents (Ruban et al., 2001). The v, peaks of violaxanthin and zeaxanthin spectra are 7 cm 1 apart and in correspondence to the maxima of this band for isolated zeaxanthin and violaxanthin, respectively. The v3 band for zeaxanthin is positioned at 1003 cm-1, while the one for violaxanthin is upshifted toward 1006 cm-1. 

Resonance Raman Spectroscopy. A review of the interpretation of resonance Raman spectra of biological molecules includes a consideration of carotenoids and retinal derivatives. Another review of resonance Raman studies of visual pigments deals extensively with retinals. Excitation profiles of the coherent anti-Stokes resonance Raman spectrum of j8-carotene have been presented. Resonance Raman spectroscopic methods have been used for the detection of very low concentrations of carotenoids in blood plasma and for the determination of carotenoid concentrations in marine phytoplankton, either in situ or in acetone extracts. ... 

Infrared and Resonance Raman Spectroscopy. Reviewson the uses of resonance Raman spectroscopy in biochemistry and biology include sections on carotenoproteins, visual pigments, and bacteriorhodopsin. The resonance Raman spectrum of the lowest excited triplet state of /3-carotene has been reported.A resonance Raman method has been used for the quantitative analysis of /3-carotene and lutein (20) in tobacco.The mechanism of carotenoid-protein interactions in the carotenoproteins ovoverdin and /3-crustacyanin has been investigated by resonance Raman spectroscopy. " 2 axanthin (24) has been used as a resonance Raman probe of membrane structure. " The resonance Raman spectra have been reported of all-frans-anhydrovitamin A (194), " /3-ionone, retinals, and Schiff bases.The technique has been used extensively to study... 

Infrared and Raman Spectroscopy. Resonance Raman spectra of aW-trans- and 15-CW-/3-carotene have been compared.The ps resonance Raman spectrum of /8-carotene has been described,and solvent effects on the excitation profile of the line of jS-carotene have been studied. Model calculations have been used to interpret observed jS-carotene Raman spectra and excitation profiles. Raman scattering spectra of j8-carotene-l2 complexes have been determined. Resonance Raman spectra of carotenoids have been used as an intrinsic probe for membrane potential, e.g. neurosporene [7,8-dihydro-(/r,(/r-carotene (183)] in chromatophores of Rhodopseudomonas sphaeroides. ° Resonance Raman spectroscopy and i.r. spectroscopy have been used in studies of the chromophore of visual pigments and visual cycle intermediates and of bacteriorhodopsin and its photocycle intermediates. ... 

The v4 region enhancement and structure in the resonance Raman spectra of xanthophylls reviewed in this chapter shows that it can be used for the analysis of carotenoid-protein interactions. Figure 7.8 summarizes the spectra for all four major types of LHCII xanthophylls. Lutein 2 possesses the most intense and well-resolved v4 bands. The spectrum for zeaxanthin is very similar to that of lutein with a slightly more complex structure. This similarity correlates with the structural similarity between these pigments. It is likely that they are both similarly distorted. The richer structure of zeaxanthin spectrum may be explained by the presence of the two flexible P-end rings... 

In a novel experiment, Koyama et al. (57) obtained a spectrum of carotenoid BLM by resonance Raman spectroscopy—a major advance in BLM spectroscopy. For efficient charge transfer, the orientation of chlorophyll molecules at the membrane-solution interface is important. Brasseur et al. (58) developed a procedure for conformation analysis to define the position of chlorophyll in BLM. They found that the porphyrin ring is orientated at an angle of 45 5° to the plane of the BLM, which is in excellent agreement with the value reported previously (44). 

Thus far, only the range of UV and visible wavelengths has been reported. In this connection Koyama et al. obtained a spectrum of carotenoid-BLM by resonance Raman spectroscopy, which should be considered as a major advance in BLM spectroscopy. 

A modified mechanism has been proposed for formation of the M—92 and M—106 ions in the mass spectra of carotenoids (see Scheme 1). Further resonance-enhanced laser Raman spectra of retinal derivatives have been reported.A comparison between various semi-empirical methods for the calculation of -carotene MO s has appeared. A better correlation between the u.v. spectrum and theoretical predictions is claimed by Suzuki et... 

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