Bacteriorhodopsin Raman spectroscopy

The use of picosecond pulses to minimize the Interference of fluorescence with the Raman spectrum was also demonstrated (5) at about that time. The use of vldicon detection in Raman spectroscopy was demonstrated (6) in 1976. The first resonance Raman spectrum taken for a photobiologlcal system (bacteriorhodopsin) in the nanosecond time scale was (7) in 1977. The resonance Raman spectra of bacteriorhodopsin have also been measured in the microsecond (8,9,10) and in the millisecond (11) time domain. Recently the time resolved resonance Raman spectra of photolyzed hemoglobin derivatives have been reported (12). 

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... 

Schiffs base, but the spectra for the M-412 intermediate indicate that this proton is lost. The deprotonation of the Schiffs base is apparently after the K intermediate [262], and proposed to be during the L to M transition [209,263,264], Reprotonation of the nitrogen is suggested to occur during the M-412 to 0-640 conversion [265], Part of the blue-shift in the formation of M-412 is, of course, explained by the fact that, in model retinal compounds, loss of the proton leads to a 440-380 nm shift [266], but other effects must also be present. Circumstantial evidence, which includes the finding of 13-cis retinal in M-like intermediates stabilized under somewhat denaturing conditions [198,267], favors the idea that the retinal is isomerized in the M intermediate, as do the more direct resonance Raman data [268,269], In fact, the K and L intermediates seem already to contain the 13-c/i isomer of retinal, as indicated by extraction of 13-c/i retinal from the L intermediate [270] and spectroscopic data on the K and L intermediates [271-274], The resonance Raman spectroscopy of bacteriorhodopsin photointermediates has been recently reviewed [275],... 

Pollard WT, Dexheimer S L, Wang Q, Peteanu L A, Shank C V and Mathies R A 1992 Theory of dynamic absorption spectroscopy of nonstationary states. 4. Application to 12 fs resonant Raman spectroscopy of bacteriorhodopsin J. Phys. Chem. 96 6147-58... 

Figure 4 illustrates the kind of information that can be obtained with time-resolved resonance Raman spectroscopy by presenting picosecond resonance Raman spectra of the bacteriorhodopsin chromophore. The data have been used to determine the structure of the J and K intermediates as well as to provide information about an intermediate between K and L. ... 

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. ... 

Applications of solid state NMR along with FTIR and Raman spectroscopy and X-ray crystallography to study the structural changes in the proton transport cycle of the light-driven pump, bacteriorhodopsin, have been reviewed by Laniy. " ... 

Raman spectroscopy has been particularly useful in studies of rhodopsin and bacteriorhodopsin. As discussed in Chap. 4, excitatirai of rhodopsin or bacteriorho-dopsin by light causes isomerization of the retinyl chromophore. In rhodopsin, the chromophore changes from W-cis to all-trans in bacteriorhodopsin, it goes from dA -trans to 13-cA. Resonance Raman measurements showed that the isomerization is essentially complete in metastable intermediate states that form within a few ps [32-38]. The conformations of these states were ascertained by comparisons of the resonance Raman spectra with those of model compounds. 

Doig, S.J., Reid, P.J., Mathies, R.A. Picosecond time-resolved resmiance Raman spectroscopy of bacteriorhodopsin-J, bacteriorhodopsin-K, bacfcaioihodopsin-KL intermediates. J. Phys. Chem. 95, 6372-6379 (1991)... 

The kinetics of the photoisomerization of bilirubin has been studied because of the relevance to phototherapy. The fluorescence of bilirubin increases on binding to human serum albumin. This and other primary photoprocesses have been investigated by picosecond spectroscopy. Karvaly has put forward a new photochemical mechanism for energy conversion in bacteriorhodopsin. An extensive review of the photophysics of light transduction in rhodopsin and bacteriorhodopsin has been made by Birge. The dynamics of cis-trans isomerization in rhodopsin has been analysed by INDO-CISD molecular orbital theory. Similar calculations on polyenes and cyanine dyes have also been reported. A new picosecond resonance Raman technique shows that a distorted... 

Infrared spectroscopy (IR) has not been extensively used in retinoid analysis (17,18). However, the newer techniques of Resonance Raman and infrared-difference spectroscopy have been applied to retinal proteins m rhodopsin and bacteriorhodopsin. By use of these techniques, it is possible to determine the structures of the chromophores m the visual pigments and in the intermediates of their photoreactions Also, it is possible to study the interactions between the chromophores and the protein, and the structural changes evoked in the protein by the photoreaction (1,19). 

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