Bacteriorhodopsin resonance Raman spectrum

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... 

Fig. 3. Resonance Raman spectrum of the all-trani-retinal protonated Schiff base chromo-phore in light-adapted bacteriorhodopsin. The assignments are of the various enhanced vibrational normal modes are indicated. (From Smith el al. )...

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. ... 

Early experiments with bacteriorhodopsin (228) interpreted the Raman spectrum in terms of an unprotonated Schiff base, forming a charge-transfer complex with a protein functional group (210,212). This interpretation of the Raman data, essentially based on a comparison with the frequencies of model Schiff bases in solution, was criticized by Honig and Ebrey (48), who pointed out that consistency could also be obtained with a protonated Schiff base model. The latter hypothesis was subsequently confirmed by deuteration experiments similar to those described for rhodopsin (229,230), and by Raman spectra in denatured systems (231). In variance with the clear-cut similarity observed between the resonance-Raman spectra of rhodopsin and isorhodopsin, and those of the 11-cis and 9-cis model compounds, respectively,... 

Fig. 5. Millisecond time-resolved UV resonance Raman spectra of bacteriorhodopsin. Spectrum A was obtained with a 240 nm probe beam in the presence of a 515 nm pump beam that converts a fraction of the sample over to the M intermediate. Spectrum B was obtained with just the 240 nm probe beam. The various difference spectra present the changes in structure of the resonantly enhanced tyrosines and tryptophans that occur during the conversion to the M intermediate. (From Ames et alP ...

One can dso obtain NMR spectra for proteins in micelles, which may allow the study of membrane protein structure in an environment approximating their native one. A combination of labels (l N,13c) was used for NMR studies of detergent-solubilized M13 coat protein. Although most of die resonances in the spectrum have not been assigned, there was clear indication that many of the protein residues had two distinct resonances of equal intensity. This was interpreted to mean (in combination with the results of sedimentation equilibrium, Raman and CD studies) that the protein was present in two conformers that represent the non-equivalent monomers of an asymmetric dimer. NMR has also been used to determine the spatial structures of gramicidin A and -labeled bacteriorhodopsin fragments in a membrane-like milieu b... 

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