Resonance Raman spectroscopy of bacteriorhodopsin

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... 

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See also in sourсe #XX -- [ ]

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