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Gillespie NB, Wise KJ, Ren L, Stuart JA, Marcy DL, Hillebrecht J, Li Q, Ramos L, Jordan K, Fyvie S, Birge RR. Characterization of the Branched-Photocycle Intermediates P and Q of Bacteriorhodopsin. J Phys Chem B 2002. [DOI: 10.1021/jp021221p] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nathan B. Gillespie
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Kevin J. Wise
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Lei Ren
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Jeffrey A. Stuart
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Duane L. Marcy
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Jason Hillebrecht
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Qun Li
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Lavoisier Ramos
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Kevin Jordan
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Sean Fyvie
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
| | - Robert R. Birge
- Departments of Chemistry and of Molecular and Cell Biology, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269, and W. M. Keck Center for Molecular Electronics and Department of Chemistry, Syracuse University, 111 College Place, Syracuse, New York 13244-4100
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Kusnetzow A, Singh DL, Martin CH, Barani IJ, Birge RR. Nature of the chromophore binding site of bacteriorhodopsin: the potential role of Arg82 as a principal counterion. Biophys J 1999; 76:2370-89. [PMID: 10233056 PMCID: PMC1300211 DOI: 10.1016/s0006-3495(99)77394-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The nature of the chromophore binding site of light-adapted bacteriorhodopsin is analyzed by using modified neglect of differential overlap with partial single and double configuration interaction (MNDO-PSDCI) molecular orbital theory to interpret previously reported linear and nonlinear optical spectroscopic measurements. We conclude that in the absence of divalent metal cations in close interaction with Asp85 and Asp212, a positively charged amino acid must be present in the same vicinity. We find that models in which Arg82 is pointed upward into the chromophore binding site and directly stabilizes Asp85 and Asp212 are successful in rationalizing the observed one-photon and two-photon properties. We conclude further that a water molecule is strongly hydrogen bonded to the chromophore imine proton. The chromophore "1Bu*+" and "1Ag*-" states, despite extensive mixing, exhibit significantly different configurational character. The lowest-lying "1Bu*+" state is dominated by single excitations, whereas the second-excited "1Ag*-" state is dominated by double excitations. We can rule out the possibility of a negatively charged binding site, because such a site would produce a lowest-lying "1Ag*-" state, which is contrary to experimental observation. The possibility that Arg82 migrates toward the extracellular surface during the photocycle is examined.
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Affiliation(s)
- A Kusnetzow
- Department of Chemistry and W. M. Keck Center for Molecular Electronics, Syracuse University, Syracuse, New York 13244, USA
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Tallent JR, Stuart JA, Song QW, Schmidt EJ, Martin CH, Birge RR. Photochemistry in dried polymer films incorporating the deionized blue membrane form of bacteriorhodopsin. Biophys J 1998; 75:1619-34. [PMID: 9746505 PMCID: PMC1299835 DOI: 10.1016/s0006-3495(98)77605-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The preparation and photochemical properties of dried deionized blue membrane (dIbR600; lambdamax approximately 600 nm, epsilon approximately 54, 760 cm-1 M-1, f approximately 1.1) in polyvinyl alcohol films are studied. Reversible photoconversion from dIbR600 to the pink membrane (dIbR485; lambdamax approximately 485 nm) is shown to occur in these films under conditions of strong 647-nm laser irradiation. The pink membrane analog, dIbR485, has a molar extinction coefficient of approximately 39,000 cm-1 M-1 (f approximately 1.2). The ratio of pink --> blue and blue --> pink quantum efficiencies is 33 +/- 5. We observe an additional blue-shifted species (dIbR455, lambdamax approximately 455 nm) with a very low oscillator strength (f approximately 0.6, epsilon approximately 26,000 cm-1 M-1). This species is the product of fast thermal decay of dIbR485. Molecular modeling indicates that charge/charge and charge/dipole interactions introduced by the protonation of ASP85 are responsible for lowering the excited-state all-trans --> 9-cis barrier to approximately 6 kcal mol-1 while increasing the corresponding all-trans --> 13-cis barrier to approximately 4 kcal mol-1. Photochemical formation of both 9-cis and 13-cis photoproducts are now competitive, as is observed experimentally. We suggest that dIbR455 may be a 9-cis, 10-s-distorted species that partially divides the chromophore into two localized conjugated segments with a concomitant blue shift and decreased oscillator strength of the lambdamax absorption band.
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Affiliation(s)
- J R Tallent
- Department of Chemistry and W. M. Keck Center for Molecular Electronics, Syracuse University, Syracuse, New York 13244-4100 USA
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Maeda A, Asato AE, Liu RS, Yoshizawa T. Interaction of aromatic retinal analogues with apopurple membranes of Halobacterium halobium. Biochemistry 1984; 23:2507-13. [PMID: 6477881 DOI: 10.1021/bi00306a029] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Absorption spectral properties of aromatic analogues of retinal with apopurple membrane of Halobacterium halobium were studied. The spectra of the all-trans forms were composed of two or more absorption bands. During incubation at 20 degrees C, an absorption band above 500 nm increased in intensity gradually at the expense of an absorption band in the shorter wavelength region with no isomerization of the chromophore. The longer wavelength species was shown to be the protonated form of the shorter wavelength species by changing the pH of the medium. Upon irradiation with blue light, the bandwidth of the spectrum became smaller with isomerization of the chromophore to its 13-cis form. Irreversible binding of protons on the membrane occurred during this process. The rate of the increase in the longer wavelength absorption band was especially low in the reaction with the all-trans form of retinal analogues having a bulky substituent at the para or meta positions of the phenyl ring. In contrast, the 13-cis isomer of aromatic retinal analogues gave a single absorption peak. The extent of the spectral shift upon binding to apopurple membranes was compared over a series of aromatic retinals, and the results were explained in terms of steric interactions of the chromophore with the protein.
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Maeda A, Takeuchi Y, Yoshizawa T. Absorption spectral properties of acetylated bacteriorhodopsin in purple membrane depending on pH. Biochemistry 1982; 21:4479-83. [PMID: 7126552 DOI: 10.1021/bi00261a044] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The dark-adapted form of bacteriorhodopsin in the purple membrane of Halobacterium halobium changes its absorption maximum from 560 to 600 nm if the pH is lowered to about 2 [Oesterhelt, D., & Stoeckenius, W. (1971) Nature (London), New Biol. 233, 149; Moore, T. A., Edgerton, M. E., Parr, G., Greenwood, C., & Perham, R. N. (1978) Biochem. J. 171, 469; Mowery, P. C., Lozier, R. H., Chae, Q., Tseng, T.-W., Taylor, M., & Stoeckenius, W. (1979) Biochemistry 18, 4100; Fischer, U., & Oesterhelt, D. (1979) Biophys. J. 28, 211; Muccio, D. D., & Cassim, J. Y. (1979) J. Mol. Biol. 135, 595]. We compared the pH dependence of the absorption spectra of acetylated membrane with that of unacetylated native membrane. The completely acetylated membrane showed a midpoint of pH 4.8 for the conversion to the acidic form; that of the native membrane was 3.4. On acetylation, the absorption maximum at neutral pH moved from 560 to 555 nm with about 20% decreases in extinction coefficients as compared with that of the native membrane, whereas the spectrum in acid was not affected. The chloride-dependent blue shift from the acidic form of the acetylated membrane was largely suppressed. The CD spectrum of the acetylated membrane was composed of two bands of an opposite sign with slightly decreased amplitudes. The chromophore of the acetylated membrane was sensitive to hydroxylamine, and the spectrum before bleaching was restored on addition of all-trans-retinal to the bleached membrane followed by dark incubation. Blue light irradiation accelerated the conversion to the acidic form in the native membrane but not in the acetylated membrane. Reductive ethylation did not affect the pH dependence of the absorption spectra.
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