Near‐infrared‐excitation resonance Raman spectra of bacterial photosynthetic reaction centers Implications for path‐specific electron transfer

Bocian, David F.; Boldt, Nancy J.; Chadwick, Barry W.; Frank, Harry A.

doi:10.1016/0014-5793(87)80019-4

Cited by 45 publications

(29 citation statements)

References 26 publications

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“…However, resonance Raman excitation in this region is a difficult task, not only because of the laser wavelengths required but also because of interference from fluorescent impurities, which can only be eluded by extensive purification. 21 Resonance Raman spectra of RCs have been reported with UV excitation in the Soret and Qx bands of BChl and BPh. 2 Resonance Raman excitation at 752.8 nm, in resonance width the Qy band of bacteriopheophytin, has also been reported.…”

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confidence: 99%

Fourier Transform Raman Spectroscopy of Photoactive Proteins with Near-Infrared Excitation

Johnson

Rubinovitz

1990

Appl Spectrosc

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The Fourier transform (FT) Raman spectroscopic treatment of the photoactive proteins bacteriorhodopsin and the photosynthetic reaction center is reported, with excitation at 1.06/~m. Excitation at this wavelength circumvents the limitations on resonance Raman spectroscopy of these proteins imposed by their photolability and by the fluorescence of free pigments or impurities. The spectra are dominated by nonresonant Raman scattering by the protein-bound pigments retinal (in bacteriorhodopsin) and bacteriopheophytin, bacteriochlorophyll, and carotenoids (in reaction centers). The relative intensities of retinylidene modes in the spectrum for nonresonant FT Raman spectroscopy of bacteriorhodopsin are nearly identical to those observed in the resonance Raman spectrum of bacteriorhodopsin.

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Section: Resultsmentioning

confidence: 99%

Fourier Transform Raman Spectroscopy of Photoactive Proteins with Near-Infrared Excitation

Johnson

Rubinovitz

1990

Appl Spectrosc

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“…We conclude therefore that the slower The fraction containing [3-vinyl]-132-OH-BChl-a at site BA is called [3-vinyl]RCs. (27)(28)(29) and its potential functional importance in photosynthesis (30)(31)(32)(33) [3-vinyl]BChl-a at the monomeric site BA while -35% of the RCs have BChl-a at this position.tt The fraction containing [3-vinyl]BChl-a at site BA exhibits a slower decay of the excited electronic level P* (X' 32 ps). The additional observation of a long-lasting bleaching of the Q.…”

Section: P+b P+h-p+q- This Model Ismentioning

confidence: 99%

Primary electron transfer kinetics in bacterial reaction centers with modified bacteriochlorophylls at the monomeric sites BA,B.

Finkele

Lauterwasser

Struck

et al. 1992

Proc. Natl. Acad. Sci. U.S.A.

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The primary electron transfer has been investigated by femtosecond time-resolved absorption spectroscopy in two chemically modified reaction centers (RC) of Rhodobacter sphaeroides, in which the monomeric bacteriochlorophylls BA and BB have both been exchanged by 132-hydroxybacteriochlorophyll a or [3-vinylJ-132-hydroxybac-teriochlorophyll a. The kinetics of the primary electron transfer are not influenced by the 132-hydroxy modification. In RCs containing [3-vinyl]-132-hydroxybacteriochlorophyll a the primary rate is reduced by a factor of 10. HThe three known x-ray structures of bacterial reaction centers (RCs) show basically the same arrangement of the cofactors (see refs. 1-4). They form two branches [A (active) and B (inactive)], which are arranged in an approximate twofold symmetry. Surprisingly, the electron transfer (ET) has been found to proceed exclusively along the A branch (5-7). From the primary donor, P870 or P960, an electron is transferred to the acceptor quinone (QA) The structural arrangement of the chromophores suggests an ET via the two intervening pigments-i.e., the monomeric bacteriochlorophyll (BChl) BA and the bacteriopheophytin (BPhe) HAWhile there is general agreement that the BPhe HA is an intermediate electron acceptor (5-9), the role of the BChl BA located between the BChl dimer P and the BPhe HA is still controversially discussed. First studies with sufficient time resolution and an appropriate excitation wavelength led to the conclusion that the state P+B-(P, primary donor) is not a real intermediate in the ET (5,10,11). However, a direct ET from P* to HA over an edge-to-edge distance of '10 A can be accounted for only by a "superexchange" transfer via a virtual intermediate P+B-(12-15 Kinetic measurements were performed at T 298 K in cuvettes of 1-mm path length under stirring. The sample volume was 0.2-0.3 ml. The transmission was between T 10%o and 50% at A = 860 nm (80-25 ,uM The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

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“…sphaeroides (Clayton and Clayton, 1981). In the latter case, the decrease again has been shown to be due not to loss of any pigment but to a detergent effect (Chadwick et al, 1987).…”

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“…sphaeroides (Clayton and Clayton, 1981). In the latter case, the decrease again has been shown to be due not to loss of any pigment but to a detergent effect (Chadwick et al, 1987).The first attempt to exchange pigments into native or partially denatured reaction centers (Method 4) is likely to be that published by Loach et al (1975), who worked on the so-called alcaline urea-triton XI00 (AUT) particles of Rhodospirillum (Rs.) rubrum.…”

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Bacterial Reaction Centers with Modified Tetrapyrrole Chromophores

Scheer¹,

Struck

1993

Photosynthetic Reaction Center

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II. Norris, James R., Date. QP517.P45P46 1993 '3342-dc20 92-43633This book is printed on acid-free paper.© Academic Press, Inc. References 78 Genetic Analysis of Photosynthetic Membrane Biogenesis in Rhodobacter sphaeroides I. IntroductionSeveral different methods are available for preparing reaction centers with nonnative chromophores: (1) (re)assembly from the Polypeptides, pigments, and other components such as quinones, iron, and possibly others; (2) exchange of chromophores into native or partly denatured reaction centers; (3) modification of chromophores in native or partly denatured reaction centers by chemical or enzymatic means; (4) modification of binding sites to incorporate different chromophores, for example, by mutagenesis, and (5) mutagenic modifications of the pigments biosynthetic pathways. With the exception of the last one, all these approaches have been used on different Complete reconstitution of the complexes (Method 1) from the isolated constituent Polypeptides and suitably modified pigments is likely to have the greatest potential, but to date has been impossible with reaction centers. This technique has been applied successfully to the core light-harvesting complexes (LHCI) of purple bacteria (Miller et al, 1987;Ghosh et al, 1988;Parkes-Loach et al, 1988 Chang et al, 1990a,b;Heller and Loach, 1990) and to the peripheral light-harvesting chromoprotein LHCII-ß of higher plants (Plumley and Schmidt, 1987). The method has been extended by Paulsen etat. (1990Paulsen etat. ( ,1991 to the full-length and modified LHCII-ß precursor Polypeptides expressed in and isolated from Escherichia coli and by Schmidt et al. (1991) to other green plant peripheral light-harvesting complexes.Site-directed mutagenesis of the binding pockets (Method 4) has been used extensively to exchange bacteriochlorophylls (Behls) with their metalfree derivatives, for example, bacteriopheophytins (Bphes) and vice versa in reaction centers (RCs) from Rhodobacter (Rb.) capsulatus and Rb. sphaeroides (Table I)-With only a Single exception, whenever the histidine(s) ligating the central magnesium atom(s) of the Bchl(s) were replaced by hydrophobic amino acids, stably assembled RCs were obtained in which the Behls at the respective site(s) were replaced by Bphe to yield stably assembled and isolatable RCs (Bylina and Youvan, 1988; Coleman and Youvan, 1990;Robles et al, 1990;Schenck et al, 1990;Woodbury et al, 1990). In reversing this reaction, replacement of leucine or isoleucine next to the central N-4 cavity of Bphe with histidine resulted in binding of Behl at the respective site. Some results are available with amino acid residues of intermediate ligation strength. Serine or threonine selected binding of Behl at BA and BB (Bylina et al, 1990); glutamine (mutants H-L173Q and H-M200Q 2 ) at the sites of the special pair resulted in binding of Behl also (Bylina and Youvan, 1988). Omission of Bphe HL was found in a mutant of Rb. capsulatus in which part of the D helix of subunit L was replaced by the symmetrically equiv...

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Near‐infrared‐excitation resonance Raman spectra of bacterial photosynthetic reaction centers Implications for path‐specific electron transfer

Cited by 45 publications

References 26 publications

Fourier Transform Raman Spectroscopy of Photoactive Proteins with Near-Infrared Excitation

Fourier Transform Raman Spectroscopy of Photoactive Proteins with Near-Infrared Excitation

Primary electron transfer kinetics in bacterial reaction centers with modified bacteriochlorophylls at the monomeric sites BA,B.

Bacterial Reaction Centers with Modified Tetrapyrrole Chromophores

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