Carotenoid Band Research Articles

Detecting photosynthetic algal pigments in natural populations using a high-spectral-resolution spectroradiometer

Reflectance data from a high spectral resolution spectroradiometer were obtained onboard a ship in Plymouth coastal waters. These data were analysed to detect algal photosynthetic accessory pigments for comparison with absorption spectra as measured in the laboratory by a spectrophotometer. The overall spectral characteristics of Plymouth waters allowed identification as to population composition. Derivative analysis of the spectra was used to resolve characteristic peaks of specific pigments. It was determined that chlorophyll pigments, a specific carotenoid and sea water absorption bands were detectable in the reflectance data. Absorption bands of photosynthetic and accessory pigments were assessed through chromatographic pigment analysis.

Supramolecular organization of the photosynthetic apparatus of Rhodobacter sphaeroides.

Native tubular membranes were purified from the purple non-sulfur bacterium Rhodobacter sphaeroides. These tubular structures contain all the membrane components of the photosynthetic apparatus, in the relative ratio of one cytochrome bc1 complex to two reaction centers, and approximately 24 bacteriochlorophyll molecules per reaction center. Electron micrographs of negative-stained membranes diffract up to 25 A and allow the calculation of a projection map at 20 A. The unit cell (a = 198 A, b = 120 A and gamma = 103 degrees) contains an elongated S-shaped supercomplex presenting a pseudo-2-fold symmetry. Comparison with density maps of isolated reaction center and light-harvesting complexes allowed interpretation of the projection map. Each supercomplex is composed of light-harvesting 1 complexes that take the form of two C-shaped structures of approximately 112 A in external diameter, facing each other on the open side and enclosing the two reaction centers. The remaining positive density is tentatively attributed to one cytochrome bc1 complex. These features shed new light on the association of the reaction center and the light-harvesting complexes. In particular, the organization of the light-harvesting complexes in C-shaped structures ensures an efficient exchange of ubihydroquinone/ubiquinone between the reaction center and the cytochrome bc1 complex.

Application of FT-Raman spectroscopy to an ecological study of the lichen Xanthoparmelia scabrosa in the supralittoral zone, Hong Kong

FT-Raman spectra of the foliose lichen Xanthoparmelia scabrosa sampled from ten supralittoral sites in Hong Kong have been obtained and the relative intensities of nine key vibrational features have been monitored. The relative intensity of the ν(CC) carotenoid band at c. 1525 cm −1 changes by up to 400% between sites and that of the ν(CC) aromatic ring stretching at c. 1000 cm −1 by 100% between sites. A multivariate analysis of the Raman spectra and environmental indicators, such as heavy metals, was carried out and the effects of these indicators on the spectral bands is assessed. No evidence was found in the spectra for hydrated calcium oxalate or incorporation of the substratal material. In the case of other lichen species studied the presence of crystalline α-quartz in the thalli was identified using Raman spectroscopy; this indicated that possibly a physical rather than chemical biodeteriorative strategy operated for these species.

Ultrafast carotenoid band shifts probe structure and dynamics in photosynthetic antenna complexes.

We report observations of ultrafast carotenoid band shifts correlated with energy transfer dynamics between bacteriochlorophyll (BChl) molecules within the peripheral light-harvesting complex (LH2) from the photosynthetic bacterium Rhodobacter sphaeroides. Direct excitation of the bacteriochlorophyll Qy bands yielded distinct changes in the carotenoid S2 absorption from 430 to 530 nm. Transient absorption spectra and kinetics were measured in a femtosecond pump-probe experiment, revealing the ultrafast carotenoid response to excited BChl pigments. These data are an indication of a new property of carotenoids that is manifested as a unique ability to detect and report changes in their immediate environment, thereby serving as sensitive probes of local structure and dynamics.

Analysis of Anti-Stokes Resonance Raman Excitation Profiles as a Method for Studying Vibrationally Excited Molecules

Anti-Stokes and Stokes resonance Raman excitation profiles have been observed for the CC and C−C stretching fundamental bands of carotenoids (β-carotene and canthaxanthin) and analyzed on the basis of the Franck−Condon mechanism. It is shown that such an analysis provides a method for identifying the vibrational levels on which vibrationally excited molecules observed in picosecond pump−probe processes are populated.

Electric Field Effects of Photogenerated Ion Pairs on Nearby Molecules: A Model for the Carotenoid Band Shift in Photosynthesis

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectric Field Effects of Photogenerated Ion Pairs on Nearby Molecules: A Model for the Carotenoid Band Shift in PhotosynthesisDavid Gosztola, Hiroko Yamada, and Michael R. WasielewskiCite this: J. Am. Chem. Soc. 1995, 117, 7, 2041–2048Publication Date (Print):February 1, 1995Publication History Published online1 May 2002Published inissue 1 February 1995https://doi.org/10.1021/ja00112a018RIGHTS & PERMISSIONSArticle Views331Altmetric-Citations54LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (912 KB) Get e-Alerts Get e-Alerts

Roles of the soluble cytochrome c2 and membrane-associated cytochrome cy of Rhodobacter capsulatus in photosynthetic electron transfer.

Genetic evidence indicates that Rhodobacter capsulatus has two different pathways for reduction of the photooxidized reaction center (RC) [Jenney, F. E., & Daldal, F. (1993) EMBO J. 12, 1283-1292]. One pathway is via the water soluble cytochrome (cyt) c2, and the other is via a novel, membrane-associated c-type cytochrome, cyt cy, now believed to be identical to the cyt cx of Jones et al. [Jones, M. R., et al. (1990) Biochim. Biophys. Acta 975, 59-66] and c354 of Zannoni et al. [Zannoni, D., et al. (1992) Arch. Microbiol. 157, 367-374]. Mutants lacking either cyt c2, cyt cy, or the bc1 complex, as well as various combinations, were utilized to probe the functional role of these cytochromes in electron transfer. Data obtained by monitoring flas induced electron transfer kinetics in the RC, cyt c pool, cyt b, and the carotenoid band shift indicate that there are two pathways for electron transfer from the bc1 complex to the RC in R. capsulatus, one via cyt c2 and the other through cty cy. The two pathways show strikingly different kinetics for RC reduction and cyt c oxidation, and both are present in the wild-type strain MT-1131. After genetic inactivation of both cyt c2 and cyt cy there remains no flash oxidizible c-type cytochrome, and inactivation of cyt cy rather than cyt c2 has a more pronounced effect on the extent of the light-induced membrane potential under the conditions tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrochromic responses of carotenoid absorbance bands in purified light-harvesting complexes from Rhodobacter capsulatus reconstituted into liposomes

Light-Harvesting Complexes I and II (LHI and LHII) were extracted from chromatophores of Rhodobacter capsulatus, purified in Triton X-100 and reconstituted into phospholipid vesicles. Application of membrane potentials (K + diffusion potentials) to LHII proteoliposomes led to absorbance changes in the carotenoid bands which were spectrally similar to those in chromatophores. These (electrochromic) absorbance changes were linear with the applied membrane potential between −107 mV and +105 mV. The data were consistent with the existence of two forms of carotenoid in LHII. One form, comprising 2 3 of the total and with a long wavelength absorbance maximum at 510 nm, was not significantly affected by membrane potential. The other component, comprising 1 3 of the total and with a long wavelength absorbance maximum at 516.5 nm, was shifted by approx. 1.6 nm to the red by a membrane potential of 105 mV. Reduction of the B800 bacteriochlorophyll in LHII with NaBH 4 before reconstitution did not affect the absorbance spectrum of the carotenoids and it did not affect their response to applied membrane potentials in proteoliposomes. Although the electrochromically-sensitive carotenoids might be associated with B800, interactions with the bacteriochlophyll are perhaps not the cause of the polarisation of the carotenoid that is responsible for the linearity of the response. The carotenoids in reconstituted LHI complexes were not detectably electrochromic. The electrochromic absorbance changes of carotenoids in LHII could be useful for membrane potential measurement in liposomes containing ion-translocating proteins.

Electrochromic behaviour of carotenoid molecules in nerve cell membranes: A resonance Raman study

It was found that, following the depolarization of cell membranes of frog sciatic nerve, the 1521 and 1156 cm −1 resonance Raman (RR) bands of carotenoids showed an increase in intensity of 20%, 15% and 4% at excitation wavelengths of 488, 496.5 and 514.5 nm respectively. None of the bands revealed any change with excitation at 441.6, 457.9, 472.7 and 476.5 nm. These results can be explained by an electrochromic shift of the excitation profile of the RR bands by about 0.5 nm to the red. A dependence of the 1521 cm −1 band intensity on transmembrane potential was obtained. Under the effect of lanthanum ions, which are known to modify the surface charge of the membrane, the intensity of the Raman bands decreased by 150%–20% (excitation, 488.0 nm). The results obtained indicate that RR spectroscopy of carotenoids can be used to monitor changes in the transmembrane potential and surface charge of nerve cell membranes.

Photo-oxidation of reaction center-bound cytochrome c and generation of membrane potential determined by carotenoid band shift in the purple photosynthetic bacterium, Rhodospirillum molischianum

The purple photosynthetic bacterium Rhodospirillum molischianum has a cytochrome c subunit bound to the reaction center (RC). Redox titration of the cytochrome c showed the presence of a high-potential heme peaked at 558 nm in the α-absorption band region, with an E m (redox midpoint potential) value of 390 mV, and three low-potential hemes peaked at 552 nm, with E m values below 100 mV. The extent of flash-induced membrane potential, measured by the carotenoid band shift in chromatophores, varied depending on which heme was photo-oxidized at the ambient redox potential. If the extent of membrane potential is proportional to the distance of electron movement, the heme with highest potential, c-558, is assumed to be located in the most distant position from the special pair of bacteriochlorophyll in Rs. molischianum. Kinetic measurements of photo-oxidations of hemes, however, suggested that the highest potential heme is at the nearest position in Rs. molischianum, as in the case of Rhodopseudomonas viridis. We propose a model in which the magnitude of the membrane potential depends not only on the distance of electron movement across the membrane but also on the dielectric property in the cytochrome subunit which can be largely affected by the distance of the redox centers from the protein-aqueous interface. According to this model, the highest potential heme, c-558, is estimated to be proximal to the special pair and also to the aqueous surface, so that the largest electrostatic potential change occurs upon its photo-oxidation.

Large Protein-Induced Dipoles for a Symmetric Carotenoid in a Photosynthetic Antenna Complex

Unusually large electric field effects have been measured for the absorption spectra of carotenoids (spheroidene) in the B800-850 light-harvesting complex from the photosynthetic bacterium Rhodobacter sphaeroides. Quantitative analysis shows that the difference in the permanent dipole moment between the ground state and excited states in this protein complex is substantially larger than for pure spheroidene extracted from the protein. The results demonstrate the presence of a large perturbation on the electronic structure of this nearly symmetric carotenoid due to the organized environment in the protein. This work also provides an explanation for the seemingly anomalous dependence of carotenoid band shifts on transmembrane potential and a generally useful approach for calibrating electric field-sensitive dyes that are widely used to probe potentials in biological systems.

Fluorescence of the reaction centre of photosystem II in cells of green alga Chlamydomonas reinhardtii

Cells of green alga Chlamydomonas reinhardtii, mutant ASS66, which only exhibit the spectra and polypeptide composition of photosystem II, possess a weak fluorescence at about 673 nm along with two main emission bands at 686 and 698 nm, after cultivation in the dark. The 673 nm fluorescence exhibits an excitation spectrum similar to the absorbance of the isolated reaction centre of photosystem II (D1/D2 protein complex). It contains chlorophyll a, pheophytin a, and carotenoid bands with the chlorophyll:pheophytin ratio of about 3. Under illumination, the intensity of the 673 nm emission band decreases with concomitant increase in the emission band at 698 nm, which is thought to belong to the core antenna of photosystem II. Under illumination, in the presence of dithionite (strong reducing conditions), the relative intensity of 673 to 686 nm emission does not change, but the intensities of the pheophytin bands in its excitation spectrum were reduced two-fold. That the relative intensity of the 673 nm band in the emission spectrum under illumination in the presence of dithionite does not change indicates that it originates from an emitter other than pheophytin (possibly reaction centre chlorophyll a).

Involvement of cytochrome bc1 complex in the electron transfer pathway for N 2O reduction in a photodenitrifier, Rhodobacter sphaeroides f. s. denitrificans

The electron transfer pathway for N 2O reduction in Rhodobacter sphaeroides f. s. denitrificans was studied. Myxothiazol and antimycin showed inhibiting effects on the consumption of N 2O in whole cells grown under photo-denitrifying conditions. This indicated the involvement of the cytochrome bc 1 complex in the process. Reduced redox dyes that donate electrons directly to cytochrome c 2 overcame this inhibition. Similar results were obtained with Rhodobacter capsulatus, in contrast to earlier studies by McEwan et al. [(1985) J. Bacteriol. 164, 823–830] that suggested the lack of involvement of the cytochrome bc 1 complex in this process. Effects of myxothiazol and antimycin were also observed on the N 2O-induced oxidation of cytochromes c 1 and c 2 and on the simultaneous generation of membrane potential measured by the carotenoid band shift. Thus, reducing equivalents for N 2O reduction from substrates pass through the cytochrome bc 1 complex coupling to the generation of an electrochemical gradient of protons.

Evaluation of the electrical capacitance in biological membranes at different phospholipid to protein ratios

Photosynthetic chromatophores of Rhodobacter capsulatus were differently enriched in phospholipid content by freezing, thawing and sonicating in the presence of phospholipid vesicles. Closed vesicles, characterized by different phospholipid to protein molar ratios and increasing average radius at increasing phospholipid enrichment, were collected after sucrose density gradient sedimentation. The electrical capacitance of these systems was evaluated from the ratio of reaction center content, photooxidized by single turnover flash in the presence of antimycin, to the corresponding membrane potential difference, measured from the electrochromic red shift of the endogenous carotenoid band. The values obtained, normalized per protein content, increased at increasing phospholipid enrichment, and correlated linearly with the increasing phospholipid to protein molar ratios. The charging capacitance of chromatophores was evaluated to be 3–6×10-17 F and was found to increase at increasing average radius of the phospholipid enriched vesicles, as predicted by the equation of the spherical shell dielectric. The carotenoid signal, elicited in the dark by imposing diffusion potentials of known extent with K+-valinomycin pulses, significantly decreased at high phospholipid enrichment, indicating that in the presence of large phospholipid excess, a partial displacement of the carotenoid molecules sensing the induced electric field is produced. Concomitantly, the energy transfer efficiency from carotenoids to core light harvesting complexes (B-875) was also partially affected, particularly at high phospholipid to protein molar ratio. All together, these results suggest that the reaction center complexes are dispersed within the lipid bilayer upon fusion and that carotenoids sense a delocalized light-induced transmembrane field.

The effects of lithium dodecyl sulfate and sodium borohydride on the absorption spectrum of the B800–850 light-harvesting complex from Rhodopseudomonas acidophila 7750

The effects of the detergent lithium dodecyl sulfate and the reducing agent sodium borohydride on the absorption spectrum of the B800–850 light-harvesting complex from Rhodopseudomonas acidophila 7750 were determined. Treatment of B800–850 complex with 0.1% lithium dodecyl sulfate results in an approx. 85% attenuation of the bacteriochlorophyll absorption band at 800 nm and 2–4 nm red-shifts of the bacteriochlorophyll absorption bands at 590 nm and 857 nm and a 4 nm blue-shift of the carotenoid absorption bands. Treatment with sodium borohydride resulted in an attenuation of the bacteriochlorophyll absorption band at 800 nm, a 1 nm red-shift of the bacteriochlorophyll 857 nm absorption band and an attenuation of the carotenoid bands. A comparison of the effects suggests that lithium dodecyl sulfate induces a nonspecific change in the antenna complex, possibly a protein conformational change whereas sodium borohydride chemically modifies both bacteriochlorophyll and carotenoid. The spectral changes are interpreted in terms of alterations in the pigment interactions which are responsible for the native absorption properties of B800–850 complexes.

Effect of the action potential on the Raman spectrum of the pike olfactory nerve

Raman bands due to the CH stretching vibrations of the phospholipid acyl chains, as well as those due to resonance enhanced vibrations of carotenoid pigments, were used to probe for conformational changes during the passage of the action potential through fibers of the pike unmyelinated olfactory nerve. Our results show that if there are any spectral changes during nerve excitation, these are less than 0.5% for both the phospholipid and the carotenoid bands.

Comparative spectral studies of pigmented organs and tissues of two cladocera species

1. 1. The microspectrophotometric technique was applied for in vivo investigation of Cladocera pigmented organs and tissues. 2. 2. It was shown that the visible coloration of the Cladocera tissues and organs results from combination of absorption bands of myoglobin, carotenoids and carotene-protein with various intensities. 3. 3. The absorption spectra of Cladocera egg carotene-protein, ovoverdin, in vivo contain a single absorption band with the maximum wavelength of about 650 nm.

Discrete catalytic sites for quinone in the ubiquinol-cytochrome c2 oxidoreductase of Rhodopseudomonas capsulata. Evidence from a mutant defective in ubiquinol oxidation.

A non-photosynthetic mutant (Ps-) of Rhodopseudomonas capsulata, designated R126, was analyzed for a defect in the cyclic electron transfer system. Compared to a Ps+ strain MR126, the mutant was shown to have a full complement of electron transfer components (reaction centers, ubiquinone-10, cytochromes b, c1, and c2, the Rieske 2-iron, 2-sulfur (Rieske FeS) center, and the antimycin-sensitive semiquinone). Functionally, mutant R126 failed to catalyze complete cytochrome c1 + c2 re-reduction or cytochrome b reduction following a short (10 microseconds) flash of actinic light. Evidence (from flash-induced carotenoid band shift) was characteristic of inhibition of electron transfer proximal to cytochrome c1 of the ubiquinol-cytochrome c2 oxidoreductase. Three lines of evidence indicate that the lesion of R126 disrupts electron transfer from quinol to Rieske FeS: 1) the degree of cytochrome c1 + c2 re-reduction following a flash is indicative of electron transfer from Rieske FeS to cytochrome c1 + c2 without redox equilibration with an additional electron from a quinol; 2) inhibitors that act at the Qz site and raise the Rieske FeS midpoint redox potential (Em), namely 5-undecyl-6-hydroxy-4,7-dioxobenzothiazole or 3-alkyl-2-hydroxy-1,4-napthoquinone, have no effect on cytochrome c1 + c2 oxidation in R126; 3) the Rieske FeS center, although it exhibits normal redox behavior, is unable to report the redox state of the quinone pool, as metered by its EPR line shape properties. Flash-induced proton binding in R126 is indicative of normal functional primary (QA) and secondary (QB) electron acceptor activity of the photosynthetic reaction center. The Qc functional site of cytochrome bc1 is intact in R126 as measured by the existence of antimycin-sensitive, flash-induced cytochrome b reduction.

Evidence for regulation in vivo of the ATP synthase in intact cells of the photosynthetic bacterium Rhodopseudomonas capsulata

(1) The cytoplasmic membrane potential (Δψ) of intact cells of Rhodopseudomonas capsulata, measured either from the uptake of butyltriphenylphosphonium cation or from the electrochromic carotenoid band shift, increased upon illumination (negative on the cytoplasmic side) and then, within the next 20 s, partly declined while the light was still on. In the presence of the F 0 inhibitor venturicidin the light-induced Δψ was increased by 30% and the partial decline was abolished. (2) From the ionic current/Δψ curves for the bacterial membranes it was concluded that the slow, partial decline of Δψ after the onset of illumination was the result of an increase in membrane conductance. The conductance increase seen in the ionic current/Δψ curves was blocked by venturicidin suggesting that it was caused by increased proton flux through the ATP synthase. (3) Analysis of the light-induced changes in adenine nucleotide levels in intact bacterial cells showed that the apparent increase in ATP synthase activity was not the result of a decrease in phosphorylation potential. The data were consistent with either an increase in the catalytic activity of the ATP synthase or with an increase in H + flux through the enzyme without a proportionate increase in the rate of phosphorylation (increased ‘slip’). (4) This slow change in the properties of the ATP synthase, as judged by the venturicidin-sensitive partial decline of Δψ, required a minimum initial value of Δψ. When Δψ was reduced, either by decreasing the actinic light intensity or by adding carbonylcyanide trifluoromethoxyphenylhydrazone the partial decline in Δψ was abolished. (5) The slow change in ATP synthase properties reversed upon darkening the bacterial cell suspension. A second illumination period shortly after the first elicited a smaller initial Δψ and a smaller Δψ decline. The relaxation of the ATP synthase in the dark was measured from the dependence of the initial increase in Δψ after the second illumination period upon the dark-time between the two illumination periods.

Absorbance changes of carotenoids and bacteriochlorophylls responding to the change of local electrical field induced by hydrophobic anion, tetraphenylborate in membranes of photosynthetic bacteria

Large blue-shifts of carotenoid absorption bands were induced by dark addition of a hydrophobic anion, tetraphenylborate, in chromatophores and cell membranes of photosynthetic bacteria, Rhodopseudomonas sphaeroides and Rhodopseudomonas capsulata. Tetraphenylborate also induced a red-shift of the 850 nm absorption band and a blue-shift and broadening of the 800 nm band of bacteriochlorophyll. From the analysis of the relation between the magnitude and isosbestic wavelength of the absorbance changes the tetraphenylborate-induced carotenoid band shift were assumed to reflect the change of local electrical field close to each carotenoid molecule which exists as a minor pool on the light-harvesting pigment-protein complex II (LHC II). Absorbance changes of carotenoid and chlorophylls were also induced by tetraphenylborate in membranes of spinach chloroplasts.