Chlorophyll Mixtures Research Articles

Modulating spectral response of raw photosynthetic pigments via ternary cadmium chalcogenide quantum dots: simultaneous enhancement at green spectrum and inhibition at UV region.

Photosynthesis relies on the absorption of sunlight by photosynthetic pigments (PPs) such as chlorophylls and carotenoids. While these pigments are outstanding at harvesting light, their natural structure restricts their ability to harvest light at specific wavelengths. In this study, Oleic acid-capped CdSeS and CdTeS ternary quantum dots (QDs) were synthesized using a novel two-phase synthesis method. Then, these QDs were used to interact with raw PPs, a mixture of chlorophylls and carotenoids isolated from spinach. Our findings revealed the following: (1) Interacting QDs with raw PPs effectively inhibited the chlorophyll fluorescence of the pigments upon excitation in UV light region (250-400nm) without causing any damage to their structure. (2) By forming an interaction with QDs, the chlorophyll fluorescence of raw PPs could be induced through excitation with green-light spectrum. (3) The composition of the QDs played a fundamental role in their interaction with PPs. Our study demonstrated that the photophysical properties of isolated PPs could be modified by using cadmium-based QDs by preserving the structure of the pigments themselves.

Development and characterization of chlorophyll-amended montmorillonite clays for the adsorption and detoxification of benzene

After disasters, such as forest fires and oil spills, high levels of benzene (> 1 ppm) can be detected in the water, soil, and air surrounding the disaster site, which poses a significant health risk to human, animal, and plant populations in the area. While remediation methods with activated carbons have been employed, these strategies are limited in their effectiveness due to benzene's inherent stability and limited retention to most surfaces. To address this problem, calcium and sodium montmorillonite clays were amended with a mixture of chlorophyll (a) and (b); their binding profile and ability to detoxify benzene were characterized using in vitro, in silico, and well-established ecotoxicological (ecotox) bioassay methods. The results of in vitro isothermal analyses indicated that chlorophyll-amended clays showed an improved binding profile in terms of an increased binding affinity (Kf = 668 vs 67), increased binding percentage (52% vs 11%), and decreased rates of desorption (28% vs 100%), compared to the parent clay. In silico simulation studies elucidated the adsorption mechanism and validated that the addition of the chlorophyll to the clays increased the adsorption of benzene through Van der Waals forces (i.e., aromatic π-π stacking and alkyl-π interactions). The sorbents were also assessed for their safety and ability to protect sensitive ecotox organisms (Lemna minor and Caenorhabditis elegans) from the toxicity of benzene. The inclusion of chlorophyll-amended clays in the culture medium significantly reduced benzene toxicity to both organisms, protecting C. elegans by 98–100% from benzene-induced mortality and enhancing the growth rates of L. minor. Isothermal analyses, in silico modeling, and independent bioassays all validated our proof of concept that benzene can be sequestered, tightly bound, and stabilized by chlorophyll-amended montmorillonite clays. These novel sorbents can be utilized during disasters and emergencies to decrease unintentional exposures from contaminated water, soil, and air.

Selective voltammetric detection of chlorophylls using a semi-circular potential wave

A simple electrochemical method employing a novel semi-circular potential sweep voltammetry on a glassy carbon (GC) electrode was developed to distinguish and quantify two main chlorophyll components (chlorophyll a and b) present in their mixtures. The semi-circular potential sweep generates large, transient scan rates, enabling the selective detection of species with closely similar oxidative potentials. The proposed method shows good applicability in mixtures of chlorophyll a (Chl a) and chlorophyll b (Chl b) with concentrations ranging from 46.2 to 110.8 μM and 46.2 to 92.4 μM respectively, which were prepared to mimic varying compositions of chlorophyll a and b in nature for the application in food quality control. The method was successfully applied to real sample of spinach.

Performance improvement of dye-sensitized solar cells (DSSC) by using dyes mixture from chlorophyll and anthocyanin

This article showed the effect of single and mixture natural dyes on the DSSC performance. The single dyes extracted from moss chlorophyll and mangosteen peels anthocyanin. The dyes mixture was prepared by mixing from both chlorophyll and anthocyanin. The absorbance of dyes solution and the adsorption of the dye onto the working electrode were analyzed using UV-Vis spectroscopy. The photocurrent-photovoltage of DSSCs were measured using I-V meter. The dyes mixture has an increased absorption at visible spectrum range as compared to single dye. The adsorption of the dyes mixture onto the TiO2 electrode has higher absorbance than single dye. The DSSC with single dye from moss chlorophyll and mangosteen peels anthocyanin resulted the conversion efficiency of 0.049% and 0.042% respectively. The dyes mixture of chlorophyll and anthocyanin improved the conversion efficiency of 0.154%.

Extraction, preparation and application of pigments from Cordyline fruticosa and Hylocereus polyrhizus as sensitizers for dye-sensitized solar cells

Current study employs mixture of chlorophyll-anthocyanin dye extracted from leaves of Cordyline fruticosa as new sensitizers for dye-sensitized solar cell (DSSCs), as well as betalains dye obtained from fruit of Hylocereus polyrhizus. Among ten pigments solvents, the ethanol and methanol extracts revealed higher absorption spectra of pigments extracted from C. fruticosa and H. polyrhizus respectively. A major effect of temperature increase was studied to increase the extraction yield. The results indicated that extraction temperature between 70 and 80°C exhibited a high dye concentration of each plant than other temperatures. The optimal temperature was around 80°C and there was a sharp decrease of dye concentration at temperatures higher than this temperature. According to experimental results, the conversion efficiency of DSSC fabricated by mixture of chlorophyll and anthocyanin dyes from C. fruticosa leaves is 0.5% with short-circuit current (Isc) of 1.3mA/cm−2, open-circuit voltage (Voc) of 0.62V and fill factor (FF) of 60.16%. The higher photoelectric conversion efficiency of the DSSC prepared from the extract of H. polyrhizus was 0.16%, with Voc of 0.5V, Isc of 0.4mA/cm−2 and FF of 79.16%. The DSSC based betalain dye extracted from fruit of H. polyrhizus shows higher maximum IPCE of 44% than that of the DSSCs sensitized with mixed chlorophyll-anthocyanin dye from C. fruticosa (42%).

Early folding events during light harvesting complex II assembly in vitro monitored by pulsed electron paramagnetic resonance

Efficient energy transfer in the major light harvesting complex II (LHCII) of green plants is facilitated by the precise alignment of pigments due to the protein matrix they are bound to. Much is known about the import of the LHCII apoprotein into the chloroplast via the TOC/TIC system and its targeting to the thylakoid membrane but information is sparse about when and where the pigments are bound and how this is coordinated with protein folding. In vitro, the LHCII apoprotein spontaneously folds and binds its pigments if the detergent-solubilized protein is combined with a mixture of chlorophylls a and b and carotenoids. In the present work, we employed this approach to study apoprotein folding and pigment binding in a time-resolved manner by using pulsed electron paramagnetic resonance (EPR). Intra-molecular distances were measured before folding, after 255ms and 40s folding time in the absence of cryoprotectant, and in the fully folded and assembled LHCII. In accordance with earlier results, the most of the folding of the three membrane-spanning alpha helices precedes their apposition into the final tertiary structure. However, their formation follows different kinetics, partially extending into the final phase of LHCII formation during which much of the condensation of the pigment-protein structure occurs, presumably governed by the binding of chlorophyll b. A rough timetable is proposed to sort partial events into the LHCII formation process.

Effect of TiO 2 blocking layer synthesised by a sol–gel method in performances of fluorine‐doped tin oxide/TiO 2 /dyed‐TiO 2 /electrolyte/pt/fluorine‐doped tin oxide solar cells based on natural mallow dye

Titanium dioxide (TiO2) thin film prepared by sol–gel technique and deposed by spin coating was used as the blocking layer between fluorine doped tin oxide and dyed TiO2 photoanode deposed by doctor blade in dye-sensitised solar cell (DSSC). The synthesised films show a polycrystalline structure at annealing temperature of 400°C with small amount of amorphous phase observed at 300°C. The values of the electrical conductivity varies from 0.11 to 1.17 Ω−1 cm−1 for one and two layers thin films, respectively, and the corresponding activation energies decreased as a function of the thickness, it passes from 109 meV for one layer to 55 meV for two layers. The photoanode of the DSSC was sensitised by the mallow diluted in ethanol having absorption spectra with two peaks, one around 480 nm (blue light) and the second at 665 nm (red light) attributable to the chlorophyll mixture. Improvement of the electrical performance is due to the increased electron lifetime and decreased of the recombination process showed by the open circuit voltage decay measurement. The lifetime values increase from 0.80 ms for the cell without blocking layer to 1.24 ms for the cell based on the blocking layer.

CHEMICAL CONCEPTS IN MOTION: THE ROLE OF COLLECTIVE SCHEMES ON THE LEARNING ABOUT INTERMOLECULAR INTERACTIONS

The purpose of this research is to access data related to how College students collectively develop structural schemes during the resolution of experimental problems of investigative nature. This research included two situations presented to six students in the Undergraduate and Teacher’s Licensure Chemistry Course at the Federal University of ABC (Brazil) involving Liquid Chromatography contents. The students were divided into groups and asked to make a decision about the best experimental conditions to separate a mixture of chlorophyll, xanthophyll and -carotene in spinach extract. They possessed different stationary phases and elements. The students’ explanations were recorded on an audio-visual device and analysed via computer assisted qualitative data analysis software (CAQDAS) supported by the Transana software. As a result, evidence of the collective development of a scheme characterized by conceptual relations pertinent to the structural field was identified; however, such evidence was incomplete. The interference of the teacher in the students’ decision making was a relevant factor during the resolution of the problems. Conceptual and logical operations of thinking (operative invariants) gaps may be an opportunity for a pedagogical intervention during the resolution of problems in the classroom. Keywords: Theory of Conceptual Fields, collective schemes, intermolecular interactions.

Ratios, proportions, and mixtures of chlorophylls: Corrections to spectrophotometric methods and an approach to diagnosis

Ratios of absorbances at two wavelengths have been used to quantify mixtures of photosynthetic pigments such as chlorophylls, phaeophytins and bacteriochlorophylls, however published methods have either specified an incorrect relationship between the absorbance ratio and the mixture, or only presented the relationship graphically. The correct relationship is established along with correct forms for equations to calculate pigment densities from absorbance ratios. The limitations of simple ratios and a diagnostic approach using difference spectra are illustrated with an example involving mixtures of oxygenic and anoxygenic phytoplankton communities in a stratified lake.

ОПТИМИЗАЦИЯ УСЛОВИЙ ВЫДЕЛЕНИЯ ХЛОРОФИЛЛОВ ИЗ КРАПИВЫ ДВУДОМНОЙ (URTICA DIOICA L.) И СПИРУЛИНЫ (SPIRULINA PLATENSIS)

Various factors as the nature of the solvent, temperature, presence or absence of stirring and sonication, affecting the efficiency of extractive separation of the two chlorophylls from two plant sources – a flowering plant of nettle (Urtica dioica L.), containing a mixture of chlorophyll a and b, and the blue-green alga spirulina (Spirulina platensis), containing only chlorophyll a, are compared in a paper. The aim of the work was to optimize the conditions for the allocation of chlorophyll from plant material.

A new probe for tracking the presence of E141i food colorant

HPLC/APCI-MS was applied to the characterization of copper pyropheophytin a, the main chlorophyllic derivative present in E141i, a marketed copper chlorophyll mixture used legally for addition of green hues in food products. Exceptionally, its use is banned in Europe and America for fats and oils and consequently, the characterization of copper pyropheophytin a by HPLC/MS is critical for olive oil control adulteration and also essential for the detection of this colorant in colored foodstuffs. The MS2 of copper pyropheophytin a shows four fragment ions arising from the loss of phytadiene, a product ion corresponding to the loss of the complete propionic unit at C17, and product ions corresponding to the loss of phytol and additional methyl groups at D ring. This last fragmentation reaction means the description by first time of the opening of the D ring, showing a new fragmentation pathway where to fit product ions of other chlorophyll derivatives not explained up to now and being an ideal probe for tracking the use of colorant E141i in foods.

Photostability of photosynthetic complexes coupled to silver nanowires

We investigate the influence of plasmonic excitations in silver nanowires upon the photostability of photosynthetic complex placed at their vicinity. Strong interaction between the two nanostructures is evident through increase of the fluorescence intensity of the photosynthetic complexes close to the nanowires as compared to uncoupled ones and shortening of the fluorescence lifetime. Analysis of movies collected using a wide-field fluorescence microscope with respect to temporal intensity variations for photosynthetic complexes located along and at the ends of the nanowires, indicate that the photostability is unaffected by the interaction with plasmonic excitations in metallic nanoparticles. Therefore, we conclude that in the case of studied hybrid nanostructures coupling with metallic nanoparticles results in higher number of photons emitted from chlorophyll molecules. Full Text: PDF References R.E. Blankenship, Wiley-Blackwell, ISBN: 978-0-632-04321-7 (2002). Ł. Bujak, N. Czechowski, D. Piatkowski, R. Litvin, S. Mackowski, T.H.P. Brotosudarmo, R.J. Cogdell, S. Pichler, W. Heiss, "Fluorescence enhancement of light-harvesting complex 2 from purple bacteria coupled to spherical gold nanoparticles", Appl. Phys. Lett. 99, 173701 (2011). CrossRef N. Czechowski, P. Nyga, M.K. Schmidt, T.H.P. Brotosudarmo, H. Scheer, D. Piatkowski, S. Mackowski, "Absorption Enhancement in Peridinin–Chlorophyll–Protein Light-Harvesting Complexes Coupled to Semicontinuous Silver Film", Plasmonics 7, 115 (2012). CrossRef J.B. Nieder, R. Bittl, M. Brecht, "Fluorescence Studies into the Effect of Plasmonic Interactions on Protein Function", Angew. Chem. Int. Ed. 49, 10217 (2010). CrossRef A. O. Govorov, I. Carmeli, "Hybrid Structures Composed of Photosynthetic System and Metal Nanoparticles:  Plasmon Enhancement Effect", Nano Letters 7, 620 (2007). CrossRef M. Olejnik, B. Krajnik, D. Kowalska, M. Twardowska, N. Czechowski, E. Hofmann, S. Mackowski, "Imaging of fluorescence enhancement in photosynthetic complexes coupled to silver nanowires", Appl. Phys. Lett. 102, 083703/1 (2013). CrossRef P. Anger, P. Bharadwaj, L. Novotny, "Enhancement and Quenching of Single-Molecule Fluorescence", Phys. Rev. Lett. 96, 113002 (2006). CrossRef J.R. Lakowicz, "Radiative Decay Engineering: Biophysical and Biomedical Applications", Analytical Biochemistry 298(1), 1 (2001). CrossRef K. Ray, R. Badugu, J.R. Lakowicz, "Metal-Enhanced Fluorescence from CdTe Nanocrystals:  A Single-Molecule Fluorescence Study", J. Am. Chem. Soc. 128, 8998 (2006). CrossRef S. Mackowski, S. Wörmke, A.J. Maier, T.H.P. Brotosudarmo, H. Harutyunyan, A. Hartschuh, A.O. Govorov, H. Scheer, C. Bräuchle, "Metal-Enhanced Fluorescence of Chlorophylls in Single Light-Harvesting Complexes", Nano Letters 8, 558 (2008). CrossRef A.D. Ferguson, E. Hofmann, J. W. Coulton, K. Diederichs, W. Welte, "Siderophore-Mediated Iron Transport: Crystal Structure of FhuA with Bound Lipopolysaccharide", Science 282, 2215 (1998). CrossRef K.E. Korte, S.E. Skrabalak, Y. Xia, "Rapid synthesis of silver nanowires through a CuCl- or CuCl 2 -mediated polyol process", J. Mater. Chem. 18, 437 (2008). CrossRef T.H.P. Brotosudarmo, E. Hofmann, R.G. Hiller, S. Wörmke, S. Mackowski, A. Zumbusch, C. Bräuchle, H. Scheer, "Peridinin–chlorophyll–protein reconstituted with chlorophyll mixtures: Preparation, bulk and single molecule spectroscopy", FEBS Letters 580, 5257 (2006). CrossRef

Colloidal nanocrystal ZnO- and TiO2-modified electrodes sensitized with chlorophyll a and carotenoids: a photoelectrochemical study

Heterostructures formed of films of organic-capped ZnO and TiO2 nanocrystals (both with the size of ca. 6 nm) and photosynthetic pigments were prepared and characterized. The surface of optically transparent electrodes (Indium Tin Oxide) was modified with nanocrystals and prepared by colloidal synthetic routes. The nanostructured electrodes were sensitized by a mixture of chlorophyll a and carotenoids. The characterization of the hybrid structures, carried out by means of steady-state optical measurements, demonstrated such class of dyes able to extend the photoresponse of the large band-gap semiconductors. The charge-transfer processes between the components of the heterojunction were investigated, and photoelectrochemical measurements taken on the sensitized ZnO and TiO2 nanocrystals electrodes elucidated the photoactivity of the heterojunctions as a function of the dyes and of the red–ox mediator used in solution. The effect of methyl viologen as different red–ox mediator was also evaluated in order to show its effect on the heterojunction photoactivity. The overall results contributed to describe the photoelectrochemical potential of the investigated heterojunctions, highlighting a higher response of the dye-sensitized ZnO nanocrystals, and then provided the TiO2-modified counterparts.

Enhancement of lipase catalyzed-fatty acid methyl esters production from waste activated bleaching earth by nullification of lipase inhibitors

This study sought to identify inhibitory factors of lipase catalyzed-fatty acid methyl esters (FAME) production from waste activated bleaching earth (wABE). During the vegetable oil refinery process, activated bleaching earth (ABE) is used for removing the impure compounds, but adsorbs vegetable oil up to 35–40% as on a weight basis, and then the wABE is discarded as waste material. The impurities were extracted from the wABE with methanol and evaluated by infra-red (IR) spectroscopy, which revealed that some were chlorophyll-plant pigments. The chlorophylls inhibited the lipase during FAME conversion from wABE. The inhibition by a mixture of chlorophyll a and b was found to be competitive. The inhibition of the enzymatic hydrolysis of waste vegetable oil contained in wABE by chlorophyll a alone was competitive, while the inhibition by chlorophyll b alone was non-competitive. Furthermore, the addition of a small amount of alkali nullified this inhibitory effect and accelerated the FAME production rate. When 0.9% KOH (w/w wABE) was added to the transesterification reaction with only 0.05% lipase (w/w wABE), the maximum FAME production rate improved 120-fold, as compared to that without the addition of KOH. The alkali-combined lipase significantly enhanced the FAME production rate from wABE, in spite of the presence of the plant pigments, and even when a lower amount of lipase was used as a catalyst.

Energy Transfer in the Peridinin-Chlorophyll Protein Complex Reconstituted with Mixed Chlorophyll Sites

We use femtosecond transient absorption spectroscopy to study chlorophyll (Chl)-Chl energy transfer in the peridinin-chlorophyll protein (PCP) reconstituted with mixtures of either chlorophyll b (Chlb) and Chld or Chla and bacteriochlorophyll a (BChla). Analysis of absorption and transient absorption spectra demonstrated that reconstitution with chlorophyll mixtures produces a significant fraction of PCP complexes that contains a different Chl in each domain of the PCP monomer. The data also suggest that binding affinity of Chla is less than that of the other three Chl species. By exciting the Chl species lying at higher energy, we obtained energy transfer times of 40±5ps (Chlb-Chld) and 59±3ps (Chla-BChla). The experimental values match those obtained from the Förster equation, 36 and 50ps, respectively, showing that energy transfer proceeds via the Förster mechanism. Excitation of peridinin in the PCP complex reconstituted with Chla/BChla mixture provided time constants of 2.6 and 0.4ps for the peridinin-Chla and peridinin-BChla energy transfer, matching those obtained from studies of PCP complexes reconstituted with single chlorophyll species.

Multispectral and hyperspectral analysis and modelling of the absorbance characteristics of marine algal pigments

The techniques of remote sensing in spectral bands and hyperspectral remote sensing were modelled with laboratory experiments on marine algal pigments obtained from four species of green micro‐algae of the eastern coast of India. The spectral absorbance was measured within the visible range of wavelength for chlorophyll mixtures of different concentrations and also for chromatographically separated pigments. The intention was to simulate and compare the expected nature of results obtained with remote sensing in wavebands and hyperspectral sensing involving a fine resolution in wavelength. Therefore, the absorbance was measured both with filters of three different visible spectral bands, viz. blue, green, and red, and with a continuous scan of wavelength. The algal species were distinguishable with both types of measurements. However, the hyperspectral technique was found to be more suitable in revealing the individual contribution of pigments. Based on the experimental results, a computational model was developed with Gaussian variation of absorbance as a function of wavelength. The experimental results were simulated with that model explaining the comparative spectroscopic results obtained from band and hyperspectral sensing.

Relative binding affinities of chlorophylls in peridinin–chlorophyll–protein reconstituted with heterochlorophyllous mixtures

Peridinin-chlorophyll-protein (PCP), containing differently absorbing chlorophyll derivatives, are good models with which to study energy transfer among monomeric chlorophylls (Chls) by both bulk and single-molecule spectroscopy. They can be obtained by reconstituting the N-terminal domain of the protein (N-PCP) with peridinin and chlorophyll mixtures. Upon dimerization of these "half-mers", homo- and heterochlorophyllous complexes are generated, that correspond structurally to monomeric protomers of native PCP from Amphidinium carterae. Heterochlorophyllous complexes contain two different Chls in the two halves of the complete structure. Here, we report reconstitution of N-PCP with binary mixtures of Chl a, Chl b, and [3-acetyl]-Chl a. The ratios of the pigments were varied in the reconstitution mixture, and relative binding constants were determined from quantification of these pigments in the reconstituted PCPs. We find higher affinities for both Chl b and [3-acetyl]-Chl a than for the native pigment, Chl a.

Monitoring fluorescence of individual chromophores in peridinin–chlorophyll–protein complex using single molecule spectroscopy

Single molecule spectroscopy experiments are reported for native peridinin–chlorophyll a–protein (PCP) complexes, and three reconstituted light-harvesting systems, where an N-terminal construct of native PCP from Amphidinium carterae has been reconstituted with chlorophyll (Chl) mixtures: with Chl a, with Chl b and with both Chl a and Chl b. Using laser excitation into peridinin (Per) absorption band we take advantage of sub-picosecond energy transfer from Per to Chl that is order of magnitude faster than the Förster energy transfer between the Chl molecules to independently populate each Chl in the complex. The results indicate that reconstituted PCP complexes contain only two Chl molecules, so that they are spectroscopically equivalent to monomers of native-trimeric-PCP and do not aggregate further. Through removal of ensemble averaging we are able to observe for single reconstituted PCP complexes two clear steps in fluorescence intensity timetraces attributed to subsequent bleaching of the two Chl molecules. Importantly, the bleaching of the first Chl affects neither the energy nor the intensity of the emission of the second one. Since in strongly interacting systems Chl is a very efficient quencher of the fluorescence, this behavior implies that the two fluorescing Chls within a PCP monomer interact very weakly with each other which makes it possible to independently monitor the fluorescence of each individual chromophore in the complex. We apply this property, which distinguishes PCP from other light-harvesting systems, to measure the distribution of the energy splitting between two chemically identical Chl a molecules contained in the PCP monomer that reaches 280 cm − 1 . In agreement with this interpretation, stepwise bleaching of fluorescence is also observed for native PCP complexes, which contain six Chls. Most PCP complexes reconstituted with both Chl a and Chl b show two emission lines, whose wavelengths correspond to the fluorescence of Chl a and Chl b. This is a clear proof that these two different chromophores are present in a single PCP monomer. Single molecule fluorescence studies of PCP complexes, both native and artificially reconstituted with chlorophyll mixtures, provide new and detailed information necessary to fully understand the energy transfer in this unique light-harvesting system.

Peridinin–chlorophyll–protein reconstituted with chlorophyll mixtures: Preparation, bulk and single molecule spectroscopy

Reconstitution of the 16 kDa N-terminal domain of the peridinin–chlorophyll–protein, N-PCP, with mixtures of chlorophyll a (Chl a) and Chl b, resulted in 32 kDa complexes containing two pigment clusters, each bound to one N-PCP. Besides homo-chlorophyllous complexes, hetero-chlorophyllous ones were obtained that contain Chl a in one pigment cluster, and Chl b in the other. Binding of Chl b is stronger than that of the native pigment, Chl a. Energy transfer from Chl b to Chl a is efficient, but there are only weak interactions between the two pigments. Individual homo- and hetero-chlorophyllous complexes were investigated by single molecule spectroscopy using excitation into the peridinin absorption band and scanning of the Chl fluorescence, the latter show frequently well resolved emissions of the two pigments.

Reconstitution of the Peridinin–chlorophyll a Protein (PCP): Evidence for Functional Flexibility in Chlorophyll Binding

The coding regions for the N-domain, and full length peridinin-chlorophyll a apoprotein (full length PCP), were expressed in Escherichia coli. The apoproteins formed inclusion bodies from which the peptides could be released by hot buffer. Both the above constructs were reconstituted by addition of a total pigment extract from native PCP. After purification by ion exchange chromatography, the absorbance, fluorescence excitation and CD spectra resembled those of the native PCP. Energy transfer from peridinin to Chl a was restored and a specific fluorescence activity calculated which was approximately 86% of that of native PCP. Size exclusion analysis and CD spectra showed that the N-domain PCP dimerized on reconstitution. Chl a could be replaced by Chl b, 3-acetyl Chl a, Chl d and Bchl using the N-domain apo protein. The specific fluorescence activity was the same for constructs with Chl a, 3-acetyl Chl a, and Chl d but significantly reduced for those made with Chl b. Reconstitutions with mixtures of chlorophylls were also made with eg Chl b and Chl d and energy transfer from the higher energy Qy band to the lower was demonstrated.