Properties and potential applications of bioconjugates of R-phycoerythrin with Ag° or CdS nanoparticle synthesized in its tunnel cavity: A review.

Green synthesis is a promising method for the preparation of nanoparticles (NPs) due to its simplicity, low cost, low toxicity, and environmental friendliness. Biosynthesized NPs exhibit multifunctional activity, good biocompatibility, and higher anticancer and antibacterial activity compared to chemically synthesized NPs. R-phycoerythrin, a photosynthetic light-harvesting pigment of protein nature (M.

Two Distinct Photoprocesses in Cyanobacterial Bilin Pigments: Energy Migration in Light-Harvesting Phycobiliproteins versus Photoisomerization in Phytochromes.

The evolution of oxygenic photosynthesis, respiration and photoperception are connected with the appearance of cyanobacteria. The key compounds, which are involved in these processes, are tetrapyrroles: open chain - bilins and cyclic - chlorophylls and heme. The latter are characterized by their covalent bond with the apoprotein resulting in the formation of biliproteins.

Ag Nanoparticles Synthesized in R-phycoerythrin: Change in Bioconjugate Properties upon Ripening of Nanoparticles.

Background: Bioconjugates prepared from photoactive molecules and metal nanoparticles are suitable for the development of new optoelectronic devices and for theranostic applications in medicine.

Methods: We produced a bioconjugate of R-phycoerythrin (R-PE), a photosynthetic pigment of red algae, with Ag0 nanoparticles (Ag0 NPs) synthesized in its tunnel cavities by mixing aqueous solutions of AgNO3 and R-PE without exogenous reductant. In freshly prepared bioconjugate (Ag0⋅R-PE), the diameter of Ag0 NPs measured in electron microscopic images was 6.

The Photovoltaic Effect of CdS Quantum Dots Synthesized in Inverse Micelles and R-Phycoerythrin Tunnel Cavities.

CdS quantum dots (CdS QDs) 4.3 nm in diameter synthesized in an AOT/isooctane/water microemulsion and in R-phycoerythrin tunnel cavities (3.5 × 6.

Structural changes in R-phycoerythrin upon CdS quantum dot synthesis in tunnel cavities of protein molecules.

Structural changes in R-phycoerythrin used as a matrix for the synthesis of CdS quantum dots have been analyzed by circular dichroism spectrometry. In deionized water, quantum dot synthesis in the tunnel cavity of the R-phycoerythrin molecule proved to be accompanied by uncoiling of α-helices and changes in the conformation of its chromophore groups, with consequent decay of protein fluorescence. Since R-phycoerythrin fluorescence is important for practical applications, conditions for quantum dot synthesis have been optimized by replacing deionized water with 0.

Effect of cadmium sulfide quantum dots on physical properties of R-phycoerythrin as a protein matrix.

The synthesis and analysis of nanostructures in the cavities of protein molecules is a promising research field in the industry of nanosystems. In this study, atomic force microscopy (AFM) has been used to evaluate the properties of CdS quantum dots synthesized in the tunnel cavities of R-phycoerythrin, a 290 kDa water-soluble pigment protein responsible for light harvesting in red algae. It has been shown that R-phycoerythrin dissolved in deionized water to a concentration of 50 μg/ml is prone to self-organization into regular spatial structures upon adsorption on the surface of mica, but no such structuring takes place in films prepared from R-phycoerythrin solutions diluted tenfold.

[R-phycoerythrin: a natural ligand for detoxifying cadmium ions and a tunnel matrix for synthesis of cadmium sulfide nanoparticles].

As evidenced by ion-selective electrode potentiometry, the hexameric R-phycoerythrin (RPE) molecule binds 20-4000 cadmium ions (Cd2+) depending on Cd2+ concentration in the solution. Cadmium ions bound to RPE serve as nuclei of cadmium sulfide crystallization in the presence of sulfide ions. According to spectrometric, electron-microscopic and capillary electrophoresis data, the particles are heteroaggregates of 3.

[Effect of cadmium on the absorption and excitation energy transfer in cyanobacterium Nostoc muscorum].

The absorption and energy transfer between pigments in Nostoc muscorum by the action of 10(-4) M Cd2+, when the cyanobacterium remains viable, and in the presence of 10(-3) M Cd2+, which causes the death of cells during 3-4 weeks of incubation, were studied. A comparative study by the methods of absorption and fluorescence spectrophotometry at 295 and 77 K, including derivative spectroscopy and deconvolution of emission spectra into a number of Gaussian components, showed that, in the presence of 10(-4) M Cd2+, the energy transfer from phycobilisomes to chlorophyll of photosystem I increased. After incubation with 10(-3) M Cd2+, the energy transfer from phycobilisomes to chlorophyll of photosystem II decreased, and the transfer to photosystem I was absent.

[Participation of extracellular polysaccharides in detoxication of cadmium ions by cyanobacteria Nostoc muscorum].

Using the methods of absorption and fluorescence spectroscopy, histochemistry and micrography, the influence of cadmium in different concentrations on the exudation of exopolysaccharides by Nostoc muscorum was studied to elucidate the possibility of distance detoxication of cadmium ions by the cyanobacterium with the participation of its exometabolites. The toxic action of Cd was controlled by changes in biomass, trichomes morphology, and the photosynthetic apparatus of the cyanobacterium. The content of exopolysaccharides in the extracellular medium was 0.

[Photochemistry of phycobilisomes: photosensitized reduction of methylviologen].

The ability of phycobilisomes (PBS) to photosensitize the reduction of methylviologen by dithiothreitol has been shown. This reaction has been studied in dependence on the structural integrity of PBS, nature and pH of the medium, and concentration of reagents. The action spectrum of the reaction has been measured, and its quantum yield has been detected.

[Energy migration in phycobilisomes].

Fluorescence emission and polarization spectra of the phycobilisomes (PBS) of the blue-green alga Nostoc muscorum were measured at 20, -73 and -196 degrees C while exciting at the absorption maximum of each pigment in the PBS. The emission spectra were deconvoluted into a number of Gaussian components and energy migration coefficients and quantum yields of fluorescence for the 8 forms of the phycobilins constituting the PBS were calculated. The overlap integrals and the critical and real distances for the energy transfer in the donor-acceptor pairs were evaluated.

[Fractionation of phycobilisomes from the blue-green alga Nostoc muscorum].

Phycobilisomes (PBS) isolated from Nostoc muscorum contain eight spectral forms of phycobiliproteins. PBS partially dissociated by osmotic or temperature shock, were separated into 42S and 34S particles by centrifugation in sucrose density gradient. The 42S particles are enriched with phycocyanin, the 34S ones--with allophycocyanin.

[Adenylate kinase activity of phycobilisomes from the blue-green algae Microcystis aerogenosa].

The phycobilisomes (PBS) from the blue-green algae Microcystis aerogenosa was found to possess the adenylate kinase activity. The enzyme activity of PBS is kept for 2 weeks, reaching its maximum on th 2nd-4th day after PBS isolation from the cells, and is retained after passage of freshly isolated PBS through a column with Sephadex G-25. The adenylate kinase activity of PBS is thermostable, depends on the protein concentration in the sample, undergoes activation by white light and is inhibited by glutaric aldehyde.

[Dark and photo-induced changes in absorption and fluorescence spectra of phycobilisomes in the presence of dithionite].

In order to test the possibility of photochemical participation of phycobilin pigments in photosynthesis, the ability of phycobilisomes for reversible photo-induced redox reactions was studied. The photo-induced fast reversible changes in the absorption and fluorescence spectra of phycobilisomes in the presence of dithionite were found. Simultaneously dithionite induced dark changes revealed by the decrease of the absorption and fluorescence yields.

[Effectiveness of excitation energy migration in the phycobilisomes of red marine macroalgae].

Phycobilisomes (PBS) were isolated from talloms of sea red macroalgae: annual Gloiopeltis furcata from illuminated and shaded shoal and perennial Ahnfeltia tobuchiensis. The spectral changes have shown that R-phycoerythrin, phycocyanin, allophycocyanin, allophycocyanin B were contained in PBS of the algae under study. The efficiency of energy migration to the ultimate acceptor-allophycocyanin B is twice as low in Ahnfeltia tobuchiensis (0.

[Resolution of the structure of the absorption spectrum of blue-green algae by a method of measuring the 2d derivative at -196 degrees C].

By measuring the 2nd derivative at -196 degrees C the thin structure of the absorption spectrum of intact cells, isolated in phycobilisomes and pure pigments of blue-green algae Anabaena variabilis and Aphanizomanon flos-aquae is shown. 8 absorption bands in the region 669--710 nm pertaining to chlorophyll a in different aggregation region were found. Almost the same number of bands were found in the region 550--660 nm.

Phycobilisomes from the blue-green algae Aphanizomenon flos-aquae and Anabaena variabilis.

Phycobilisomes (PBS) were isolated from Aphanizomenon flos-aquae and Anabaena variabilis. The absorption spectra and second derivative of the absorption spectra of isolated PBS indicate the presence of phycoerythrocyanin, and allophycocyanin. The fluorescence spectra of PBS were measured at room temperature and -196 degrees C.

The photosensitizing action of phycobiliproteins in the adsorbed state.

In connection with the elucidation of the possibility of photochemical participation of phycobiliproteins in the primary processes of photosynthesis, the ability of a mixture of phycocyanin + allophycocyanin (PC + APC) for photosensitization of redox reactions in the adsorbed state was investigated. It was shown that adsorbates of PC + APC on Sephadexes G-200 and G-25, diethylaminoethylcellulose, carboxyethylcellulose, Bacto-agar, Lifogel, polyethylene glycol, Dowex 50Wx2, and aluminum oxide are capable of sensitizing the photoreduction of methyl red by ascorbid acid. In this case the effectiveness of the sensitizing action depends on the concentration of the adsorbate, the pigment concentration on the carrier, the pH of the medium, and the nature of the solvent.

[Role of phycobilin pigments in photosynthesis].

Experimental data on possible role of phicobilliprotein (PhBP) in photosynthesis are analysed. It is concluded that the widely spread notion about PhBP only as the light-gathering pigments which transfer the energy to chlorophyll, turned to be insufficiently substantiated experimentally until recently. At the same time the discovered ability of PhBP for reversible redox transformations together with the new data on the nature of fluorescence of blue-green algae and PhBP localization in the cell allowed a suggestion that PhBP can independently of chlorophyll or together with it directly participate in photochemical reactions of photosynthesis.