R-phycoerythrin Research Articles

Enhanced recovery of R-phycoerythrin using recombination cell-assisted pressurized fluid extraction: yield, characterization, and antioxidant evaluation

The recovery of phycobiliproteins, with an emphasis on R-phycoerythrin (R-PE), from Solieria filiformis macroalgae was investigated in the current study. This is accomplished using an environmentally friendly method known as pressurized fluid extraction. Phycobiliprotein production was analyzed over time, considering four different parameters: i) solvents (ultrapure water and phosphate buffer), ii) macroalgae particle sizes, iii) stirring, and iv) pressure of 200 to 800 bar. Notably, the highest R-PE yield reached an impressive 22.53 mg/g dry biomass. The best extraction conditions were identified as a macerated structure, employing a combination of 500 bar pressure and agitation facilitated by a recombination cell. R-phycocyanin (R-PC) was also extracted with a 3.70 mg/g yield. Two distinct extracts, crude and precipitate, underwent comprehensive characterization. Extracted R-PE exhibited an α-helix structure (80.51–90.39 %), suggesting the existence of other proteins in both extracts. Three different subunits, α (15 kDa), β (21 kDa), and γ (29 kDa), were segregated under SDS-PAGE. Moreover, both extracts demonstrated antioxidant capacity, achieving a 99.55 % reduction in 2,2-diphenyl-1-picryl-hydrazil (DPPH) radicals and a 13.94 % chelation of ferrous ions. This study reports the extraction of biomolecules using the recombination cell for the first time in the literature, proving an appealing alternative for non-aggressive extraction with inherent biological activity. These findings underscore the potential applications of these extracted phycobiliproteins in various fields, including biotechnology and health.

Stability of R-phycoerythrin from Furcellaria lumbricalis – Dependence on purification strategies and purity

R-phycoerythrin (R-PE) is the most abundant, naturally occurring phycobiliproteins found in red algae. The spectroscopic and structural properties of phycobiliproteins exhibit unique absorption characteristics with two significant absorption maxima at 498 and 565 nm, indicating two different chromophores of R-PE, phycourobilin and phycoerythrobilin respectively. This study aimed to clarify how the stability of R-PE purified from F. lumbricalis was affected by different purification strategies. Crude extracts were compared to R-PE purified by i) microfiltration, ii) ultrafiltration, and iii) multi-step ammonium sulphate precipitation followed by dialysis. The stability of the different R-PE preparations was evaluated with respect to pH (2, 4, 6, 7, 8, 10 and 12) and temperature (20, 40, 60, 80 and 100 °C). The absorbance spectra indicated higher stability of phycourobilin as compared to phycoerythrobilin for heat and pH stability in the samples. All preparations of R-PE showed heat stability till 40 °C from the findings of color, concentration of R-PE and fluorescence emission. The crude extract showed stability from pH 6 to 8, whereas R-PE purified by ultrafiltration and multi-step ammonium sulphate precipitation were both stable from pH 4 to 8 and R-PE purified by microfiltration exhibited stability from pH 4 to 10 from the results of color, SDS-PAGE, and concentration of R-PE. At pH 2, the color changed to violet whereas a yellow color was observed at pH 12 in the samples along with the precipitation of the protein.

Probing the potential of mercury removal by covalently immobilized phycobiliproteins onto the surface of chitosan beads

Mercury emissions represent a significant risk to the environment and human health. Mercury is persistent and can circulate in the environment for thousands of years, which is why treating this toxic metal is important. Chitosan polymer is easily obtainable, and it has good mercury adsorption characteristics. This study aimed to improve its capabilities to absorb mercury by immobilizing phycobiliproteins (PBPs) onto the surface of chitosan beads (chitosan–PBPs). Phycobiliproteins, light-harvesting proteins from algae and cyanobacteria, have several industrially essential applications. These proteins can bind heavy metals with high affinities. Protein extracts obtained from both Arthrospira platensis, with C-phycocyanin (C-PC) as the primary protein, and Porphyra yezoensis, with R-phycocyanin (R-PC) and R-phycoerythrin (R-PE) as the dominant PBPs, were covalently immobilized onto chitosan beads. Beads with immobilized PBPs were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. Binding analysis showed that, on average, each chitosan bead weighed 20 mg and immobilized 63.54 μg of PBPs from Spirulina and 44.12 μg of PBPs from Porphyra. Immobilized proteins were still in their native state, with no visible color change months after immobilization. Chitosan–PBPs and chitosan alone were tested for mercury adsorption at pH 4 and pH 7 by atomic absorption spectroscopy. The tested concentration range of mercury was from 1 to 70 ppm. Affinity, calculated using Henry's binding isotherm, of chitosan–PBPs for mercury was twice as much higher at both pH values than chitosan alone. Furthermore, chitosan-PBP beads were able to absorb more mercury than chitosan alone. These results showed that the covalent immobilization of PBPs onto chitosan improves its mercury adsorption characteristics and creates a more efficient eco-friendly adsorbent to potentially remove mercury ions in the tested concentration range from polluted waters.

Extraction and characterization of R-phycoerythrin from wet and lyophilized macroalgae Solieria filiformis by pressurized water method

The present study evaluated the production of R-phycoerythrin (R-PE) extracted from the macroalgae Solieria filiformis through a green technology (pressurized water method). The extraction process over time and the macroalgae structure were analyzed. Two samples (freeze-dried and wet biomass, with 1 % and 10 % m/v, respectively) were studied at pressures up to 500 bar. R-PE maximum yield was reached for lyophilized seaweed structure after 360 min, obtaining 0.67 mg of R-PE per gram of dry biomass. In contrast, wet biomass reached 0.05 mg of R-PE per gram of wet biomass. Crude and precipitated extracts were characterized using the following techniques: electrophoresis, circular dichroism, and FTIR. The carbohydrate content was also determined. The biomolecule showed R-PE characteristic spectra, fluorescence, and α-helix structure as the main element of its secondary structure (93.28–95.24 %), indicating the presence of other proteins in the precipitated extract. Precipitated extract's cytotoxic activity was assessed through an MTT assay against tumor cell lines of colorectal cancer (HCT116), prostate cancer (PC3), glioblastoma cancer (SNB-19), and HL60 (promyeloblast leukemia). The most prominent in vitro results were in HL-60 and HCT-116 cell lines.

Reliable quality of R-phycoerythrin derived from Portieria hornemannii for effective antioxidant, antibacterial, and anticancer activity

The phycobiliprotein is a light-harvesting fluorescent probe; Phycoerythrin is a pigment used in many industrial, and pharmaceutical applications; including fluorescence resonance energy transfer and flow cytometry. The main objective of the current study was purifying the phycoerythrin in Portieria hornemannii. The phycoerythrin pigment was dialyzed commonly using Q sepharose, but it is high cost. However, the alternative method is DEAE-Sephadex is cost-effective, high- yield, pure compound, and has high activity performance. Then the R-Phycoerythrin (R-PE) compound was extracted in 0.02 M of phosphate buffer (pH–7.2). R-PE investigated the FT-IR, HPLC, SDS-PAGE and including physico-chemical properties. Then the purified R-PE compound was evaluated by an antibacterial, antioxidant, and anticancer activity. The R-Phycoerythrin was showing a maximum inhibition effect of high concentration (IC50value 77.98 µg/ml) against the colon cancer HT-29 cell line.

Antioxidant and Anti-tyrosinase Activities of Halymenia durvillei Water Extract Containing R-Phycoerythrin Before and After Microencapsulation

Halymenia durvillei water extract (HDWE) contains a dark-pink colored pigment of Rphycoerythrin (R-PE), which its stability is influenced by temperature and pH andpossesses biological activities. Microencapsulation could be the solution to preservingthe nature of R-PE. This study characterized the HDWE emulsion and analyzed the RPE content, antioxidants, and anti-tyrosinase activities before and after microencapsulation using sodium caseinate and maltodextrin (M-HDWE). Halymenia durvillei was extracted in distilled water (ratio 1:2, w/v) for 24 hours at 4 °C. Sodium caseinate to maltodextrin coating ratios were 1:2; 1:4; 1:6 and 1:12. Emulsion (viscosity, color, and R-PE content) and powder characteristics (surface morphology) were determined using Brookfield DV2T, ColorFlex EZ Hunterlab, UV-VIS spectrophotometry, and JeolSEM, respectively. The antioxidant and anti-tyrosinase activities were determined using the Ferric Reducing Antioxidant Power (FRAP) and mushroom tyrosinase assays. The Commision Internationale d’Éclairage (CIE) L* a* b* colorimetry result showed that the more maltodextrin and the lower viscosity, the more intense the emulsion color. Despite HDWE having roughly six-fold more R-PE content, all M-HDWE treatment samples exhibited equal R-PE contents (p 0.05). The M-HDWE 1:2; 1:4; 1:6; and 1:12 microcapsules had more wrinkled spheres and fewer cracks than MHDWE 0. The M-HDWE 1:2 had 33.10% lower antioxidant activity than the HDWE and was the highest compared to other M-HDWE compositions (17.15±1.27 µM/µg extract, p 0.05). Meanwhile, all M-HDWE had low anti-tyrosinase activity. It can be concluded that microencapsulation could be a solution for preserving HDWE’s antioxidant activity but not its anti-tyrosinase activity

Antioxidant and Anti-tyrosinase Activities of Halymenia durvillei Water Extract Containing R-Phycoerythrin Before and After Microencapsulation

Halymenia durvillei water extract (HDWE) contains a dark-pink colored pigment of Rphycoerythrin (R-PE), which its stability is influenced by temperature and pH and possesses biological activities. Microencapsulation could be the solution to preserving the nature of R-PE. This study characterized the HDWE emulsion and analyzed the RPE content, antioxidants, and anti-tyrosinase activities before and after microencapsulation using sodium caseinate and maltodextrin (M-HDWE). Halymenia durvillei was extracted in distilled water (ratio 1:2, w/v) for 24 hours at 4 °C. Sodium caseinate to maltodextrin coating ratios were 1:2; 1:4; 1:6 and 1:12. Emulsion (viscosity, color, and R-PE content) and powder characteristics (surface morphology) were determined using Brookfield DV2T, ColorFlex EZ Hunterlab, UV-VIS spectrophotometry, and JeolSEM, respectively. The antioxidant and anti-tyrosinase activities were determined using the Ferric Reducing Antioxidant Power (FRAP) and mushroom tyrosinase assays. The Commision Internationale d’Éclairage (CIE) L* a* b* colorimetry result showed that the more maltodextrin and the lower viscosity, the more intense the emulsion color. Despite HDWE having roughly six-fold more R-PE content, all M-HDWE treatment samples exhibited equal R-PE contents (p 0.05). The M-HDWE 1:2; 1:4; 1:6; and 1:12 microcapsules had more wrinkled spheres and fewer cracks than MHDWE 0. The M-HDWE 1:2 had 33.10% lower antioxidant activity than the HDWE and was the highest compared to other M-HDWE compositions (17.15±1.27 µM/µg extract, p 0.05). Meanwhile, all M-HDWE had low anti-tyrosinase activity. It can be concluded that microencapsulation could be a solution for preserving HDWE’s antioxidant activity but not its anti-tyrosinase activity

Stability and Antioxidant Activity of R-Phycoerythrin from Gracilaria birdiae

ABSTRACT R-phycoerythrin (R-PE) is a red pigment present in algae with potential application in the biotechnology industry. This study aims the physical-chemical characterization and antioxidant activity of R-phycoerythrin from Gracilaria birdiae (CE-Gb). The spectroscopic stability of the pigment against different additives was also evaluated. The results showed antioxidant activity dependent on pigment concentration. Furthermore, the degradation of R-PE was maximum in CE-Gb without preservatives, and the addition of ascorbic acid (AA) reduced the color loss of the pigment during storage. G. birdiae proved to be a potential source of R-PE, which can be used as a dye in the food industry.

Optimization of R-Phycoerythrin Extraction by Ultrasound-Assisted Enzymatic Hydrolysis: A Comprehensive Study on the Wet Seaweed Grateloupia turuturu

Enzyme-assisted extraction (EAE) and ultrasound-assisted extraction (UAE) are both recognized as sustainable processes, but little has been done on the combined process known as ultrasound-assisted enzymatic hydrolysis (UAEH), and even less on seaweed. The present study aimed to optimize the UAEH of the red seaweed Grateloupia turuturu for the extraction of R-phycoerythrin (R-PE) directly from the wet biomass by applying a response surface methodology based on a central composite design. Three parameters were studied: the power of ultrasound, the temperature and the flow rate in the experimental system. Data analysis demonstrated that only the temperature had a significant and negative effect on the R-PE extraction yield. Under the optimized conditions, the R-PE kinetic yield reached a plateau between 90 and 210 min, with a yield of 4.28 ± 0.09 mg·g-1 dry weight (dw) at 180 min, corresponding to a yield 2.3 times higher than with the conventional phosphate buffer extraction on freeze-dried G. turuturu. Furthermore, the increased release of R-PE, carbohydrates, carbon and nitrogen can be associated with the degradation of G. turuturu constitutive polysaccharides, as their average molecular weights had been divided by 2.2 in 210 min. Our results thus demonstrated that an optimized UAEH is an efficient method to extract R-PE from wet G. turuturu without the need for expensive pre-treatment steps found in the conventional extraction. UAEH represents a promising and sustainable approach that should be investigated on biomasses where the recovery of added-value compounds needs to be improved.

Electric field gradient focusing with electro-osmotic flow to reduce analyte dispersion: Concept and numerical investigation

In proteomics, the need to precisely examine the protein compounds of small samples, requires sensitive analytical methods which can separate and enrich compounds with high precision. Current techniques require a minimal analysis time to obtain satisfactory compound separation where longer analysis time means better separation of compounds. But, molecular diffusion will create broadening of the separated compound bands over time, increasing the peak width, and thus reducing the resolution and the enrichment.Electric field gradient focusing (EFGF) is a separation technique, in which proteins are simultaneously separated and enriched by balancing a gradient electrostatic force with a constant hydrodynamic drag force. Because of this balance, analytes are continuously pushed back to their focusing point, limiting the time-dependent peak broadening due to molecular diffusion. Current EFGF techniques are however still suffering from peak broadening because of flow-profile inhomogeneities.In this paper, we propose to use AC electro-osmotic flow (AC EOF) to create a homogeneous flow in EFGF. The interference between the electric field gradient and the AC EOF was thoroughly analysed and the concept was validated using numerical simulations. The results show that a plug flow is obtained on top of a small, distorted boundary layer. While applying different DC electric fields in the electrolyte, a constant flow velocity can be obtained by including a DC offset to the electrodes generating the AC EOF. The plug flow is then maintained over the whole separation channel length, while an electric field gradient is applied. This way, the flow-induced contribution to peak broadening can be minimized in EFGF devices. By modelling the separation of green fluorescent protein (GFP) and R-Phycoerythrin (R-PE), it was shown that the peak width of separated compounds can be reduced and that the separation resolution can be improved, compared to current EFGF methods.

Sequential extraction process and physicochemical characterization of R-phycoerythrin and agar from red macroalgae Gracilaria birdiae

This study evaluated the sequential extraction of R-phycoerythrin (R-PE) and agar from the red macroalgae Gracilaria birdiae and the effects on yield, recovery, purity index and physicochemical characterization of both biomolecules. Three R-PE extraction and partial purification strategies were evaluated and the three most promising pigmented fractions were F25/35, F35/45 and F25/45 with purity/yield indexes 1.64/0.17, 0.71/0.44 and 0.56/ 1.20 mg.g−1 dw, respectively. In addition to the purity index, yield and recovery, optimizations 1 and 2 resulted in obtaining pigments with high intensity of red color, confirmed by the values of parameter a*: 78.30 ± 0.01, 64.07 ± 0.03 and 60.96 ± 0.02, for fractions 25/35, 35/45 and 25/45, in that order. The agar obtained from the residue of the extraction of R-PE (ARES-Gb) showed a yield of 31.64 %, higher than those reported in the literature when extracted from integral wet or dry macroalgae. In addition, RES-Gb had physicochemical and rheological properties similar to commercial agar. Therefore, the development of the biotechnological process proposed contributes to the maximum use of G. birdiae, to the valorization of this renewable source and to the blue economy.

Study of fluorescence spectroscopy and molecular mechanisms for the interaction of Hg2+ ions and R-phycoerythrin from marine algae (Porphyra yezoensis).

Heavy metal is a worldwide hazardous material, and many efforts were made to detect them sensitively and selectively. R-phycoerythrin (R-PE), a marine fluorescent protein, is abundant in red algae and participates in photosynthesis. In this work, the fluorescence spectroscopy and molecular mechanism of Hg2+ ions and R-PE were further explored through fluorescence spectrum measurements, time-resolved fluorescence lifetimes, peak fitting of Fourier transform infrared spectroscopy, and molecular docking simulation in this study. It was proved by fluorescent spectrum measurements that Hg2+ ions could lead to static fluorescence quenching. Besides, the interaction was a spontaneous and exothermic process driven by hydrogen bond and Van der Waals (VDW) force. Importantly, Hg2+ ions bound to 78LYS and 82CYS on the α chain and 73CYS and 82CYS on the β chain, which resulted in the structural changes of the peptide chain and affected the secondary structure contents of R-PE. This study further explained the effect of Hg2+ ions on marine fluorescent protein R-PE.

Combined extraction methodology for simultaneous recovery of phycobiliproteins and agar from the red alga Gracilaria chilensis C. J. Bird, McLachlan & E. C. Oliveira

The red alga Gracilaria chilensis C. J. Bird, McLachlan & E. C. Oliveira ( Agarophyton chilense Gurgel, J.N. Norris & Fredericq) is one of the few algae commercially farmed in Chile, where this alga is commonly named “Pelillo”. G. chilensis main by-product is agar, a gelling agent used in the food and pharmaceutical industries. This alga is also a valuable feedstock for the biorefinery of phycobiliproteins (PBPs), colored and fluorescent water-soluble proteins with industrial applications. This work aimed to valorize G. chilensis by sequentially extracting PBPs and agar. After freeze-thaw treatment, we successfully extracted two PBPs from alga: R-phycoerythrin (R-PE) and R-phycocyanin (R-PC). After two purification steps, we recovered 45 % of both PBPs (R-PE = 0.20 mg g −1 DW and R-PC = 0.23 mg·g −1 DW). After PBPs extraction, we successfully recovered agar from the residual algal matter. There were no significant differences between the physical parameters of agars obtained after PBP extraction and those from agars directly extracted from G. chilensis (melting and gelling temperature, and agar deformation). The agar yield after PBPs extraction was 24.9 ± 1.0 % and showed a gel strength of 726 ± 182.9 g·cm −2 , whereas agar directly extracted from alga yielded 23.1 ± 2.0 % with a gel strength of 730.5 ± 96.9 g·cm −2 . The agar obtained after PBPs extraction showed no inhibitory effects on microbial growth and allowed the effective separation of nucleic acids without agarose purification. Thereby, the method proposed in this work allowed the simultaneous extraction of PBPs and agar from G. chilensis . • The red seaweed Gracilaria chilensis ( Agarophyton chilense ) is a good source of phycobiliproteins and agar. • Phycobiliproteins are purified by salting-out and anion-exchange chromatography. • Purified phycobiliproteins (R-PE and R-PC) may be used in the food industry. • High-quality agar was successfully recovered from the residual algal matter after phycobiliproteins' extraction. • Agar extracted after phycobiliproteins' purification was useful for microbial growth and nucleic acid separation.

Highly Efficient Water-Based Extraction of Biliprotein R-Phycoerythrin From Marine the Red-Macroalga Sarcopeltis skottsbergii by Ultrasound and High-Pressure Homogenization Methods

Sarcopeltis skottsbergii is an endemic species of the southern region of South America, with R-phycoerythrin (R-PE) as an accessory photosynthetic pigment. The production of S. skottsbergii is around twenty thousand tons of dry alga per year. The evaluation of (R-PE) in a biorefinery model is still incipient in the algal biotechnology area and will be used in the food, pharmaceutical, cosmeceutical, and nutraceutical industries. This work evaluated the cell disruption and separation processes by using two green technologies, ultrasound-assisted extraction (UAE) and high-pressure homogenization (HPH), to obtain an R-phycoerythrin enriched extract from S. skottsbergii. Two-levels three-factor central composite design (CCD) and response surface methodology (RSM) were carried out to optimize the extraction conditions, including the factors for UAE (time, amplitude, and solvent) and HPH (Pressure, number of passes, and solvent). Additionally, a second-order polynomial fit was performed to fit the experimental data by the green method. HPH method was the most efficient extraction method under the conditions obtained of 100-400 MPa pressure power, 2-3 number of passes, and distilled water as solvent. Furthermore, the experimental extraction yields ranged from 4.4-5.7 mg of PE g-1 of dry biomass under the optimal extraction conditions (400 MPa; 2 passes), which agreed with the predictive yield of 4.6-5.5 mg g-1 DW. The ultrafiltration membrane used for the separation process for both methods exhibited a rejection of R-phycoerythrin concentrated at 30 KDa. Furthermore, R-phycoerythrin showed a positive correlation between the antioxidant capacity (ORAC) in the best-selected extractions. After the extraction, the same pattern was observed in Chlorophyll a and total carotenoids with DPPH. Thus, it was an attractive non-aggressive extraction alternative with biological activity of interest for formulating biotechnological products for the food industry is suggested.

Uncovering the Use of Fucoxanthin and Phycobiliproteins into Solid Matrices to Increase Their Emission Quantum Yield and Photostability

In the search for a better and brighter future, the use of natural luminescent renewable materials as substitutes for synthetic ones in the energy field is of prime importance. The incorporation of natural pigments (e.g., xanthophylls and phycobiliproteins) is a fundamental step in a broad spectrum of applications that are presently marred by their limited stability. The incorporation of bio-based luminescent molecules into solid matrices allows the fabrication of thin films, which may dramatically increase the range of applications, including sustainable photovoltaic systems, such as luminescent solar concentrators or downshifting layers. In this work, we incorporated R-phycoerythrin (R-PE), C-phycocyanin (C-PC), and fucoxanthin (FX) into poly(vinyl alcohol) (PVA) and studied their optical properties. It was found that the emission and excitation spectra of the phycobiliproteins and FX were not modified by incorporation into the PVA matrix. Moreover, in the case of FX, the emission quantum yield (η) values also remained unaltered after incorporation, showing the suitability of the PVA as a host matrix. A preliminary photostability study was performed by exposing the solid samples to continuous AM1.5G solar radiation, which evidenced the potential of these materials for future photovoltaics.

Three-phase partitioning, a recyclable method for the purification of R-phycoerythrin from a red algae Porphyra yezoensis

In this study, R-phycoerythrin (R-PE) was isolated and characterized from Porphyra yezoensis by three-phase partitioning (TPP) method. The effects of temperature, time, pH, salt saturation, and volume ratio on the purity and recovery rate of R-PE were studied. The optimum extraction conditions were determined as follows: salt saturation of 70%, temperature of 25 °C, time of 45 min, pH of 7.0, and volume ratio of 1:1. Under the optimal extraction conditions, the purity of R-PE was 3.90. The results of SDS-PAGE showed that R-PE has three bands at 23 kDa, 22 kDa, and 18 kDa, corresponding to its α, β, γ subunits. The structure and optical activity of R-PE did not change before and after purification based on ultraviolet, infrared, and fluorescence spectra. In addition, the purity and recovery rate of R-PE extracted by tert-butanol were evaluated. The results showed that the extraction performance of tert-butanol for R-PE remained unchanged in three recoveries. These show that TPP is an efficient, green, and recyclable extraction technology.

Probing the stability of the food colourant R-phycoerythrin from dried Nori flakes

This study aimed to characterise the stability of R-phycoerythrin (R-PE), a vivid natural colourant with emerging potential for application in the food industry. High-quality (A560/A280 ≥ 5), native (α-helix content 75%) R-PE was purified from commercial dried Nori (Porphyra sp.) flakes. Thermal unfolding revealed two transitions (at 56 and 72 °C), ascribed to different protein subunits. Contrary to elevated temperature, high-pressure (HP) treatment showed significant advantages: The R-PE unfolding was partly reversible and the colour bleaching was minimal. Binding of Cu2+ (6.3 × 105 M−1) and Zn2+ (1.7 × 103 M−1) influenced conformational changes in the protein tetrapyrrole chromophore without affecting R-PE structure and stability (colour). The results give new insights into the stability of R-PE suggesting its usefulness for the replacement of toxic synthetic dyes. Preservation of the red colour of R-PE could be considered in fortified food and beverages by HP processing. R-PE may act as a biosensor for Cu2+ in aquatic systems.

Single-step purified R-phycoerythrin transmits cellular imaging functionalities in vitro

A single-step and rapid chromatographic method-based purification of Gracilaria corticata (J. Agardh) R-phycoerythrin (R-PE) was attained using polyacrylamide gel electrophoresis (PAGE) technique without affecting structural integrity. The purified R-PE had a characteristic UV–Vis spectrum with three absorbance maxima at 496, 535, and 565 nm, and fluorescence at 575 nm. R-PE was obtained with a purity index of 4.2 and a recovery yield of 44.3%. SDS-PAGE analysis exhibited three sub-units i.e., 18, 21, and 31 kDa, which corresponds to α, β, and γ, respectively. This report's purification process was considered less time-consuming and could be efficiently applied to purify phycobiliproteins. The purified R-PE showed optimal stability up to 6 h at pH 7.0 when exposed to light (3000 lx), while the temperature at which the maximum stability was retained was at 20 °C. The cellular imaging property of R-PE was effectively implemented to evaluate its credentials without affecting the cell proliferation of Vero and Hep-2 cell lines with the higher IC50 concentrations in vitro. Under fluorescence microscopy and flow cytometry analysis, purified R-PE displayed the characteristic affinity towards cell imaging functions in preliminary in vitro studies.

A biohybrid strategy for enabling photoredox catalysis with low-energy light

<h2>Summary</h2> Natural systems drive the high-energy reactions of photosynthesis with efficient and broadband energy capture. Transition-metal photocatalysts similarly convert light into chemical reactivity, and yet suffer from light-limited operation and require blue-to-UV excitation. In photosynthesis, both light capture and reactivity have been optimized by separation into distinct sites. Inspired by this modular architecture, we synthesized a biohybrid photocatalyst by covalent attachment of the photosynthetic light-harvesting protein R-phycoerythrin (RPE) to the transition-metal photocatalyst tris(2,2′-bipyridine)ruthenium(II) ([Ru(bpy)₃]²⁺). Spectroscopic investigation found that absorbed photoenergy was efficiently funneled from RPE to [Ru(bpy)₃]²⁺. The utility of the biohybrid photocatalyst was demonstrated via an increase in yields for a thiol-ene coupling reaction and a cysteinyl-desulfurization reaction, including recovered reactivity at red wavelengths where [Ru(bpy)₃]²⁺ alone does not absorb.

R-Phycoerythrin from Colaconema formosanum (Rhodophyta), an Anti-Allergic and Collagen Promoting Material for Cosmeceuticals

R-phycoerythrin (R-PE), a pigment complex found in red algae, was extracted and purified from a newly identified red alga, Colaconema formosanum, and its bioactivities were examined. It was revealed that R-PE treatment resulted in high cell viability (&gt;70%) to the mammalian cell lines NIH-3T3, RBL-2H3, RAW264.7, and Hs68, and had no effect on cell morphology in NIH-3T3 cells. Its suppression effect was insignificant on the production of IL-6 and TNF-α in lipopolysaccharides-stimulated RAW264.7 cells. However, calcium ionophore A23187-induced β-hexosaminidase release was effectively inhibited in a dose-dependent manner in RBL-2H3 cells. Additionally, it was revealed to be non-irritating to bionic epidermal tissues. Notably, procollagen production was promoted in Hs68 cells. Overall, the data revealed that R-PE purified from C. formosanum exhibits anti-allergic and anti-aging bioactivities with no observed consequential toxicity on multiple mammalian cell lines as well as epidermal tissues, suggesting that this macromolecule is a novel material for potential cosmetic use.