Ultrafast energy transfer pathways in R-phycoerythrin from Polysiphonia urceolata

Abstract

Energy transfer (ET) processes between chromophores in R-phycoerythrin (R-PE) from Polysiphonia urceolata were studied by use of ultrafast spectroscopic methods. Several primary ET pathways were elaborated. A fluorescence decay component with a time constant of several hundred picoseconds observed by streak camera is tentatively assigned to the reversible formation of exciton traps between α84 and β84 pigment pairs. In order to investigate much faster ET processes in R-PE, a noncollinear optical parametric amplifier based femtosecond time-resolved transient fluorescence spectrometer was employed. The results reveal that the ET between α84 and β84 pigment pair has a time constant of 1-2 ps; the energy migration between α84 and β84 pairs within the R-PE trimer has a time constant of 30-40 ps. We also demonstrated an ET process from phycourobilin to phycoerythrobilin with a time constant as fast as 2.5-3.0 ps, which was directly observed in fluorescence kinetics by selective excitation of the phycourobilin molecules acting as the energy donor.

In silico model of an antenna of a phycobilisome and energy transfer rates determination by theoretical Förster approach

“…The same group 27 also reported an ET process in PE from PUB to PEB of 2.5-3 ps. Our results shown in Table III agree with the experimental results informed by Chen et al 28 for Phycoerythrin with ET rates from PEBa84 to PEBb84 of 1-2 ps, and a84 to b84 from the next heterodimer of 30-40 ps, they are also consistent with the experimental values obtained for Phycocyanin from Anabaena variabilis, measured by time-resolved fluorescence and anisotropy spectra. 29 These values are consistent with our results, which gave a ET rate of 2 ps, and in the trimer, our calculations also agree in time transfer rates in the vicinity of 50-100 ps.…”

“…Our results on the ET rates calculated for phycoerythrin were not comparable with other theoretical results, because only here the extended F€ orster approach was used, using the spectroscopic parameters reported by us. 25 Nevertheless, our calculations are also in the order of magnitude of those reported by Chen et al 28 The analysis presented here combines theoretical and experimental tools and provides valuable information about the possible preferential pathways considering only the phycobiliprotein components of the phycobilisome.…”

Trehalose Preserves the Integrity of Lyophilized Phycoerythrin–AntiHuman CD8 Antibody Conjugates and Enhances their Thermal Stability in Flow Cytometric Assays

“…Following photoexcitation in the PUB spectral region, the chromophore bound to the protein are involved in energy transfer processes that result in the final fluorescence emission characteristic of the R‐PE complex 26. Being energy transfer strongly dependent upon the distance and relative orientation of the chromophores, fluorescence represents a very sensitive probe of the R‐PE native conformation 25.…”

Methods of phycobiliprotein extraction from Gracilaria crassa and its applications in food colourants

“…The light used in TCSPC was nanoLEDs and excitation, emission wavelength was set as 490 nm and 578 nm, respectively (see Supplementary material Fig. 3) [28]. …”