title: Light tolerance of R-phycoerythrin and a tandem conjugate observed by single molecule recrossing events.
abstract: The recrossing of single molecules in a probe volume was used to investigate light harvesting and energy transfer between R-phycoerythrin (R-PE) and a tandem conjugate dye. The normalized recrossing ratio, Nr/Nt, was defined as the number of molecules that reenter the probe volume (Nr) to the total number of molecules detected (Nt). The energy transfer process in phycobiliproteins was studied as a function of excitation irradiation and irradiation time. This was achieved by investigating the average baseline-subtracted fluorescence intensity, normalized molecular recrossing ratio (Nr/Nt), and the number of molecules detected per second. The photon saturation irradiance of the R-PE and the tandem conjugate were compared with each other, showing that energy transfer to the tandem dye significantly improves photostability and light tolerance of the phycobiliprotein. The Nr/Nt ratio was used to study the photophysical properties of R-phycoerythrin and the tandem conjugate Streptavidin R-Phycoerythrin-AlexaFluor-647 (PE-647). Normalized molecular recrossings showed that energy transfer to a tandem conjugate could reduce the formation of triplet states in R-phycoerythrin and extend the light tolerance of certain phycobiliproteins.
authors.affiliation: Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061, USA.
authors.forename: Sean M
authors.initials: SM
authors.lastname: Burrows
authors.forename: Payal
authors.initials: P
authors.lastname: Patel
authors.forename: Dimitri
authors.initials: D
authors.lastname: Pappas
mesh_terms: D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000737:chemistry; D004735:Energy Transfer; D005453:Fluorescence; D008027:Light; D010777:Photochemistry; D017785:Photons; D010799:Phycoerythrin / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry*; D010944:Plants / Q000737:chemistry*; D019809:Streptavidin / Q000737:chemistry*; D013997:Time Factors
chemical_list: D010940:Plant Proteins; D010799:Phycoerythrin; C067297:8-aminohexylamino cAMP; D019809:Streptavidin; D000242:Cyclic AMP