Light tolerance of r-phycoerythrin and a tandem conjugate observed by single molecule recrossing events

Sean M. Burrows, Payal Patel, Dimitri Pappas

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


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-Phycocrythrin-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.

Original languageEnglish
Pages (from-to)709-715
Number of pages7
JournalApplied Spectroscopy
Issue number6
StatePublished - Jun 2009


  • Light harvesting
  • Molecular recrossing
  • R-phycoerythrin
  • Single molecule spectroscopy


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