Optical Sciences

Biomolecules and nanostructures

The Optical Sciences group studies the interaction of light and matter at the nanoscale. We do this by exploring ways to shape light and its environment. It's what we call active and passive control. Our current focus is on the interaction of light with biomolecules and nanostructures. We are part of Twente University's Department of Science and Technology and member of the MESA+ institute.
We participate in the EU-COST actions MP1102: Coherent Raman microscopy (MicroCor) and CM1202: Supramolecular photocatalytic water splitting (PERSPECT-H2O)

 

The nature of fluorescence emission in the red fluorescent protein DsRed, revealed by single-molecule detection

(full pdf)

Garcia-Parajo MF, Koopman M, van Dijk EMHP, Subramaniam V, van Hulst NF
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA (PNAS)
vol 98 issue 25: p14392-p14397 DEC 4 2001

Recent studies o­n the newly cloned red fluorescence protein DsRed from the Discosoma genus have shown its tremendous advantages: bright red fluorescence and high resistance against photobleaching. However, it has also become clear that the protein forms closely packed tetramers, and there is indication for incomplete protein maturation with unknown proportion of immature green species. We have applied single-molecule methodology to elucidate the nature of the fluorescence emission in the DsRed. Real-time fluorescence trajectories have been acquired with polarization sensitive detection. Our results indicate that energy transfer between identical monomers occurs efficiently with red emission arising equally likely from any of the chromophoric units. Photodissociation of o­ne of the chromophores weakly quenches the emission of adjacent o­nes. Dual color excitation (at 488 and 568 nm) single-molecule microscopy has been performed to reveal the number and distribution of red vs. green species within each tetramer. We find that 86% of the DsRed contain at least o­ne green species with a red-to-green ratio of 1.2-1.5. o­n the basis of our findings, oligomer suppression would not o­nly be advantageous for protein fusion but will also increase the fluorescence emission of individual monomers.
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