报告题目：Why Use Fluorescence Resonance EnergyTransfer When Pyrene Excimer Fluorescence Is Conceptually Much Simpler andWorks as Well in Many Instances?
报告人：Jean Duhamel
Department of Chemistry,University of Waterloo
报告地点：907-1445
报告时间：2016年6月21日上午9:30-10:30
Jean Duhamel obtained hisPh. D. in 1989 from the Institut National Polytechnique de Lorraine in Nancy(France) under the supervision of Dr. J.-C. André. His graduate work focused on the study oftransient effects observed in the kinetics of excimer formation in viscoussolutions. He then joined the laboratory of Prof. M. A. Winnik in 1990 at theUniversity of Toronto (Canada) where he applied pyrene excimer formation tocharacterize the behavior of macromolecules. In 1993, he moved to thelaboratory of Prof. P. Lu at the University of Pennsylvania (USA) to studyoligonucleotides by fluorescence anisotropy. After joining the University ofWaterloo (Canada) in 1996, he expanded the use of time-resolved fluorescence tothe point where it can now be applied to probe the internal dynamics of anytype of pyrene-labeled macromolecular construct in solution. He has held aTier-2 Canada Research Chair (2001-2011) and since 2011, has been the directorof the Institute for Polymer Research at Waterloo.
Abstract:
FluorescenceResonance Energy Transfer, more commonly referred to as FRET, has been appliedto characterize the behaviour of a bewildering number of macromolecules insolution or in the bulk. Peptideend-to-end cyclization, polymer diffusion in latex films, or the extent ofmacromolecular self-assembly in solution or in the bulk are typical examples ofphenomena that have all been successfully characterized by FRET. As a result,FRET is by far the best known photophysical process used to characterizemacromolecules. Nevertheless and for all its accomplishments, FRET remains atechnique plagued by a number of important drawbacks. First, quantitative analysis of FRET dataremains mathematically challenging due to the dependency of the FRET rateconstant with the sixth power of the distance separating the donorfrom the acceptor and the rearrangement over time of the distribution ofdonor-acceptor pairs. Second, theanalysis of FRET data obtained in solution with macromolecules randomly labeledwith either a FRET donor or acceptor is usually so complex that FRET is onlyapplied in such instance in a qualitative manner. Third, directenergy transfer is difficult to avoid when working at high concentration offluorescently labeled macromolecules.
Inthis lecture, I will argue that excimer formation between an excited and aground-state pyrene covalently attached onto a macromolecule avoids all thedrawbacks plaguing FRET experiments while providing relevant quantitativeinformation on the process under investigation. Examples of applicationsdescribed in this lecture will include the characterization of 1) the internaldynamics of pyrene-labeled macromolecule in solution, 2) the structure ofbiological macromolecules, 3) the diffusion of pyrene-labeled polymers in latexfilms, and 4) the level of intermolecular interactions taking place withviscosity index improvers. This broad range of applications justifies the claimthat pyrene excimer fluorescence can be used in a manner that is much moreefficient than FRET to probe macromolecules at the molecular level. More information about our work on theapplication of pyrene excimer formation to the study of macromolecules can befound in the following reviews.
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