Abstract: Through the course of her career, Françoise Winnik has been a tremendous advocate for the use of fluorescence techniques in the characterization of macromolecules in solution. Fluorescence resonance energy transfer (FRET) and pyrene excimer formation (PEF) were the cornerstones of numerous studies conducted by Françoise and she applied these techniques with high precision to understand in incredible details the behavior at the molecular level of complex macromolecules and their assemblies in solution. Her studies have been critical in establishing PEF as a robust experimental technique to probe the conformation of macromolecules in solution. This laboratory was inspired by these early studies, which probed macromolecules by harvesting the ability of PEF to respond to the local concentration of pyrene labels in a qualitative manner. Interpretation of these earlier results led to the development of a blob-based methodology aiming at quantitatively describing the internal density of macromolecules labeled with pyrene. This presentation will illustrate how this blob-based approach can be applied to probe the conformation of complex macromolecules such as polymeric bottle brushes (PBBs) and polypeptides in solution, by defining a blob as the volume probed by an excited pyrene covalently attached to a macromolecule. The application of blob-based approaches to the study of PBBs yielded their persistence length and in the case of polypeptides, they have led to the first direct 1:1 correspondence between experimental and predicted protein folding times ever reported in the scientific literature. With these new developments, PEF is entering a realm for the characterization of macromolecules, that used to be the sole preserve of scattering techniques. Françoise would have been most pleased to learn about these new developments in the application of PEF, a technique which she contributed so much to promote.

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