Associate Professor Sapun Parekh, The University of Texas at Austin, Biomedical Engineering

Revealng hierachical organization in protein networks using chemical microscopy
Structure-function relationships often define how molecular processes give rise to macroscopic observables. In this talk, I will present our recent work using nonlinear chemical microscopy and spectroscopy to reveal unique structure-function relationships in polymeric soft matter systems. We have hyperspectral Raman imaging to map protein structure in fibrin biopolymer networks that lie at the center of blood clotting disorders, showing that fibrin biopolymers change structure in a spatially heterogeneous manner when exposed to tensile loads. This is further shown by mechanical damage to protein fibers at the single fiber, and single molecule, scale. Finally, we find that fibrin structural transitions appear to form a regulatory mechanism that controls clot clearance.
In a separate project, we have been studying the protein organization of protein condensates and fibrils. Condensates, formed via spontaneous phase separation of disordered proteins, are responsible for many functions in cells, specifically stress granule formation, chromatin organization, and RNA transcription. However, aberrant molecular transitions are believed to lead to protein fibrillation and neurodegenerative disease. Quantifying the structure of proteins in these materials in situ, we have shown that protein droplets can be driven to exhibit unique protein molecular structures at droplet interfaces compared to the bulk, suggesting they are precursors to fibril formation, which themselves show unique polymorphisms and toxic behaviors.

Program:
15.00-15.15: coffee & cake in the foyer
15.15-16.15: scientific talk in Auditorium I

(16.15-17: Q&A session for PhD students and master students)