Speaker
Description
Many studies of biological systems are conducted in simple and dilute conditions, with macromolecular concentrations below 10 g/L—far lower than those typically found in living media. The extracellular matrix (ECM), for example, which forms the structural framework of tissues and organs, is a highly dense and complex environment. More precisely, the ECM provides a crowded and confining nanoporous environment for many biochemical processes, including enzymatic remodeling reactions, which profoundly influences their properties. Diffusion, for instance, is expected to be hindered by an increase in viscosity and, more generally, nontrivially affected by weak specific interactions, while the kinetics and steady states of biochemical reactions can be modulated in ways that are often difficult to predict.
The X-CROWD project, a 4-year ANR-funded initiative, investigates how macromolecular crowding impacts enzymatic activity within the ECM. Being direct experimental and theoretical characterization of such complex environments challenging, X-CROWD employs controlled polymer solutions to mimic varying crowding conditions, from dilute to concentrated regimes. Dextran, a branched polysaccharide, serves as a model crowder.
Rheological and self-diffusion experiments reveal that polymer solutions in dilute and semi-dilute conditions exhibit scaling-invariant properties governed by polymer topology and degree of polymerization. With the aid of molecular dynamics simulations, a connection with Rosenfeld’s excess entropy scaling hypothesis is attempted. Finally, insights from the characterization of dextran solutions are applied to understand the impact of dextran-induced crowding on enzymatic reactions, analyzed through fluorometric assays.
| Role | Master/PhD student |
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