Monday 31.01.

8:00 PST -  11:00 EST - 16:00 UTC

 17:00 CET - 18:00 IST - 0:00 CST

Felix Ritort

Small Biosystems Lab, Departament de Física de la Matèria Condensada, Facultat de Física, Universitat de Barcelona

Calorimetric force spectroscopy of nucleic acids and proteins

DNA, RNA, and proteins are polymers that fold into three-dimensional structures to perform their biological function. How these molecules fold is, however, not fully understood. Although some models advocate for funnel-like energy landscapes, others envision folding as a cooperative process mediated by the sequential formation of intermediates. In this talk, I introduce calorimetric force spectroscopy in a temperature jump optical trap as a powerful tool to understand the folding of nucleic acids and proteins. While cooperativity in nucleic acids arises from base stacking interactions in proteins, it is determined by the low configurational entropy of the transition state along the folding pathway. Here, I show how accurate measurements of heat capacity changes during the folding of protein barnase permit us to characterize the transition state's enthalpy, entropy, and heat capacity. We find that the transition state has the properties of a molten globule, i.e., high-free energy and low configurational entropy, being structurally similar to the native state.