Project Summary from the Parent Award Over the past 50 years, the field of biophysical chemistry has learned an enormous amount about the relationships between the function, dynamics and folding of soluble proteins. The next stage in biological science involves addressing more complex problems on more challenging systems using increasingly sophisticated approaches augmented by computational methods. The Sosnick lab has followed this path. We are conducting studies of membrane proteins, condensates and disordered proteins. Our ability to address these topics arises in part from our expertise in the folding of soluble and more recently, membrane proteins. We build on this experience and knowledge to advance new or improve existing methods. The proposed research relies heavily on hydrogen exchange (HX), a method developed to study folding and dynamics yet possessing broad transferability to many methods. We plan to continue this approach and study the voltage activation of a sensory motor protein, metabolite transport across a bilayer, stress-induced phase separation, and properties of disordered proteins in addition to membrane protein folding. To address these topics in depth, we are expanding HX's applicability to membrane proteins under an activating voltage, during their folding, and even in vivo to examine their dynamics in cells. These studies are augmented by simulations conducted with our Upside algorithm that is 103-104 fold faster than ordinary simulations. This speed enables Upside to produce HX patterns that can be compared to experiment. Many of the projects are collaborative, leveraging our skills and interests with those of other labs, which further supports the value of our studies.