title: Reaching the protein folding speed limit with large, sub-microsecond pressure jumps.
abstract: Biomolecules are highly pressure-sensitive, but their dynamics upon return to ambient pressure are often too fast to observe with existing approaches. We describe a sample-efficient method capable of large and very fast pressure drops (<1 nanomole, >2,500 atmospheres and <0.7 microseconds). We validated the method by fluorescence-detected refolding of a genetically engineered lambda repressor mutant from its pressure-denatured state. We resolved barrierless structure formation upon return to ambient pressure; we observed a 2.1 +/- 0.7 microsecond refolding time, which is very close to the 'speed limit' for proteins and much faster than the corresponding temperature-jump refolding of the same protein. The ability to experimentally perform a large and very fast pressure drop opens up a new region of the biomolecular energy landscape for atomic-level simulation.
authors.affiliation: Department of Physics, University of Illinois, Urbana, Illinois, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Dumont
authors.forename: Tryggvi
authors.initials: T
authors.lastname: Emilsson
authors.forename: Martin
authors.initials: M
authors.lastname: Gruebele
mesh_terms: D055592:Biophysical Phenomena; D001703:Biophysics / Q000295:instrumentation / Q000379:methods*; D008904:Miniaturization; D011312:Pressure; D011489:Protein Denaturation; D017510:Protein Folding; D012097:Repressor Proteins / Q000737:chemistry; D013816:Thermodynamics; D013997:Time Factors; D054334:Viral Regulatory and Accessory Proteins / Q000737:chemistry
chemical_list: D012097:Repressor Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins