title: Protein dynamics in supercooled water: the search for slow motional modes.
abstract: The impact of studying protein dynamics in supercooled water for identifying slow motional modes on the micros time scale is demonstrated. Backbone 15N spin relaxation parameters were measured at -13 degrees C for ubiquitin, which plays a central role for signaling proteolysis, cellular trafficking and kinase activation in eukaryotic organisms. A hitherto undetected motional mode involving Val 70 was found, which may well play an important role for ubiquitin recognition. The measurement of rotating frame 15N relaxation times as a function of the spin-lock field allowed determination of the correlation time of this motional mode, which would not have been feasible above 0 degrees C.
authors.affiliation: Department of Chemistry and Structural Biology, University at Buffalo, The State University of New York Buffalo 14260, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Mills
authors.forename: Thomas
authors.initials: T
authors.lastname: Szyperski
mesh_terms: D003080:Cold Temperature; D008958:Models, Molecular; D009587:Nitrogen Isotopes / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D017433:Protein Structure, Secondary; D013997:Time Factors; D025801:Ubiquitin / Q000737:chemistry* / Q000378:metabolism; D014867:Water / Q000737:chemistry*
chemical_list: D009587:Nitrogen Isotopes; D025801:Ubiquitin; D014867:Water