title: The inverse relationship between protein dynamics and thermal stability.
abstract: Protein powders that are dehydrated or mixed with a glassy compound are known to have improved thermal stability. We present elastic and quasielastic neutron scattering measurements of the global dynamics of lysozyme and ribonuclease A powders. In the absence of solvation water, both protein powders exhibit largely harmonic motions on the timescale of the measurements. Upon partial hydration, quasielastic scattering indicative of relaxational processes appears at sufficiently high temperature. When the scattering spectrum are analyzed with the Kohlrausch-Williams-Watts formalism, the exponent beta decreases with increasing temperature, suggesting that multiple relaxation modes are emerging. When lysozyme was mixed with glycerol, its beta values were higher than the hydrated sample at comparable temperatures, reflecting the viscosity and stabilizing effects of glycerol.
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA. amos.tsai@nist.gov
authors.forename: A M
authors.initials: AM
authors.lastname: Tsai
authors.forename: T J
authors.initials: TJ
authors.lastname: Udovic
authors.forename: D A
authors.initials: DA
authors.lastname: Neumann
mesh_terms: D000818:Animals; D002417:Cattle; D002645:Chickens; D004795:Enzyme Stability / Q000187:drug effects / Q000528:radiation effects; D005990:Glycerol / Q000737:chemistry* / Q000494:pharmacology; D006358:Hot Temperature; D009113:Muramidase / Q000737:chemistry*; D009502:Neutrons; D011487:Protein Conformation; D011489:Protein Denaturation / Q000187:drug effects / Q000528:radiation effects; D011506:Proteins / Q000737:chemistry; D012259:Ribonuclease, Pancreatic / Q000737:chemistry*; D012542:Scattering, Radiation; D013816:Thermodynamics; D014867:Water / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D011506:Proteins; D014867:Water; D012259:Ribonuclease, Pancreatic; D009113:Muramidase; D005990:Glycerol