title: Protein reaction kinetics in a room-temperature glass.
abstract: Protein reaction kinetics in aqueous solution at room temperature are often simplified by the thermal averaging of conformational substates. These substates exhibit widely varying reaction rates that are usually exposed by trapping in a glass at low temperature. Here, it is shown that the solvent viscosity, rather than the low temperature, is primarily responsible for the trapping. This was demonstrated by placement of myoglobin in a glass at room temperature and subsequent observation of inhomogeneous reaction kinetics. The high solvent viscosity slowed the rate of crossing the energy barriers that separated the substates and also suppressed any change in the average protein conformation after ligand dissociation.
authors.affiliation: Laboratory of Chemical Physics, National Institutes of Health, Bethesda, MD 20892-0520, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Hagen
authors.forename: J
authors.initials: J
authors.lastname: Hofrichter
authors.forename: W A
authors.initials: WA
authors.lastname: Eaton
mesh_terms: D001665:Binding Sites; D002248:Carbon Monoxide / Q000737:chemistry* / Q000378:metabolism; D005898:Glass; D007700:Kinetics; D008024:Ligands; D009211:Myoglobin / Q000737:chemistry* / Q000378:metabolism; D010782:Photolysis; D011487:Protein Conformation; D013057:Spectrum Analysis; D013696:Temperature; D014199:Trehalose; D014783:Viscosity
chemical_list: D008024:Ligands; D009211:Myoglobin; D002248:Carbon Monoxide; D014199:Trehalose