title: Enzyme activity and flexibility at very low hydration.
abstract: Recent measurements have demonstrated enzyme activity at hydrations as low as 3%. This raises the question of whether hydration-induced enzyme flexibility is important for activity. Here, to address this, picosecond dynamic neutron scattering experiments are performed on pig liver esterase powders at 0%, 3%, 12%, and 50% hydration by weight and at temperatures ranging from 120 to 300 K. At all temperatures and hydrations, significant quasielastic scattering intensity is found in the protein, indicating the presence of anharmonic, diffusive motion. As the hydration increases, a temperature-dependent dynamical transition appears and strengthens involving additional diffusive motion. The implication of these results is that, although the additional hydration-induced diffusive motion in the protein detected here may be related to increased activity, it is not required for the enzyme to function.
authors.affiliation: Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Kurkal
authors.forename: R M
authors.initials: RM
authors.lastname: Daniel
authors.forename: John L
authors.initials: JL
authors.lastname: Finney
authors.forename: M
authors.initials: M
authors.lastname: Tehei
authors.forename: R V
authors.initials: RV
authors.lastname: Dunn
authors.forename: Jeremy C
authors.initials: JC
authors.lastname: Smith
mesh_terms: D000818:Animals; D004058:Diffusion; D004548:Elasticity; D004789:Enzyme Activation; D004795:Enzyme Stability; D004950:Esterases / Q000032:analysis* / Q000737:chemistry*; D008099:Liver / Q000201:enzymology*; D009038:Motion; D012996:Solutions; D013552:Swine; D013696:Temperature; D014867:Water / Q000032:analysis / Q000737:chemistry*
chemical_list: D012996:Solutions; D014867:Water; D004950:Esterases