title: Protein dynamics as seen by (quasi) elastic neutron scattering.
abstract: Elastic and quasielastic neutron scattering studies proved to be efficient probes of the atomic mean square displacement (MSD), a fundamental parameter for the characterization of the motion of individual atoms in proteins and its evolution with temperature and compositional environment.
  
  
  
  We present a technical overview of the different types of experimental situations and the information quasi-elastic neutron scattering approaches can make available. In particular, MSD can crucially depend on the time scale over which the averaging (building of the "mean") takes place, being defined by the instrumental resolution. Due to their high neutron scattering cross section, hydrogen atoms can be particularly sensitively observed with little interference by the other atoms in the sample. A few examples, including new data, are presented for illustration.
  
  
  
  The incoherent character of neutron scattering on hydrogen atoms restricts the information obtained to the self-correlations in the motion of individual atoms, simplifying at the same time the data analysis. On the other hand, the (often overlooked) exploration of the averaging time dependent character of MSD is crucial for unambiguous interpretation and can provide a wealth of information on micro- and nanoscale atomic motion in proteins.
  
  
  
  By properly exploiting the broad range capabilities of (quasi)elastic neutron scattering techniques to deliver time dependent characterization of atomic displacements, they offer a sensitive, direct and simple to interpret approach to exploration of the functional activity of hydrogen atoms in proteins. Partial deuteration can add most valuable selectivity by groups of hydrogen atoms. "This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo".
authors.affiliation: Department of Mathematical and Informatics Sciences, Physical Sciences and Earth Sciences, University of Messina, Viale D'Alcontres 31, 98166 Messina, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Magazù
authors.affiliation: European Spallation Source ERIC, P.O. BOX 176, 22100 Lund, Sweden; HAS Wigner Researh Center, P.O. BOX 49, 1525 Budapest, Hungary. Electronic address: ferenc.mezei@esss.se.
authors.forename: F
authors.initials: F
authors.lastname: Mezei
authors.affiliation: Institut-Laue-Langevin, BP 156, 38042 Grenoble Cedex 9, France.
authors.forename: P
authors.initials: P
authors.lastname: Falus
authors.affiliation: Institut-Laue-Langevin, BP 156, 38042 Grenoble Cedex 9, France.
authors.forename: B
authors.initials: B
authors.lastname: Farago
authors.affiliation: Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831, USA.
authors.forename: E
authors.initials: E
authors.lastname: Mamontov
authors.affiliation: Helmholtz-Zentrum-Berlin, Glienicker Str 100, 14109 Berlin, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Russina
authors.affiliation: Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale D'Alcontres 31, 98166 Messina, Italy; Institute for Integrative Biology of the Cell (I2BC), CEA-CNRS-Université Paris Sud, 91400 Orsay, France.
authors.forename: F
authors.initials: F
authors.lastname: Migliardo
mesh_terms: D004548:Elasticity; D005990:Glycerol / Q000737:chemistry; D006859:Hydrogen; D009113:Muramidase / Q000032:analysis; D009211:Myoglobin / Q000032:analysis; D033363:Neutron Diffraction / Q000379:methods*; D011506:Proteins / Q000032:analysis*; D012542:Scattering, Radiation; D013057:Spectrum Analysis; D013696:Temperature; D013997:Time Factors; D014199:Trehalose / Q000737:chemistry
chemical_list: D009211:Myoglobin; D011506:Proteins; D006859:Hydrogen; D014199:Trehalose; D009113:Muramidase; D005990:Glycerol
keywords: Elastic incoherent scattering; Lamb-Mossbauer factor; Mean Square Displacement; Neutron scattering; Resolution elastic neutron scattering