title: Hydrogen atoms in proteins: positions and dynamics.
abstract: Hydrogen atoms constitute about half of the atoms in proteins. Thus they contribute to the complex energy landscape of proteins [Frauenfelder, H., Sligar, S. G. & Wolynes, P. G. (1991) Science 254, 1598-1603]. Neutron crystal structure analysis was used to study the positions and mean-square displacements of hydrogen in myoglobin. A test of the reliability of calculated hydrogen atom coordinates by a comparison with our experimental results has been carried out. The result shows that >70% of the coordinates for hydrogen atoms that have a degree of freedom is predicted worse than 0.2 A. It is shown that the mean-square displacements of the hydrogen atoms obtained from the Debye-Waller factor can be divided into three classes. A comparison with the dynamic mean-square displacements calculated from the elastic intensities obtained from incoherent neutron scattering [Doster, W., Cusack, S. & Petry, W. (1989) Nature 337, 754-756] shows that mainly the side-chain hydrogen atoms contribute to dynamic displacements on a time scale faster than 100 ps.
authors.affiliation: Physik Department E17, Technische Universität Munich, James-Franck-Strasse, 85748 Garching, Germany.
authors.forename: Niklas
authors.initials: N
authors.lastname: Engler
authors.forename: Andreas
authors.initials: A
authors.lastname: Ostermann
authors.forename: Nobuo
authors.initials: N
authors.lastname: Niimura
authors.forename: Fritz G
authors.initials: FG
authors.lastname: Parak
mesh_terms: D006859:Hydrogen / Q000737:chemistry*; D009211:Myoglobin / Q000737:chemistry*; D009502:Neutrons
chemical_list: D009211:Myoglobin; D006859:Hydrogen