Hydrogen atoms in proteins: positions and dynamics.
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.
Engler
Niklas
N
Physik Department E17, Technische Universität Munich, James-Franck-Strasse, 85748 Garching, Germany.
Ostermann
Andreas
A
Niimura
Nobuo
N
Parak
Fritz G
FG
D006859:Hydrogen / Q000737:chemistry*; D009211:Myoglobin / Q000737:chemistry*; D009502:Neutrons
D009211:Myoglobin; D006859:Hydrogen