title: Hydrogen and deuterium in myoglobin as seen by a neutron structure determination at 1.5 A resolution.
abstract: From the first days of protein neutron structure determination sperm whale myoglobin was an object under investigation [Nature 224 (1969) 143, J. Mol. Biol. 220 (1991) 381]. Nevertheless myoglobin is still of interest [Proc. Natl. Acad. Sci. USA 97 (2000) 3872]. The feasibility of the monochromatic neutron diffractometer BIX-3 at the JRR-3M reactor at the JAERI [J. Phys. Chem. Solids 60 (1999) 1623], to collect high-resolution diffraction data in a relatively short time stimulated us to repeat the structural determination of myoglobin. The structure of metmyoglobin has been determined up to a resolution of 1.5 A. The hydrogen atoms were replaced in part, by deuterium soaking the crystals for more than 10 years in D(2)O. A refinement of all atoms has been performed including the refinement of individual mean square displacements and occupancies of the exchangeable protons in backbone hydrogen bonds. A method is described to show clear negative scattering densities of the H atoms. Water molecules within the protein and on the molecule surface are shown. The exchangeability of H atoms is correlated with structural distribution and flexibility.
authors.affiliation: Advanced Science Research Centre, JAERI, Tokai-Mura, Ibaraki 319-1195, Japan.
authors.forename: Andreas
authors.initials: A
authors.lastname: Ostermann
authors.forename: Ichiro
authors.initials: I
authors.lastname: Tanaka
authors.forename: Niklas
authors.initials: N
authors.lastname: Engler
authors.forename: Nobuo
authors.initials: N
authors.lastname: Niimura
authors.forename: Fritz G
authors.initials: FG
authors.lastname: Parak
mesh_terms: D000818:Animals; D003461:Crystallography; D003903:Deuterium / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D008786:Metmyoglobin / Q000737:chemistry / Q000378:metabolism; D009068:Movement; D009211:Myoglobin / Q000737:chemistry* / Q000378:metabolism; D009502:Neutrons; D018583:Pliability; D011487:Protein Conformation; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D014867:Water / Q000378:metabolism; D014907:Whales
chemical_list: D009211:Myoglobin; D014867:Water; D008786:Metmyoglobin; D006859:Hydrogen; D003903:Deuterium