title: Macromolecular structure phasing by neutron anomalous diffraction.
abstract: In this report we show for the first time that neutron anomalous dispersion can be used in a practical manner to determine experimental phases of a protein crystal structure, providing a new tool for structural biologists. The approach is demonstrated through the use of a state-of-the-art monochromatic neutron diffractometer at the Institut Laue-Langevin (ILL) in combination with crystals of perdeuterated protein that minimise the level of hydrogen incoherent scattering and enhance the visibility of the anomalous signal. The protein used was rubredoxin in which cadmium replaced the iron at the iron-sulphur site. While this study was carried out using a steady-state neutron beam source, the results will be of major interest for capabilities at existing and emerging spallation neutron sources where time-of-flight instruments provide inherent energy discrimination. In particular this capability may be expected to offer unique opportunities to a rapidly developing structural biology community where there is increasing interest in the identification of protonation states, protein/water interactions and protein-ligand interactions - all of which are of central importance to a wide range of fundamental and applied areas in the biosciences.
authors: Faculty of Natural Sciences, Keele University, Staffordshire, ST5 5BG, United Kingdom.|ILL, 71 avenue des Martyrs, 38000 Grenoble, France.
authors: Maxime G
authors: MG
authors: Cuypers
authors: ILL, 71 avenue des Martyrs, 38000 Grenoble, France.
authors: Sax A
authors: SA
authors: Mason
authors: Faculty of Natural Sciences, Keele University, Staffordshire, ST5 5BG, United Kingdom.|ILL, 71 avenue des Martyrs, 38000 Grenoble, France.
authors: Estelle
authors: E
authors: Mossou
authors: ILL, 71 avenue des Martyrs, 38000 Grenoble, France.
authors: Michael
authors: M
authors: Haertlein
authors: Faculty of Natural Sciences, Keele University, Staffordshire, ST5 5BG, United Kingdom.|ILL, 71 avenue des Martyrs, 38000 Grenoble, France.
authors: V Trevor
authors: VT
authors: Forsyth
authors: Faculty of Natural Sciences, Keele University, Staffordshire, ST5 5BG, United Kingdom.|ESRF, 71 avenue des Martyrs, 38000 Grenoble, France.
authors: Edward P
authors: EP
authors: Mitchell
mesh_terms: D001695:Biology / Q000379:methods*; D033363:Neutron Diffraction / Q000379:methods*; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*
chemical_list: D011506:Proteins