title: X-ray spectroscopy and X-ray diffraction at wavelengths near the K-absorption edge of phosphorus.
abstract: Phosphorus is an abundant element in living organisms. It is traceable by its X-ray absorption spectrum which shows a strong white line at its K-edge, comparable with that observed for the L(III) edges of rare earth ions. With purple membrane, the variation of the imaginary part of the anomalous dispersion of phosphorus is found to be close to 20 anomalous electron units. Anomalous diffraction experiments at wavelengths near the K-absorption edge of phosphorus confirm this result. The spatial distribution of lipids derived from anomalous diffraction agrees with earlier results from neutron diffraction. Test experiments on single crystals of the carrier protein using 5.76 A photons gave a first low-resolution diffraction pattern. Various techniques of crystal mounting were attempted. In addition, fluorescence measurements on a solution of threonine synthase appear to hint at a change of the phosphate environment of the cofactor upon activator binding.
authors.affiliation: Laboratoire d'Enzymologie et de Biochimie Structurales CNRS, Avenue de la Terrasse, 91198 Gif sur Yvette CEDEX, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Biou
authors.forename: Peter
authors.initials: P
authors.lastname: Bösecke
authors.forename: Jean Marie
authors.initials: JM
authors.lastname: Bois
authors.forename: Gérard
authors.initials: G
authors.lastname: Brandolin
authors.forename: Richard
authors.initials: R
authors.lastname: Kahn
authors.forename: Corinne
authors.initials: C
authors.lastname: Mas
authors.forename: Lionel
authors.initials: L
authors.lastname: Nauton
authors.forename: Hugues
authors.initials: H
authors.lastname: Nury
authors.forename: Eva
authors.initials: E
authors.lastname: Pebay-Peyroula
authors.forename: Jean
authors.initials: J
authors.lastname: Vicat
authors.forename: Heinrich
authors.initials: H
authors.lastname: Stuhrmann
mesh_terms: D019757:Carbon-Oxygen Lyases / Q000032:analysis / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006217:Halobacterium / Q000737:chemistry; D000226:Mitochondrial ADP, ATP Translocases / Q000032:analysis / Q000737:chemistry*; D008968:Molecular Conformation; D010758:Phosphorus / Q000032:analysis* / Q000737:chemistry; D011487:Protein Conformation; D018717:Purple Membrane / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission / Q000295:instrumentation* / Q000379:methods*; D014961:X-Ray Diffraction / Q000295:instrumentation* / Q000379:methods*
chemical_list: D010758:Phosphorus; D000226:Mitochondrial ADP, ATP Translocases; D019757:Carbon-Oxygen Lyases; C023160:threonine synthase