Open AccessHigh‐resolution powder diffraction study of purple membrane with a large Guinier‐type camera
Author(s) -
Oka Toshihiko,
Miura Keiko,
Inoue Katsuaki,
Ueki Tatzuo,
Yagi Naoto
Publication year - 2006
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049506004766
Subject(s) - bacteriorhodopsin , diffraction , spring 8 , resolution (logic) , synchrotron , crystallography , materials science , optics , powder diffraction , x ray crystallography , synchrotron radiation , x ray , membrane , chemistry , beam (structure) , physics , beamline , biochemistry , artificial intelligence , computer science
X‐ray diffraction patterns from a film of oriented purple membranes, which comprise two‐dimensional crystals of bacteriorhodopsin (BR) trimers, were recorded with a 1 m‐pathlength Guinier‐type camera at SPring‐8 BL40B2. A well focused X‐ray beam and a camera with a high angular resolution of 0.024° enabled a powder diffraction profile with very sharp and well separated peaks to be obtained up to a resolution of 2.3 Å. Using integrated diffraction intensities up to a Bragg spacing of 4.2 Å, a cluster of bulky amino acid residues and the head group of the BR chromophore are apparent in the electron density map projected along the membrane normal. Thus, a combination of synchrotron X‐rays and large Guinier camera can be used for analyzing the conformational changes of BR in the intact state. In addition, the method might be extended to the structural analysis of film materials composed of two‐dimensional arrays of nanoparticles.