Journal ArticleDOI
Evaluation of Single-Crystal X-ray Diffraction Data from a Position-Sensitive Detector
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TLDR
In this paper, a Fortran program is developed for the reduction of single-crystal diffraction data from a sequence of adjacent rotation pictures recorded at a fixed X-ray wavelength by an electronic area detector.Abstract:
A Fortran program has been developed for the reduction of single-crystal diffraction data from a sequence of adjacent rotation pictures recorded at a fixed X-ray wavelength by an electronic area detector. The electronic pictures (data frames) covering the first 5° of crystal rotation are used to locate strong diffraction spots and to estimate the background. The orientation of the crystal is derived automatically from the list of observed spots and all parameters describing the diffraction pattern are refined. The only input required from the user is the specification of the space group, approximate cell dimensions and detector setting. When the initialization step is finished the program goes back to the first picture and evaluates all data frames in the order they arrive from the measurement. Each element of an electronic picture (pixel) is labelled by the indices of the nearest reflection using the current refined parameters describing the diffraction geometry. If the pixels close to its nearest reflection the counts contribute to the three-dimensional profile; otherwise the counts are used to update the background. Each profile is represented as if the reflection had followed the shortest path through the Ewald sphere and had been recorded on the surface of the sphere. Reflections close to the Ewald sphere are kept in a hash table to allow rapid access for updating the profiles. Reflections which have completely passed through the Ewald sphere are removed from the table and saved for further processing. Intensities are estimated by fitting their profiles to an average shape learned from strong neighbouring reflections. Smoothly varying scaling factors are applied to the Lp-corrected intensities which minimize discrepancies between symmetry-related reflections and fit to a reference data set if available.read more
Citations
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Book ChapterDOI
Processing of X-ray diffraction data collected in oscillation mode
Zbyszek Otwinowski,Wladek Minor +1 more
TL;DR: The methods presented in the chapter have been applied to solve a large variety of problems, from inorganic molecules with 5 A unit cell to rotavirus of 700 A diameters crystallized in 700 × 1000 × 1400 A cell.
Journal ArticleDOI
Two-dimensional detector software: From real detector to idealised image or two-theta scan
TL;DR: Calibration methods and software have been developed for single crystal diffraction experiments, using both approaches for calibrate, and apply corrections, to obtain accurate angle and intensity information.
Journal ArticleDOI
Scaling and assessment of data quality
TL;DR: The various physical factors affecting measured diffraction intensities are discussed, as are the scaling models which may be used to put the data on a consistent scale and algorithms used by the CCP4 scaling program SCALA.
Journal ArticleDOI
Atomic structure of acetylcholinesterase from Torpedo californica: a prototypic acetylcholine-binding protein
Joel L. Sussman,Michal Harel,Felix Frolow,Christian Oefner,Adrian Goldman,Lilly Toker,Israel Silman +6 more
TL;DR: Modeling of acetylcholine binding to the enzyme suggests that the quaternary ammonium ion is bound not to a negatively charged "anionic" site, but rather to some of the 14 aromatic residues that line the gorge.
Journal ArticleDOI
Human Growth Hormone and Extracellular Domain of Its Receptor: Crystal Structure of the Complex
TL;DR: Examination of the 2.8 angstrom crystal structure of the complex between the hormone and the extracellular domain of its receptor (hGHbp) showed that the complex consists of one molecule of growth hormone per two molecules of receptor.
References
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Book
Theory of X-Ray Diffraction in Crystals
TL;DR: A classie work, so thoroughly revised as to be essentially a new book as mentioned in this paper, has been published, which includes: a new mineral classification; a new elastic series of classification numbers for species; new data derived from x-ray crystallography, and a new form of presentation of crystallographic data; revision of specific gravities, based on new observations; introduction of the optical characters of the opaque minerals; new chemical treatment of species.