A probabilistic approach to space-group determination from powder diffraction data

Markvardsen, Anders J.; David, William I. F.; Johnson, Jordyn; Shankland, Kenneth

doi:10.1107/s0108767300012174

Cited by 112 publications

(120 citation statements)

References 3 publications

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“…Using positions extracted for the first 15 diffraction peaks a trigonal/ hexagonal unit-cell with dimensions of a ¼ 61:60 A, c ¼ 94:61 A was found using DICVOL [19], with figures of merit Mð15Þ ¼ 17:1 and Fð15Þ ¼ 115:9, indicating a substantially correct indexing [23]. A probabilistic approach for the space group determination [24] incorporated into DASH [25] indicated that the extinction symbol P3 1 should be chosen, giving possible chiral space groups P3 1 , P3 1 Table 1. Different structural models of the CHIKV nsP3 macro domain, native (3GPG) and complexed forms with ADP ribose (3GPO) or RNA (3GPQ) available in the PDB.…”

Section: Resultsmentioning

confidence: 99%

Preliminary insights into the non structural protein 3 macro domain of the Mayaro virus by powder diffraction

Papageorgiou¹,

Watier

Saunders

et al. 2010

Zeitschrift Für Kristallographie

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Abstract. We present preliminary structural results of the non-structural protein 3 (nsP3) macro domain from the Mayaro virus (MAYV), an emerging virus of South American tropic regions, by means of synchrotron X-ray powder diffraction. Indexing of the diffraction patterns indicate a trigonal/hexagonal lattice (a ¼ 61:60 A, c ¼ 94:61 A), analogous to the known lattice of the sequence homologous nsP3 macro domain from the Chikungunia virus (CHIKV), though MAYV must have looser molecular packing: the cell dimensions of MAYV are significantly altered in comparison to CHIKV and the unit cell comprises 6 molecules and 58% solvent. The results are discussed in terms of their methodological and biological importance.

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Section: Resultsmentioning

confidence: 99%

Preliminary insights into the non structural protein 3 macro domain of the Mayaro virus by powder diffraction

Papageorgiou¹,

Watier

Saunders

et al. 2010

Zeitschrift Für Kristallographie

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“…3). A less subjective approach to the problem has been outlined by Markvardsen et al [14]. In this approach, all the data (i.e., the extracted correlated integrated intensities from a Pawley fit to the diffraction data) are consulted and the probabilities of each of the possible extinction symbols (consistent with the crystal symmetry) relative to the extinction symbol possessing no systematic absences, is calculated.…”

Section: Space Group Determinationmentioning

confidence: 99%

Global Rietveld refinement

Shankland¹

2004

J. Res. Natl. Inst. Stand. Technol.

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Global optimisation methods of structure determination from powder diffraction data have risen to prominence in a relatively short space of time and they now constitute a key approach in the examination of polycrystalline molecular organic materials. A correctly formulated global optimisation approach may be regarded as a “global Rietveld refinement” that is capable of delivering accurate crystal structures from high-quality powder diffraction data. This paper focuses on how accuracy at all stages of a powder diffraction experiment impacts upon the overall structure solution process and particular attention is paid to assessing the degree of accuracy with which structures are returned from the global optimisation process.

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“…The diffraction pattern indexed to a monoclinic cell [M(20) = 95.7 F(20) = 253.2; DICVOL-91; Boultif & Louë r, 1991] and space group P2 1 was assigned from volume considerations and a statistical consideration of the systematic absences (Markvardsen et al, 2001). The data set was background subtracted and truncated to 59.8 2 for Pawley (1981) fitting ( 2 Pawley = 5.10) and the structure solved using the simulated annealing (SA) global optimization procedure, described previously (David et al, 1998), that is now implemented in the DASH computer program .…”

Section: Crystal Datamentioning

confidence: 99%

Powder study of (R)-1-phenylethylammonium (R)-2-phenylbutyrate form 3

et al. 2006

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Key indicatorsPowder X-ray study T = 298 K Mean (C-C) = 0.003 Å R factor = 0.026 wR factor = 0.031 For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e. The crystal structure of a new polymorph of the title compound, C 8 H 12 N + ÁC 10 H 11 O 2 À , was solved by simulated annealing from laboratory X-ray powder diffraction data, collected at 295 K. Subsequent Rietveld refinement using data collected to 1.54 Å resolution, yielded an R wp of 0.030. The compound crystallizes with one (R)-1-phenylethylammonium cation and one (R)-2-phenylbutyrate anion in the asymmetric unit. CommentThe title compound is known to crystallize in at least two polymorphic forms, form 1 (Brianso, 1978) and form 2 (Fernandes et al., 2006). A third polymorph, form 3, (I), was produced in situ by heating a polycrystalline sample of form 2 to 393 K. The sample remained stable upon cooling to 295 K and the powder data were collected at this temperature.The compound crystallizes in the monoclinic space group P2 1 with one (R)-1-phenylethylammonium cation and one Figure 1 The asymmetric unit of (I) with the atom-numbering scheme. Displacement spheres are shown at the 50% probability level. The dashed line indicates a hydrogen bond.

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A probabilistic approach to space-group determination from powder diffraction data

Cited by 112 publications

References 3 publications

Preliminary insights into the non structural protein 3 macro domain of the Mayaro virus by powder diffraction

Preliminary insights into the non structural protein 3 macro domain of the Mayaro virus by powder diffraction

Global Rietveld refinement

Powder study of (R)-1-phenylethylammonium (R)-2-phenylbutyrate form 3

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