High-resolution X-ray diffraction data

The main sources of error in charge density studies based on high-resolution X-ray diffraction data are of an experimental nature when special care is taken to minimise them, charge density studies can achieve an accuracy better than 1% in the values of the structure factor amplitudes of the simplest structures [1, 2]. The errors for small molecular crystals, although more difficult to assess, are reckoned to be of the same order of magnitude. 

Scolecite gave the opportunity to relate the electron density features of Si-O-Si and Si-O-AI bonds to the atomic environment and to the bonding geometry. After the multipolar density refinement against Ag Ka high resolution X-ray diffraction data, a kappa refinement was carried out to derive the atomic net charges in this compound. Several least-squares fit have been tested. The hat matrix method which is presented in this paper, has been particularly efficient in the estimation of reliable atomic net charges in scolecite. 

Figure 7.11 Pictures obtained with high-resolution X-ray diffraction data of G-wire of d(TG4T) (left) and the B-DNA duplex of d(CGCGAATTCGCG). (Reprinted with permission of Wiley— VCH from Chemistry—A European Journal, Vol. 6, p. 3249 ad ff., copyright 2000.)...

There are three methods of collecting high-resolution X-ray diffraction data diffractometry, photographically, and by electronic area detector. Each method has advantages and disadvantages for a particular crystalline protein, but for very accurate data acquisition beyond 2 A... 

The crystallographic results of Blake et al. (1983), who analyzed high-resolution X-ray diffraction data for human lysozyme (HL) and tortoise egg white lysozyme (TEWL) fit the above picture. The crystallographic... 

Sikorski, R, Hori, R., and M. Wada. 2009. Revisit of a-chitin crystal structure using high resolution x-ray diffraction data. Biomacromolecules 10 1100-1105. 

Koritsanszky et al collected high-resolution X-ray diffraction data at 15 K for potassium hydrogen (-l-)-tartrate. Three refinement models were tested to examine how the data resolution and restrictions on the anisotropic displacement parameters affect the topology of the static densities. The Laplacian distribution, especially for the polar bonds, was found to be highly sensitive to the resolution of the data included in the fit and to the treatment of the displacement amplitudes. 

Biological. - Pichon-Pesme et /. determined the electron density and electrostatic properties of Tyr-Gly-Gly and Gly-Asp from high-resolution X-ray diffraction data at 123 K. Topological properties of the charge distribution are diseussed and compared with those derived from other experimental studies on peptide molecules, and the characteristics of the BCPs of the C=0, C-N and C-C bonds are analysed. 

Kubicki JD, Sykes D, Apitz SE (1999) Ab initio calcttlation of aqueous alitmimtm and alurrrinrrm-carboxylate complex energetics and Al-27 NMR shifts. J Phys Chem A 103 903-915 Kuntzinger S, Ghermani NE, Dusausoy Y, Lecomte C (1998) Distribution and topology of the electron density in a aluminosilicate compoimd from high resolution X-ray diffraction data the case of scolecite. ActaCrystB 54 819-833... 

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