IUCr Newsletter - Volume 20, Number 2 - (Page 2)
Acta Cryst. (2012). A68, 366–381 (http://doi.org/hxm)
Classifying and assembling two-dimensional X-ray laser diffraction patterns of a single particle to reconstruct the three-dimensional diffraction intensity function: resolution limit due to the quantum noise
A. TokuhisA, J. TAkA, h. kono And n. Go
New X-ray free-electron laser light sources offer a possibility of highresolution single-particle imaging from repeated measurements of twodimensional diffraction intensity patterns, each from a target with an unknown random orientation. An algorithm is developed to assemble these patterns into the three-dimensional diffraction intensity function. A key is the calculation of a newly defined correlation function for a pair of diffraction patterns to detect their similarity. The result indicates that, if the current laser light beam can be further focused, a subnanometer resolution structural determination may be possible.
Correlation function of a pair of simulated diffraction patterns for a small protein, lysozyme. When a pair is similar, a high correlation line is observed. The highest k value, up to which the line can be detected against noise, determines the resolution of structural determination.
Acta Cryst. (2012). B68, 171–181 (http://doi.org/hxn)
Ab-initio crystal structure analysis and refinement approaches of oligo p-benzamides based on electron diffraction data
T.E. GorElik, J. vAn dE sTrEEk, A.F.M. kilbinGEr, G. brunklAus And u. kolb
Ab-initio crystal structure analysis of organic materials from electron diffraction data, collected using the automated electron diffraction tomography (ADT) technique, is presented. The structure solution and refinement route was first validated for the known crystal structure of tri-p-benzamide. The procedure was then applied to the structure analysis of tetra-p-benzamide, where an unusual hydrogen-bonding scheme was found, in perfect agreement with solid-state NMR data. The presented procedure can generally be applied for crystal structure analysis of organic nanocrystalline materials.
Acta Cryst. (2012). C68, o156–o159 (http://doi.org/hxp)
Pseudopolymorphism in hydroxybenzophenones: the dihydrate of 2,2’,4,4’-tetrahydroxybenzophenone
i.M.r. lAndrE, F.T. MArTins, J.A. EllEnA, M.h. dos sAnTos And A.C. doriGuETTo
To increase our knowledge of polymorphism in molecular compounds and pharmaceuticals we have committed ourselves to studying hydroxybenzophenone derivatives. The paper describes the structure of a dihydrate pseudopolymorph of 2,2´,4,4´-tetrahydroxybenzophenone or bis(2,4-dihydroxyphenyl)methanone, which was compared with the known anhydrous and hydrated forms of other hydroxybenzophenones. The role of water in the crystal assembly was also studied.
Acta Cryst. (2012). D68, 511–520 (http://doi.org/hxq)
Peptide inhibitors of botulinum neurotoxin serotype A: design, inhibition, cocrystal structures, structure–activity relationship and pharmacophore modeling
G. kuMAr, d. kuMArAn, s.A. AhMEd And s. swAMinAThAn
Botulinum neurotoxin (BoNT) is one of the most poisonous biological substances known to humans with no drugs available in the market today for post-intoxication treatment. Efforts continue as illustrated by Kumar et al. to develop inhibitors against the BoNT protease activity that disrupts the SNARE assembly and thus the release of neurotransmitters at neuromuscular junctions. They designed and tested a number of peptide inhibitors against the toxic action. The article illustrates the key pharmacophore features using the high-resolution crystal structures of a few peptide–BoNT complexes.
Crystal structures of peptide inhibitors with BoNT/A. A close-up view of the BoNT/A active site with peptides is shown.
IUCr Newsletter ♦ Volume 20, Number 2 ♦ 2012
Table of Contents for the Digital Edition of IUCr Newsletter - Volume 20, Number 2
IUCr Newsletter - Volume 20, Number 2
Letter from the President
XX Congress Reports
Regional Associate News
Crystallographic Meeting Reports
Awards, News and Notices
Index to Advertisers
Crystall Ographic Meetings Calendar
IUCr Newsletter - Volume 20, Number 2