George M. Sheldrick

Bio: George M. Sheldrick is an academic researcher from University of Göttingen. The author has contributed to research in topics: Crystal structure & Bond length. The author has an hindex of 58, co-authored 791 publications receiving 151229 citations. Previous affiliations of George M. Sheldrick include University of Regensburg.

Automatic solution of heavy-atom substructures.

Abstract: Publisher Summary The determination of heavy-atom substructures using multiwavelength anomalous dispersion (MAD) or multiple isomorphous replacement (MIR) data is a straightforward, although often lengthy, process. SOLVE is designed to automate fully the analysis of such data. The MAD and MIR approaches to structure solution are conceptually similar and share several important steps. In each method, trial partial structures for heavy or anomalously scattering atoms are often obtained by the inspection of difference-Patterson functions or by semiautomated analysis. These initial structures are refined against the observed data and are used to generate initial phases. Then, additional sites and sites in other derivatives can be found from weighted difference or gradient maps using these phases. SOLVE prepares data for a heavy-atom substructure solution in two steps. First, the data are scaled using the local scaling procedure of Matthews and Czerwinski. Second, MAD data are converted to a pseudo-single isomorphous replacement with anomalous scattering (SIRAS) form that permits more rapid analysis. In many cases, an analysis of heavy-atom sites by the sequential deletion of individual sites or derivatives is also an important criterion of quality.

Structure of the lipopeptide antibiotic tsushimycin.

Abstract: The amphomycin derivative tsushimycin has been crystallized and its structure determined at 1.0 A resolution. The asymmetric unit contains 12 molecules and with 1300 independent atoms this structure is one of the largest solved using ab initio direct methods. The antibiotic is comprised of a cyclodecapeptide core, an exocyclic amino acid and a fatty-acid residue. Its backbone adopts a saddle-like conformation that is stabilized by a Ca2+ ion bound within the peptide ring and accounts for the Ca2+-dependence of this antibiotic class. Additional Ca2+ ions link the antibiotic molecules to dimers that enclose an empty space resembling a binding cleft. The dimers possess a large hydrophobic surface capable of interacting with the bacterial cell membrane. The antibiotic daptomycin may exhibit a similar conformation, as the amino-acid sequence is conserved at positions involved in Ca2+ binding.

Crystal structure of low-potential cytochrome c549 from Synechocystis sp. PCC 6803 at 1.21 A resolution.

Abstract: The crystal structure of low-potential cytochrome c 549, an extrinsic component of the photosystem II (PS II) from Synechocystis sp. PCC 6803, was obtained directly from single-wavelength 1.21 A resolution diffraction data. This is the first monodomain bis-histidinyl monoheme cytochrome c to be structurally characterized. The extended N-terminal region of c 549 builds up a two-strand antiparallel β-sheet in a hairpin motif, which extends through two molecules owing to crystal packing. Both peptide termini are involved in crystal contacts, which may explain their protrusion out of the globular fold. The C-terminus is preceded by a 9 A-long hydrophobic finger extending from a positively charged base and could be involved in PSII interactions, as well as a protruding negative patch built by a set of conserved acidic residues among c 549 sequences.

Tris(pentafluorophenyl)gold(III) complexes

Abstract: The preparation of [Au(C6F5)3(tht)](tht = tetrahydrothiophen) by oxidation of [Au(C6F5)(tht)] with [Tl(C6F5)2Cl] is described. Displacement of tht by other neutral or anionic unidentate ligands leads to the synthesis of [Au(C6F5)3L][L = NH3, py, PMePh2, P(OPh)3, AsPh3, SbPh3 or CNC6H4Me-p] or Q[Au(C6F5)3X][Q = NEt4, NBu4, PPh3(CH2Ph), or N(PPh3)2; X = Cl, I, SCN, or N3]. The compound [Au(C6H5)3(CNC6H4Me-p)] adds amines to give the gold(III)–carbene complexes [Au(C6F5)3{C(NHC6H4Me-p)(NR2)}](NR2= NHC6H4Me-p, NEt2, or NHCH2CH2NH2). The reaction of the compound [Au(C6F5)3(tht)] with potentially bidentate ligands takes two different courses. (a)o-Phenylenebis(dimethylarsine)(pdma) and 1,2-bis(diphenylphosphino)methane (dppm) give four-co-ordinated complexes, in which the ligands are unidentate; the pdma complex has inequivalent methyl hydrogens at low temperature (1H n.m.r.) and the dppm complex inequivalent P atoms (31P n.m.r.). An X-ray structure of the pdma complex confirms four-co-ordination in the solid state; space group P21/n, a= 10.796(3), b= 17.347(6), c= 16.275(5)A, β= 94.47(3)°, Z= 4, R= 0.058 for 3 357 reflections. (b) 1,2-Bis(diphenylphosphino)ethane (dppe) acts as a bridging ligand leading to the formation of [(C6F5)3Au(µ-dppe)Au(C6F5)3]. Similar reactions starting from [Au(C6F5)(2,4,6-C6F3H2)2(tht)] lead to the compounds [Au(C6F5)(2,4,6-C6F3H2)2(PPh3)] or [NBu4][Au(C6F5)(2,4,6-C6F3H2)2Br]. The arylation of [Au(C6F5)3Cl]– or [Au(C6F5)(2,4,6-C6F3H2)2Br]– with Ag(C6F5) leads to [Au(C6F5)4]– and [Au(C6F5)2(2,4,6-C6F3H2)2]– respectively.

A short history of SHELX

Abstract: An account is given of the development of the SHELX system of computer programs from SHELX-76 to the present day. In addition to identifying useful innovations that have come into general use through their implementation in SHELX, a critical analysis is presented of the less-successful features, missed opportunities and desirable improvements for future releases of the software. An attempt is made to understand how a program originally designed for photographic intensity data, punched cards and computers over 10000 times slower than an average modern personal computer has managed to survive for so long. SHELXL is the most widely used program for small-molecule refinement and SHELXS and SHELXD are often employed for structure solution despite the availability of objectively superior programs. SHELXL also finds a niche for the refinement of macromolecules against high-resolution or twinned data; SHELXPRO acts as an interface for macromolecular applications. SHELXC, SHELXD and SHELXE are proving useful for the experimental phasing of macromolecules, especially because they are fast and robust and so are often employed in pipelines for high-throughput phasing. This paper could serve as a general literature citation when one or more of the open-source SHELX programs (and the Bruker AXS version SHELXTL) are employed in the course of a crystal-structure determination.

Crystal structure refinement with SHELXL

Abstract: The improvements in the crystal structure refinement program SHELXL have been closely coupled with the development and increasing importance of the CIF (Crystallographic Information Framework) format for validating and archiving crystal structures. An important simplification is that now only one file in CIF format (for convenience, referred to simply as `a CIF') containing embedded reflection data and SHELXL instructions is needed for a complete structure archive; the program SHREDCIF can be used to extract the .hkl and .ins files required for further refinement with SHELXL. Recent developments in SHELXL facilitate refinement against neutron diffraction data, the treatment of H atoms, the determination of absolute structure, the input of partial structure factors and the refinement of twinned and disordered structures. SHELXL is available free to academics for the Windows, Linux and Mac OS X operating systems, and is particularly suitable for multiple-core processors.

OLEX2: a complete structure solution, refinement and analysis program

Abstract: New software, OLEX2, has been developed for the determination, visualization and analysis of molecular crystal structures. The software has a portable mouse-driven workflow-oriented and fully comprehensive graphical user interface for structure solution, refinement and report generation, as well as novel tools for structure analysis. OLEX2 seamlessly links all aspects of the structure solution, refinement and publication process and presents them in a single workflow-driven package, with the ultimate goal of producing an application which will be useful to both chemists and crystallographers.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

PHENIX: a comprehensive Python-based system for macromolecular structure solution

Abstract: Macromolecular X-ray crystallography is routinely applied to understand biological processes at a molecular level. How­ever, significant time and effort are still required to solve and complete many of these structures because of the need for manual interpretation of complex numerical data using many software packages and the repeated use of interactive three-dimensional graphics. PHENIX has been developed to provide a comprehensive system for macromolecular crystallo­graphic structure solution with an emphasis on the automation of all procedures. This has relied on the development of algorithms that minimize or eliminate subjective input, the development of algorithms that automate procedures that are traditionally performed by hand and, finally, the development of a framework that allows a tight integration between the algorithms.