Showing papers by "George M. Sheldrick published in 2008"
TL;DR: This paper could serve as a general literature citation when one or more of the open-source SH ELX programs (and the Bruker AXS version SHELXTL) are employed in the course of a crystal-structure determination.
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.
81,116 citations
TL;DR: X-ray structures of the periplasmic sensor domain of CitA in the citrate-free andcitrate-bound states are reported and it is shown that ligand binding causes a considerable contraction of the sensor domain.
124 citations
TL;DR: 5-Amino-2,4,6-triiodoisophthalic acid, in which three covalently bound iodines form an equilateral triangle, was incorporated into proteins in order to obtain phases by single-wavelength anomalous dispersion (SAD), has an improved binding capability compared with simple heavy-metal ions.
Abstract: Obtaining phase information for the solution of macromolecular structures is still one of the bottlenecks in X-ray crystallography. 5-Amino-2,4,6-triiodoisophthalic acid (I3C), in which three covalently bound iodines form an equilateral triangle, was incorporated into proteins in order to obtain phases by single-wavelength anomalous dispersion (SAD). An improved binding capability compared with simple heavy-metal ions, ready availability, improved recognition of potential heavy-atom sites and low toxicity make I3C particularly suitable for experimental phasing.
73 citations
TL;DR: The homologue of the phosphoprotein PII phosphatase PphA from Thermosynechococcus elongatus, termed tPphA, was identified and its structure was resolved in two different space groups, at a resolution of 1.28 and 3.05 A, implying that the flap domain is involved in substrate binding and catalytic activity.
64 citations
TL;DR: A crystal structure is reported that shows an antibiotic that extracts a nucleobase from a DNA molecule ‘caught in the act’ after forming a covalent bond but before departing with the base.
Abstract: We report a crystal structure that shows an antibiotic that extracts a nucleobase from a DNA molecule 'caught in the act' after forming a covalent bond but before departing with the base. The structure of trioxacarcin A covalently bound to double-stranded d(AACCGGTT) was determined to 1.78 A resolution by MAD phasing employing brominated oligonucleotides. The DNA-drug complex has a unique structure that combines alkylation (at the N7 position of a guanine), intercalation (on the 3'-side of the alkylated guanine), and base flip-out. An antibiotic-induced flipping-out of a single, nonterminal nucleobase from a DNA duplex was observed for the first time in a crystal structure.
30 citations
TL;DR: Crystals of the cytotoxic thionin proteins viscotoxins A1 and B2 extracted from mistletoe diffracted to high resolution are excellent candidates for testing crystallographic methods and sulfur-SAD phasing provided a convincing solution for viscotoxin A1.
Abstract: Crystals of the cytotoxic thionin proteins viscotoxins A1 and B2 extracted from mistletoe diffracted to high resolution (1.25 and 1.05 A, respectively) and are excellent candidates for testing crystallographic methods. Ab initio direct methods were only successful in solving the viscotoxin B2 structure, which with 861 unique non-H atoms is one of the largest unknown structures without an atom heavier than sulfur to be solved in this way, but sulfur-SAD phasing provided a convincing solution for viscotoxin A1. Both proteins form dimers in the crystal and viscotoxin B2 (net charge +4 per monomer), but not viscotoxin A1 (net charge +6), is coordinated by sulfate or phosphate anions. The viscotoxin A1 crystal has a higher solvent content than the viscotoxin B2 crystal (49% as opposed to 28%) with solvent channels along the crystallographic 4(3) axes.
29 citations
TL;DR: The title compound, C8H4I3NO4·H2O, shows an extensive hydrogen-bond network; in the crystal structure, molecules are linked by O—H⋯O, N—H→N and O–H–N hydrogen bonds involving all possible donors and also the water molecule.
Abstract: The title compound, C8H4I3NO4·H2O, shows an extensive hydrogen-bond network; in the crystal structure, molecules are linked by O—H⋯O, N—H⋯O and O—H⋯N hydrogen bonds involving all possible donors and also the water molecule.
14 citations