Linked Life Data

9231895

Source:http://linkedlifedata.com/resource/pubmed/id/9231895

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1997-8-15
pubmed:abstractText
The title compound Ta6Br(2+)12 is of interest for the analysis of biological structures as a heavy-metal derivative with great potential for the structure determination of large protein systems. In macromolecular crystallography the phases of the measured structure factor amplitudes have to be determined. The most widely used method for novel structures is isomorphous replacement by introducing electron-rich compounds into the protein crystals. These compounds produce measurable changes of the diffraction intensities, which allow phase determination. We synthetized the Ta6Br(2+)12 cluster in high yields, crystallized it, and determined its crystal structure by X-ray diffraction analysis at atomic resolution. The cluster is a regular octahedron consisting of six metal atoms with 12 bridging bromine atoms along the 12 edges of the octahedron. The cluster is compact, of approximately spherical shape with about 4.3 A radius and highly symmetrical. One Ta6Br(2+)12 ion adds 856 electrons to a protein, a considerable contribution to the scattering power even of large proteins or multimeric systems. At low resolution all atoms of the cluster scatter in phase and act as a super heavy-atom, which is easy to locate in the difference Patterson map. We investigated its binding sites in the biologically significant high-resolution structures of an antibody V(L) domain, dimethyl sulfoxide reductase, GTP-cyclohydrolase I, and the proteasome. With the randomly oriented cluster, treated as a single site scatterer, phases could be used only up to 6 A resolution. In contrast, when the cluster is correctly oriented, phases calculated from its 18 atom sites can be used to high resolution. We present the atomic structure of the Ta6Br(2+)12, describe a method to determine its localization and orientation in the unit cell of protein crystals of two different proteins, and analyse its phasing power. We show that phases can be calculated to high resolution. The phase error is lower by more than 30 degrees compared to the single site approximation, using a resolution of 2.2 A. Furthermore, Ta6Br(2+)12 has two different strong anomalous scatterers tantalum and bromine to be used for phase determination.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
http://linkedlifedata.com/resource/pubmed/chemical/Bromides, http://linkedlifedata.com/resource/pubmed/chemical/Cysteine Endopeptidases, http://linkedlifedata.com/resource/pubmed/chemical/GTP Cyclohydrolase, http://linkedlifedata.com/resource/pubmed/chemical/Immunoglobulin Light Chains, http://linkedlifedata.com/resource/pubmed/chemical/Immunoglobulin Variable Region, http://linkedlifedata.com/resource/pubmed/chemical/Iron-Sulfur Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Multienzyme Complexes, http://linkedlifedata.com/resource/pubmed/chemical/Oxidoreductases, http://linkedlifedata.com/resource/pubmed/chemical/Proteasome Endopeptidase Complex, http://linkedlifedata.com/resource/pubmed/chemical/Proteins, http://linkedlifedata.com/resource/pubmed/chemical/Tantalum, http://linkedlifedata.com/resource/pubmed/chemical/dimethyl sulfoxide reductase, http://linkedlifedata.com/resource/pubmed/chemical/tantalum bromide
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0022-2836
pubmed:author
pubmed:issnType
Print
pubmed:day
4
pubmed:volume
270
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1-7
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
Ta6Br(2+)12, a tool for phase determination of large biological assemblies by X-ray crystallography.
pubmed:affiliation
Max-Planck-Institut fur Biochemie, Abteilung Strukturforschung, Martinsried, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't