Home  About us  Contact
 

Home Source (home + source)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Getting the most out of X-ray home sources

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2005
A. L. Rojas
The structures of a 14,kDa phospholipase, an 18,kDa proteinase inhibitor and a novel glycoside hydrolase with molecular weight 60,kDa were solved using the SAD technique and the effects of the amount of anomalous signal, completeness and redundancy of data on heavy-atom substructure determination, phasing and model building were analyzed. All diffraction data sets were collected on a Cu-anode X-ray home source. The structure of the phospholipase was obtained using the anomalous scattering contribution from its 16 S atoms. Three-dimensional models for the other two macromolecules were obtained using the anomalous contribution of I atoms rapidly incorporated into the crystal through the quick cryo-soaking method of derivatization. These results were used to discuss the application of sulfur- and iodine-SAD approaches in combination with X-ray home sources for high-throughput protein crystal structure solution. The estimates of the anomalous signal from S atoms in the gene products of four genomes are given and the prospects for increasing the anomalous contribution using longer wavelengths (e.g. from a chromium home source) and quick cryo-soaking derivatization are discussed. The possibility of rapidly preparing tangible home-source isomorphous derivatives suggests that this approach might become a valuable tool in the future of post-genomic projects. [source]

Preliminary neutron and X-ray crystallographic studies of equine cyanomethemoglobin

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 4 2010
A. Y. Kovalevsky
Room-temperature and 100,K X-ray and room-temperature neutron diffraction data have been measured from equine cyanomethemoglobin to 1.7,Å resolution using a home source, to 1.6,Å resolution on NE-CAT at the Advanced Photon Source and to 2.0,Å resolution on the PCS at Los Alamos Neutron Science Center, respectively. The cyanomethemoglobin is in the R state and preliminary room-temperature electron and neutron scattering density maps clearly show the protonation states of potential Bohr groups. Interestingly, a water molecule that is in the vicinity of the heme group and coordinated to the distal histidine appears to be expelled from this site in the low-temperature structure. [source]

Crystallization and preliminary X-ray diffraction studies on the catalytic domain of the chick retinal neurite-inhibitory factor CRYP-2

ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 4 2005
T. S. Girish
The receptor protein tyrosine phosphatase CRYP-2 has been shown to be an inhibitory factor for the growth of retinal axons in the chick. The extracellular receptor domain of CRYP-2 contains eight fibronectin repeats and studies using the extracellular domain alone demonstrated the chemorepulsive effect on retinal neurons. The precise role of the intracellular catalytic domain and the mechanism by which its activity is regulated is not known. Determination of the structure of the catalytic domain of CRYP-2 was proposed in an effort to understand the downstream signal transduction mechanism in this system. The cloning, expression, purification and crystallization of the catalytic domain of CRYP-2 are now reported. Preliminary crystallographic studies were performed on the diamond-shaped crystals, which grew under oil using the microbatch method at 298,K. Native X-ray diffraction data were collected to 2.9,Å resolution on a home source. The crystals belong to the trigonal space group P3121, with unit-cell parameters a = b = 68.26, c = 244.95,Å. Assuming the presence of two molecules per asymmetric unit, the VM value was 2.7,Å3,Da,1 and the solvent content was 54.8%. [source]

Getting the most out of X-ray home sources

ACTA CRYSTALLOGRAPHICA SECTION D, Issue 8 2005
A. L. Rojas
The structures of a 14,kDa phospholipase, an 18,kDa proteinase inhibitor and a novel glycoside hydrolase with molecular weight 60,kDa were solved using the SAD technique and the effects of the amount of anomalous signal, completeness and redundancy of data on heavy-atom substructure determination, phasing and model building were analyzed. All diffraction data sets were collected on a Cu-anode X-ray home source. The structure of the phospholipase was obtained using the anomalous scattering contribution from its 16 S atoms. Three-dimensional models for the other two macromolecules were obtained using the anomalous contribution of I atoms rapidly incorporated into the crystal through the quick cryo-soaking method of derivatization. These results were used to discuss the application of sulfur- and iodine-SAD approaches in combination with X-ray home sources for high-throughput protein crystal structure solution. The estimates of the anomalous signal from S atoms in the gene products of four genomes are given and the prospects for increasing the anomalous contribution using longer wavelengths (e.g. from a chromium home source) and quick cryo-soaking derivatization are discussed. The possibility of rapidly preparing tangible home-source isomorphous derivatives suggests that this approach might become a valuable tool in the future of post-genomic projects. [source]