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In a previous study, a mutant of tyrosyl-tRNA synthetase in which a threonine residue (Thr51) was converted to proline dramatically improved the affinity of the enzyme for its ATP substrate. How does Pro51 improve the enzyme's affinity for ATP? A priori, Pro51 might interact directly with the ATP, or it might distort the polypeptide backbone and thereby(More)
The role of complementary hydrogen bonding as a determinant of biological specificity has been examined by protein engineering of the tyrosyl-tRNA synthetase. Deletion of a side chain between enzyme and substrate to leave an unpaired, uncharged hydrogen-bond donor or acceptor weakens binding energy by only 0.5-1.5 kcal mol-1. But the presence of an unpaired(More)
CD133/prominin-1 is a pentaspan transmembrane glycoprotein overexpressed in various solid tumours including colorectal and glioblastomas. CD133 was found here to be highly expressed in >or=50% of pancreatic, gastric and intrahepatic cholangiocarcinomas. Quantitative flow cytometric analysis showed that a panel of established hepatocellular, pancreatic and(More)
The Double Star Project is a collaboration between Chinese and European space agencies, in which two Chinese magnetospheric research spacecraft, carrying Chi-nese and European instruments, have been launched into equatorial (on 29 December 2003) and polar (on 25 July 2004) orbits designed to enable complementary studies with the Cluster spacecraft. The two(More)
This paper reexamines the relationship between aid and domestic tax revenues using a more recent and comprehensive dataset covering 118 countries for the period 1980–2009. Overall, our results support earlier findings of a negative association between net Official Development Assistance (ODA) and domestic tax revenues, but this relationship appears to have(More)
During the first quarter of 2001 the apogees of the Cluster spacecraft quartet precessed through midday local times. This provides the first opportunity for 4 spacecraft studies of the bow shock, magnetosheath and the day-side magnetopause current layer and boundary layers. In this paper, we present observations of electrons in the energy range ∼ 10 eV–26(More)
Pairs of stimuli taken from a psychometric measure of spatial aptitude were shown to 9-year-olds, 13-year-olds, and adults. The stimuli in pairs were (a) either identical or mirror images, and (b) presented in orientations that differed by 0-150 degrees. Individuals judged, as rapidly as possible, if the stimuli in a pair would be identical or mirror images(More)
The two PEACE (Plasma Electron And Current Experiment) sensors on board each Cluster spacecraft sample the electron velocity distribution across the full 4π solid angle and the energy range 0.7 eV to 26 keV with a time resolution of 4 s. We present high energy and angular resolution 3D observations of electrons of spacecraft origin in the various(More)
A single point mutation has been engineered in the tyrosyl-tRNA synthetase that improves its affinity (KM) for its substrate ATP by a factor of 100. In the crystal structure of the tyrosyl tRNA synthetase (of Bacillus stearothermophilus), the side-chain hydroxyl of Thr 51 appears to make a weak hydrogen bond with the AMP moiety of the substrate(More)