University of Mons

About: University of Mons is a education organization based out in Mons, Belgium. It is known for research contribution in the topics: Large Hadron Collider & Standard Model. The organization has 3073 authors who have published 9465 publications receiving 294776 citations.

Characterization of the ligand-binding site of the transferrin receptor in Trypanosoma brucei demonstrates a structural relationship with the N-terminal domain of the variant surface glycoprotein.

Abstract: The Trypanosoma brucei transferrin (Tf) receptor is a heterodimer encoded by ESAG7 and ESAG6, two genes contained in the different polycistronic transcription units of the variant surface glycoprotein (VSG) gene. The sequence of ESAG7/6 differs slightly between different units, so that receptors with different affinities for Tf are expressed alternatively following transcriptional switching of VSG expression sites during antigenic variation of the parasite. Based on the sequence homology between pESAG7/6 and the N-terminal domain of VSGs, it can be predicted that the four blocks containing the major sequence differences between pESAG7 and pESAG6 form surface-exposed loops and generate the ligand-binding site. The exchange of a few amino acids in this region between pESAG6s encoded by different VSG units greatly increased the affinity for bovine Tf. Similar changes in other regions were ineffective, while mutations predicted to alter the VSG-like structure abolished the binding. Chimeric proteins containing the N-terminal dimerization domain of VSG and the C-terminal half of either pESAG7 or pESAG6, which contains the ligand-binding domain, can form heterodimers that bind Tf. Taken together, these data provided evidence that the T.brucei Tf receptor is structurally related to the N-terminal domain of the VSG and that the ligand-binding site corresponds to the exposed surface loops of the protein.

XPS study of TiOx thin films prepared by d.c. magnetron sputtering in Ar–O2 gas mixtures

Abstract: Titanium oxide films have been deposited, at a pressure of 5 mTorr and a discharge current of 500 mA, on borosilicate glass substrates. We have studied in situ by XPS the dependence of film composition on oxygen partial pressure. All the experiments have been performed under high vacuum; there is no air contamination of film surfaces before XPS analysis. The ions produced in the plasma have been analysed by glow discharge mass spectrometry (GDMS). The stoichiometry of the films is compared to the plasma composition. The XPS results show that for an increasing oxygen partial pressure four regimes are observed. At very low oxygen concentration ( 15% (zone IV) a pure TiO 2 film is obtained. When zone IV starts, the Ti + mass spectrometric signal is still higher than the TiO + signal, showing that a pure TiO 2 phase is occurring at the substrate while the sputtering mode is still partially metallic.