DYNAMICS OF WATER-MOLECULES IN BARIUM NITROPRUSSIDE TRIHYDRATE STUDIED AT LOW-TEMPERATURE BY PROTON NMR
MOLECULAR PHYSICS
Authors: TRITTGOC, J; PISLEWSKI, N
Abstract
Single crystals of barium nitroprusside trihydrate (BaNP) were investigated by Fourier transform 'wide-line' NMR at 40 K and by proton spin-lattice relaxation time in the temperature range from 320 to 30 K. The analysis of the spectra yielded the dipolar-dipolar (DD) coupling tensors of three different water molecules. Two of the DD tensors show the asymmetry parameters eta = 0.08 and 0.09. These results are interpreted in terms of librational motions of the water molecules. A model for such motions is proposed and the angles of librations are calculated The positions of the proton-proton vectors in the unit cell of the crystal obtained from DD tensors coincide with the neutron diffraction data of BaNP. The proton spin-lattice relaxation times T-1 at low temperatures were interpreted in terms of the dipole-dipole interactions modulated by the oscillation of the proton-proton vector between two minima of an asymmetric double-well potential. The following parameters for this motion have been obtained: E(a), = 3.4 kJ mol(-1), tau(0), = 3.9 x 10(-13) s and Delta E = 1.50 kJ mol(-1).
Identification and molecular analysis of BANP
GENE
Authors: Birot, AM; Duret, L; Bartholin, L; Santalucia, B; Tigaud, I; Magaud, JP; Rouault, JP
Abstract
BTG3 belongs to a family of structurally related genes whose biochemical functions remain elusive. In order to investigate the mechanism underlying BTG3-mediated functions, we tried to identify BTG3 potential partners. The use of the yeast 'two-hybrid system', with BTG3 as bait, enabled us to isolate BANP (BTG3 Associated Nuclear Protein). Other commonly used protein-binding assays did not confirm this yeast interaction. However, BANP had never been described before. and this prompted us to further characterise this gene. In this paper, we present data on its molecular organization in mouse, then we speculate on the nature of this nuclear protein, and finally we localise BANP on the human chromosome 16q24 subregion; we discuss the fact that frequent loss of heterozygosity within this legion has been observed in different tumours. (C) 2000 Elsevier Science B.V. All rights reserved.