RESUMO
The 2.7 A structure of the tetanus neurotoxin receptor binding fragment Hc reveals a jelly-roll domain and a beta-trefoil domain. Hc retains the unique transport properties of the holotoxin and is capable of eliciting a protective immunological response against the full length holotoxin.
Assuntos
Proteínas de Membrana/química , Estrutura Secundária de Proteína , Toxina Tetânica/química , Sequência de Aminoácidos , Animais , Sítios de Ligação , Simulação por Computador , Cristalografia por Raios X , Proteínas de Membrana/metabolismo , Modelos Moleculares , Modelos Estruturais , Dados de Sequência Molecular , Neurônios/metabolismo , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/imunologia , Deleção de Sequência , Software , Toxina Tetânica/imunologiaRESUMO
6-O-alpha-D-Galactopyranosyl-D-glucopyranose (melibiose) derivatives with alkyl groups at the terminal 1-O and 6'-O positions have been synthesized. They show thermotropic and lyotropic liquid-crystal properties. The d-spacings of the strong inner X-ray diffraction rings correspond to approximately 0.9 times the extended length of the molecule. The molecules are therefore either extended in monomolecular layers or U-shaped in bimolecular layers.
Assuntos
Melibiose/análogos & derivados , Melibiose/química , Alquilação , Calorimetria , Sequência de Carboidratos , Cristalografia por Raios X , Dissacarídeos/química , Espectroscopia de Ressonância Magnética , Microscopia , Dados de Sequência MolecularRESUMO
The crystal structure of ethyl 2,3-dideoxy-alpha-D-erythro-hex-2-enopyranoside, C8H14O4, is orthorhombic, P2(1)2(1)2(1), with cell dimensions at 123 K [293 K] a = 11.220(2) [11.319(1)], b = 18.387(3) [18.458(2)], c = 8.509(2) [8.635(1)] A, Z = 8. There are two symmetry-independent molecules in the asymmetric unit. In both molecules, the conformation is oH5. The alkenic bond is almost exactly planar in one molecule, with C-1--C-2--C-3--C-4 = +0.8 degrees. In the other molecule, this torsion angle is +3.7 degrees. The glycosidic torsion angle, O-5--C-1--O-1--C-7, has normal exoanomeric values of +71 and +64 degrees. The conformation of the ethoxyl group is extended, with C-1--O-1--C-7--C-8 = +162 and +170 degrees. The primary alcohol group has different orientations, g/t on one molecule, g/g on the other. The characteristic glycosidic bond-shortening observed in the pyranosides is modified in this enopyranoside. Both the ring bond, O-5--C-1, and the glycosidic bond, C-1--O-1, are short, with distances ranging from 1.409 to 1.425 A. Solution and solid-state c.p.-m.a.s., 13C-n.m.r. spectra are reported.