Enkephalin is a morphine-like pentapeptide: Tyr-Gly-Gly-Phe-Xxx, Xxx=Met or Leu. To consider the relationship between the enkephalin conformation and the opioid receptor, the crystal structures of enkephalin analogues were analyzed by the X-ray diffraction method, and two characteristic forms were observed as the fundamental conformation of enkephalin, One is the β-turn structllre and the other the antiparallelly extended dimer (ED) structure. From the NMR and CD spectral studies, it was suggested that the β-turn and ED structures of enkephalin are the most probable conformations for the binding to μ-and δ-receptors, respectively. Further, the molecular-dynamics simulations indicated that these conformation are both advantageous in energetical term. Based on the insight of the enkephalin conformation, it was attempted to convert the μ-selective morphine toward δ-affinitive ligand by the dimerization.
Three different crystals of 9-ethyl-8-hydroxyguanine have been analysed by X-ray diffraction. Extensive 'cyclic' hydrogen bonds were formed among the bases related by pseudo-2-fold symmetry. The bonding parameters suggested that the 8-hydroxyguanine base consists of a predominant 2-amino-6,8-dioxo isomer (diketo form) including some tautomers.
A formal total synthesis of (±)-deserpidine (1) was accomplished by preparing the known synthetic precursors, two hydroxyesters 19 and 20, via a route involving regioselective formation of the 18-methoxyenone 10a followed by regioselective C-acylation of the enone 10a.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
The conformation of tert ‐butyloxycarbonyl‐Tyr‐Gly‐Gly‐(4‐bromo)Phe‐Met‐OH, as a monoanionic derivative of Met‐enkephalin, was elucidated by X‐ray crystal analysis. The molecule took an extended conformation which was bended at the Phe residue. The implication of the dimer formation caused by 4 intermolecular hydrogen bonds was discussed in the relation with the opiate receptor.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
