tailieunhanh - Báo cáo khoa học: Structural function of C-terminal amidation of endomorphin Conformational comparison ofl-selective endomorphin-2 with its C-terminal free acid, studied by 1 H-NMR spectroscopy, molecular calculation, and X-ray crystallography

To investigate the structural function of the C-terminal amide group of endomorphin-2 (EM2, H-Tyr-Pro-Phe-Phe-NH2), an endogenous l-opioid receptor ligand, the solution conformations of EM2 and its C-terminal free acid (EM2OH, H-Tyr-Pro-Phe-Phe-OH) in TFE (trifluoroethanol), water (pH and ), and aqueous DPC (dodecylphosphocholine) micelles (pH and ) were investigated by the combination of 2D 1 H-NMR meas-urement and molecular modelling calculation. | ềFEBS Journal Structural function of C-terminal amidation of endomorphin Conformational comparison of 1-selective endomorphin-2 with its C-terminal free acid studied by 1H-NMR spectroscopy molecular calculation and X-ray crystallography Yasuko In1 Katsuhiko Minoura1 Koji Tomoo1 Yusuke Sasaki2 Lawrence H. Lazarus3 Yoshio Okada4 and Toshimasa Ishida1 1 Osaka University of PharmaceuticalSciences Takatsuki Osaka Japan 2 Department of Biochemistry Tohoku PharmaceuticalUniversity Sendai Japan 3 MedicinalChemistry Group Laboratory of Pharmacology and Chemistry NationalInstitute of EnvironmentalHealth Sciences Research Triangle Park NC USA 4 Faculty of PharmaceuticalSciences Kobe Gakuin University Kobe Japan Keywords endomorphin-2 C-terminal-deaminated endomorphin-2 NMR molecular calculation X-ray crystal analysis Correspondence Y. In Osaka University of Pharmaceutical Sciences 4-20-1 Nasahara Takatsuki Osaka 569-1094 Japan Fax 81 72 690 1068 Tel 81 72 690 1069 E-mail in@ Received 30 June 2005 revised 8 August 2005 accepted 16 August 2005 doi To investigate the structural function of the C-terminal amide group of endomorphin-2 EM2 H-Tyr-Pro-Phe-Phe-NH2 an endogenous p-opioid receptor ligand the solution conformations of EM2 and its C-terminal free acid EM2OH H-Tyr-Pro-Phe-Phe-OH in TFE trifluoroethanol water pH and and aqueous DPC dodecylphosphocholine micelles pH and were investigated by the combination of 2D 1H-NMR measurement and molecular modelling calculation. Both peptides were in equilibrium between the cis and trans rotamers around the Tyr-Pro w bond with population ratios of 1 1 to 1 2 in dimethyl sulfoxide TFE and water whereas they predominantly took the trans rotamer in DPC micelle except in EM2OH at pH which had a trans cis rotamer ratio of 2 1. Fifty possible 3D conformers were generated for each peptide taking different electronic states depending on the type of solvent and pH neutral and .