... of endomorphin Conformational comparison of l-selective endomorphin- 2 with its C-terminal free acid, studied by 1 H-NMR spectroscopy, molecular calculation, and X-ray crystallography Yasuko In 1 , Katsuhiko Minoura 1 , ... bondsN (1) A O(4ÂÂ)A 2.728(5) 1. 85 15 4 x,y,zN (1) A O(4W) 2.848(5) 1. 97 15 5 x +1, y,zN (1) A O(7W) 2.754(5) 1. 91 154 x +1, y,zO(1H)A O(4ÂÂ)B 2.598(5) 1. 66 15 7 1- x,y +1 ⁄ 2,-zN(3)A O(2W) 2.899(5) 2 .13 14 6 ... 13 9 x,y,zO(1W) O (1 )A 2.773(4) 1. 76 16 7 x,y +1, zO(1W) O(3 W) 2.8 71( 4) 1. 98 14 8 x,y +1, zO(2W) O(3Â)A 2.756(5) 1. 82 16 7 x,y -1, zO(2W) O(1W) 2.822(4) 1. 94 17 3 x,y -1, zO(3W) O(4ÂÂ)A 2.682(5) 1. 86...