Study on the spatial structure of brachystemin C, a new cyclic peptide from Brachystemma calycinum

• DOI: 10.1016/j.molstruc.2003.09.012
• Publication Date: 2003-11-20T13:03:07Z
• Authors: Cheng Wang; Li-Li Zhang; Yang Lu; Qi-Tai Zheng; Yong-Xian Cheng; Jun Zhou; Ning-Hua Tan
• Keywords: 01 natural sciences; 0104 chemical sciences

A new cyclic octapeptide, brachstemin C (the molecular formula: C38H56N8O9), was isolated from the root of Brachystemma calycinum. The types and sequence of the amino acids of the title compound were confirmed by spectral analyses and X-ray diffraction. The stereochemistry of the title cyclic octapeptide was clarified by X-ray crystallographic study. The cyclic octapeptide backbone contains three beta-turns. Two of them are type I beta-turns and one is type III beta-turn (right-handed 3(10) helix). There are intermolecular hydrogen bonds between the cyclic peptide and the solvent molecules which maintained the steady spatial arrangement in crystal. (C) 2003 Elsevier B.V. All rights reserved.