二蕊荷莲豆环肽B的NMR应用研究

植物环肽的¹H 和¹³C NMR图谱, 由于各种氨基酸自旋系统质子和碳的化学位移非常接近，谱峰高度重叠，结构解析比较困难. 文中以二蕊荷莲豆环肽B为例讨论了
现代2D NMR新技术，在植物环肽结构解析中的应用. HMQC-TOCSY图谱在氢谱方向和碳谱方向分别提供每一个氨基酸自旋系统内的氢和除季碳外碳的全相关信息，从而将每个氨基酸残基的NMR信号相互区分开来；结合¹H-¹H COSY 和 HMQC或HSQC图谱，就可以准确归属每个氨基酸的氢和碳的化学位移. 氨基酸残基之间的连接顺序可用HMBC、NOESY或ROESY图谱获得.

A NMR STUDY ON PLANT CYCLOPEPTIDE DRYMARIN B

Object Severe spectral overlap often occurs in the 1H and 13 C NMR spectra of plant cyclopeptides because of the similarity in chemical shifts of different amino acid residuals. This paper aims to look for suitable NMR techniques for structural elucidation of plant cyclopeptides. Methods 2D NMR techniques such as HMQC, HMBC, ROESY, and HMQC TOCSY were used to study the structure of Drymarin B, a cyclopeptide isolated from the plant \%Drymaria diandra\% B1 (Caryophyllaceae). Results The 1H and 13 C chemical shifts of the amino acid residuals (except for the quaternary carbons) can be assigned simultaneously using 2D HMQC TOCSY because this technique provides not only total proton correlation in the F 2 dimension but also total carbon correlation (except for the quaternary carbons) in the F 1 dimension. The linkages among the anino acid residuals can be determined by long range correlations from the HMBC spectra or NOEs from the ROESY or NOESY spectra. Conclusion The 2D NMR techniques are efficient tools for structural elucidation of plant cyclopeptides.