作者:Magnus Rueping、Jürg V. Schreiber、Gérald Lelais、Bernhard Jaun、Dieter Seebach
DOI:10.1002/1522-2675(200209)85:9<2577::aid-hlca2577>3.0.co;2-d
日期:2002.9
The structural properties of four mixed beta-peptides with alternating beta(2)/beta(3) or beta(3)/beta(2)-sequences have been analyzed by two-dimensional homonuclear H-1-NMR- and CD spectroscopic measurements. All four beta-peptides fold into (P)-helices with twelve- and ten-membered H-bonded rings (Figs. 3-6). CD Spectra (Fig. 2) of the mixed beta(3)/beta(2)-hexapeptide 4a and beta(3)/beta(2)-nonapeptide 5a, indicating that peptides of this type also adopt the 12/10-helical conformation, were confirmed by NMR structural analysis. For the deprotected beta(3)/beta(2)-nonapeptide 5d, NOES not consistent with the 10/12 helix have been observed, showing that the stability of the helix decreases upon N-terminal deprotection. From the NMR structures obtained, an idealized helical-wheel representation was generated (Fig. 7), which will be used for the design of further 12/10 or 10/12 helices.