Premium
Mixed β 2 / β 3 ‐Hexapeptides and β 2 / β 3 ‐Nonapeptides Folding to ( P )‐Helices with Alternating Twelve‐ and Ten‐Membered Hydrogen‐Bonded Rings
Author(s) -
Rueping Magnus,
Schreiber Jürg V.,
Lelais Gérald,
Jaun Bernhard,
Seebach Dieter
Publication year - 2002
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(200209)85:9<2577::aid-hlca2577>3.0.co;2-d
Subject(s) - chemistry , homonuclear molecule , helix (gastropod) , crystallography , stereochemistry , nuclear magnetic resonance spectroscopy , molecule , ecology , organic chemistry , snail , biology
The structural properties of four mixed β ‐peptides with alternating β 2 / β 3 ‐ or β 3 / β 2 ‐sequences have been analyzed by two‐dimensional homonuclear 1 H‐NMR‐ and CD spectroscopic measurements. All four β ‐peptides fold into ( P )‐helices with twelve‐ and ten‐membered H‐bonded rings ( Figs. 3–6 ). CD Spectra ( Fig. 2 ) of the mixed β 3 / β 2 ‐hexapeptide 4a and β 3 / β 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 β 3 / β 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.