Open AccessN ‐( tert ‐Butoxycarbonyl)‐ L ‐valyl‐ L ‐valine methyl ester: a twisted parallel β‐sheet in the crystal structure of a protected dipeptide
Author(s) -
Jacobsen Øyvind,
Gebreslasie Hadgu Girmay,
Klaveness Jo,
Rongved Pål,
Görbitz Carl Henrik
Publication year - 2011
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
eISSN - 1600-5759
pISSN - 0108-2701
DOI - 10.1107/s0108270111022293
Subject(s) - polyproline helix , dipeptide , hydrogen bond , molecule , stereochemistry , chemistry , crystallography , helix (gastropod) , peptide , organic chemistry , biochemistry , ecology , snail , biology
The title compound, C 16 H 30 N 2 O 5 , crystallizes with three molecules in the asymmetric unit, each adopting a β‐strand/polyproline II backbone conformation. The main‐chain functional groups are hydrogen bonded into tapes having the characteristics of parallel β‐sheets. Each tape has a left‐handed twist and thus forms a helix, with six peptide molecules needed to complete a full 360° rotation. A comparison of hydrogen‐bond lengths and twisting modes is made with other related structures of protected dipeptides and with a hexapeptide derived from amyloid‐β containing the Val–Val segment. Additionally, a comparison of the backbone conformation is made with that of the Val141–Val142 segment of the water channel aquaporin‐4 (AQP4).