beta(2,2)-Aminoxy acids: a new building block for turns and helices.
The conformational properties of peptides 1-4 built from 3-aminoxy-2,2-dimethyl-propionic acid, a beta2,2-aminoxy acid, were investigated by NMR spectroscopy and X-ray crystallography. A novel beta N-O turn involving a nine-membered-ring intramolecular hydrogen bond between NHi+2 and COi was formed in diamides 1 and 2, which was further stabilized by another six-membered-ring intramolecular hydrogen bond between NHi+2 and NOi+1. Triamides 3 and 4 displayed a well-defined helical structure featuring two consecutive beta N-O turns. The X-ray structure of 4 revealed that the amide carbonyl group at position i+2 was twisted +65.9 degrees from that at i position, suggesting a novel 1.79 helix. Therefore, beta2,2-aminoxy acid can be used as a new building block for turns and helices.
Yang
Dan
D
Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong. yangdan@hku.hk
Zhang
Yu-Hui
YH
Zhu
Nian-Yong
NY
D000577:Amides / Q000138:chemical synthesis / Q000737:chemistry*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D011422:Propionates / Q000737:chemistry*; D017433:Protein Structure, Secondary
D000577:Amides; D010455:Peptides; D011422:Propionates