Three‐Residue Turn in β‐Peptides Nucleated by a 12/10 Helix |
| |
Authors: | Dr Gangavaram V M Sharma Thota Anupama Yadav Kanakaraju Marumudi Prashanth Thodupunuri Pothula Purushotham Reddy Dr Ajit C Kunwar |
| |
Institution: | 1. Organic and Biomolecular Chemistry Division, CSIR‐Indian Institute of Chemical Technology, Hyderabad 500 007 (India), Fax: (+91)?40‐27160387/27193108;2. Centre for NMR and Structural Chemistry, CSIR‐Indian Institute of Chemical Technology, Hyderabad 500 007 (India) |
| |
Abstract: | A new three‐residue turn in β peptides nucleated by a 12/10‐mixed helix is presented. In this design, β peptides were derived from the 1:1 alternation of C‐linked carbo‐β‐amino acid ester BocNH‐(R)‐β‐Caa(r)‐OMe] (Boc=tert‐butyloxycarbonyl), which consisted of a D ‐ribo furanoside side chain, and β‐hGly residues. The hexapeptide with (R)‐β‐Caa(r) at the N terminus showed the ‘turn’ stabilized by a 14‐membered NH(4) ??? CO(6) hydrogen bond at the C terminus nucleated by a robust 12/10‐mixed helix, thus providing a ‘helix‐turn’ (HT) motif. The turn and the helix were additionally stabilized by intraresidue electrostatic interaction between the furan oxygen in the carbohydrate side chain and NH in the backbone. However, the hexapeptide with a β‐hGly residue at the N terminus demonstrated the presence of a 10/12 helix through its entire length, which again showed the intraresidue interaction between NH and furan oxygen. The intraresidue NH ??? O? Me electrostatic interactions observed in the monomer, however, were absent in the peptides. |
| |
Keywords: | electrostatic interactions foldamers helical structures hydrogen bonds peptides |
|
|