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Formation of Periodic γ ‐Turns in α / β ‐Hybrid Peptides: DFT and NMR Experimental Evidence
Author(s) -
Chandrasekhar Srivari,
Rao Kakita Veera Mohana,
Seenaiah Mallikanti,
Naresh Police,
Devi Ambure Sharada,
Jagadeesh Bharatam
Publication year - 2014
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201301068
Subject(s) - hydrogen bond , chemistry , folding (dsp implementation) , amino acid , stereochemistry , side chain , polar , protein secondary structure , structural motif , molecular dynamics , crystallography , molecule , computational chemistry , organic chemistry , biochemistry , physics , astronomy , electrical engineering , engineering , polymer
Hybrid peptidic oligomers comprising natural and unnatural amino acid residues that can exhibit biomolecular folding and hydrogen‐bonding mimicry have attracted considerable interest in recent years. While a variety of hybrid peptidic helices have been reported in the literature, other secondary structural patterns such as γ ‐turns and ribbons have not been well explored so far. The present work reports the design of novel periodic γ ‐turns in the oligomers of 1:1 natural‐ α /unnatural trans‐β ‐norborenene (TNAA) amino acid residues. Through DFT, NMR, and MD studies, it is convincingly shown that, in the mixed conformational pool, the heterogeneous backbone of the hybrid peptides preferentially adopt periodic 8‐membered (pseudo γ ‐turn)/7‐membered (inverse γ ‐turn) hydrogen bonds in both polar and non‐polar solvent media. It is observed that the stereochemistry and local conformational preference of the β‐amino acid building blocks have a profound influence on accessing the specific secondary fold. These findings may be of significant relevance for the development of molecular scaffolds that facilitate desired positioning of functional side‐chains.