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The critical main‐chain length for helix formation in water: Determined in a peptide series with alternating Aib and Ala residues exclusively and detected with ECD spectroscopy
Author(s) -
Longo Edoardo,
Moretto Alessandro,
Formaggio Fernando,
Toniolo Claudio
Publication year - 2011
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20986
Subject(s) - chemistry , circular dichroism , dimer , aqueous solution , peptide , helix (gastropod) , moiety , crystallography , oligopeptide , chirality (physics) , stereochemistry , organic chemistry , chiral symmetry , biochemistry , ecology , nambu–jona lasinio model , physics , quantum mechanics , snail , biology , quark
Critical main‐chain length for peptide helix formation in the crystal (solid) state and in organic solvents has been already reported. In this short communication, we describe our results aiming at assessing the aforementioned parameter in water solution. To this goal, we synthesized step‐by‐step by solution procedures a complete series of N‐terminally acetylated, C‐terminally methoxylated oligopeptides, characterized only by alternating Aib and Ala residues, from the dimer to the nonamer level. All these compounds were investigated by electronic circular dichroism in the far‐UV region in water solution as a function of chemical structure, namely presence/absence of an ester moiety or a negative charge at the C‐terminus, and temperature. We find that the critical main‐chain lengths for 3 10 ‐ and α‐helices, although still formed to a limited extent, in aqueous solution are six and eight residues, respectively. Chirality, 2011. © 2011 Wiley‐Liss, Inc.