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Peptide Helices as Rigid Molecular Rulers: A Conformational Study of Isotactic Homopeptides from α‐Methyl‐α‐isopropylglycine, [L‐(αMe)Val] n
Author(s) -
Polese Alessandra,
Formaggio Fernando,
Crisma Marco,
Valle Giovanni,
Toniolo Claudio,
Bonora Gian Maria,
Broxterman Quirinus B.,
Kamphuis Johan
Publication year - 1996
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.19960020911
Subject(s) - random hexamer , trimer , histone octamer , crystallography , helix (gastropod) , nuclear magnetic resonance spectroscopy , tacticity , chemistry , steric effects , stereochemistry , triple helix , spectroscopy , pentamer , peptide , circular dichroism , physics , polymerization , polymer , biology , dimer , ecology , biochemistry , organic chemistry , quantum mechanics , nucleosome , snail , histone , gene
Terminally blocked, isotactic homopeptides from the sterically demanding α‐methylvaline of general formula Y‐[L‐(αMe)Val] n ‐O t Bu (Y = Z, p BrBz, Ac; n = 2–8) have been prepared step‐by‐step in solution and fully characterized. The conformations preferred in solution (β‐turn and right‐handed 3 10 ‐helix) have been assessed by FT‐IR, 1 H NMR and CD spectroscopy. The molecular and crystal structures of the Z‐protected trimer, hexamer, heptamer and octamer have been determined by X‐ray diffraction. In the crystal state, while the trimer is folded in a type III β‐turn conformation, the longest homopeptides form well‐developed, regular, right‐handed 3 10 ‐helices. The screw sense in the helix of the p BrBz‐blocked octamer has been confirmed to be right‐handed by solid‐state and solution CD spectroscopy. The possible exploitation of these peptide helices as rigid and precise molecular rulers is discussed.