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Helical versus Planar Conformation of Homooligopeptides Prepared from Diethylglycine (=2‐Amino‐2‐ethylbutanoic Acid)
Author(s) -
Tanaka Masakazu,
Imawaka Naoto,
Kurihara Masaaki,
Suemune Hiroshi
Publication year - 1999
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/(sici)1522-2675(19990407)82:4<494::aid-hlca494>3.0.co;2-a
Subject(s) - chemistry , tripeptide , pentapeptide repeat , solid state , stereochemistry , crystallography , group (periodic table) , bent molecular geometry , amino acid , planar , oligopeptide , ethyl ester , peptide , organic chemistry , computer graphics (images) , computer science , biochemistry
Homooligopeptides containing α , α ‐diethylgycine (=2‐amino‐2‐ethylbutanoic acid), were synthesized by conventional solution methods. An ethyl or methyl ester was used as protecting group at the C‐terminus and a trifluoroacetyl group as protecting group at the N‐terminus of the peptides. The conformations of such tri‐, penta‐, and hexapeptides in the solid state were studied using X‐ray crystallographic analysis, and were shown to be a bent planar C 5‐conformation in the case of tripeptide 8a , and a 3 10 ‐helical structure in the case of pentapeptide 10 and hexapeptide 11 . IR and 1 H‐NMR spectra revealed that the dominant conformation of hexapeptide 11 in CDCl 3 solution was not the 3 10 ‐helical structure shown in the solid state, but a fully planar C 5 structure.