Helical versus Planar Conformation of Homooligopeptides Prepared from Diethylglycine (=2-Amino-2-ethylbutanoic Acid)

✍ Scribed by Masakazu Tanaka; Naoto Imawaka; Masaaki Kurihara; Hiroshi Suemune

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: German
• Weight: 293 KB
• Volume: 82
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/(sici)1522-2675(19990407)82:4<494::aid-hlca494>3.0.co;2-a

✦ Synopsis

Homooligopeptides containing a,a-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 C5-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 C5 structure.

Scheme