Non-hydrogen-bonded secondary structure in beta-peptides: evidence from circular dichroism of (S)-pyrrolidine-3-carboxylic acid oligomers and (S)-nipecotic acid oligomers.
[formula: see text] Homooligomers of beta-amino acids (S)-3-pyrrolidine-3-carboxylic acid (PCA) and (S)-nipecotic acid (Nip) were studied by circular dichroism (CD) in methanol. In each series, a profound change in the far-UV CD spectrum was observed from monomer to tetramer, but little change was observed from tetramer to hexamer. A comparable pattern is observed in the CD spectra of short proline oligomers. We conclude that both PCA and Nip oligomers with > or = four residues adopt a characteristic secondary structure.
Huck
B R
BR
Department of Chemistry, University of Wisconsin, Madison 53706, USA.
Langenhan
J M
JM
Gellman
S H
SH
D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D009557:Nipecotic Acids / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D011392:Proline / Q000031:analogs & derivatives* / Q000737:chemistry; D017433:Protein Structure, Secondary; D011759:Pyrrolidines / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet
D009557:Nipecotic Acids; D010455:Peptides; D011759:Pyrrolidines; C410686:pyrrolidine-3-carboxylic acid; C030278:nipecotic acid; D011392:Proline; C010983:homoproline; C072401:beta-proline