Oligo(4-aminopiperidine-4-carboxylic acid): an unusual basic oligopeptide with an acid-induced helical conformation.
In sharp contrast with helical polypeptides carrying basic side chains, Api(8), a basic oligopeptide containing the non-natural achiral amino acid 4-aminopiperidine-4-carboxylic acid (Api), adopts a helical conformation only in acidic media. Alkaline titration of a protonated Api(8) oligomer appended with a leucine derivative at its N-terminus showed that disruption of its helical conformation occurs in a pH range of 7-10. NMR studies indicated that the piperidine groups in Api(8), when nonprotonated, possibly interact with the proximal amide protons in the peptide backbone and hamper the formation of the H-bonding network responsible for the helical conformation. The helical structure is induced not only by protonation but also by acylation of the piperidine groups.
Cho
Joon-il
JI
Department of Chemistry and Biotechnology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Tanaka
Masahiro
M
Sato
Sota
S
Kinbara
Kazushi
K
Aida
Takuzo
T
D009682:Magnetic Resonance Spectroscopy; D009842:Oligopeptides / Q000737:chemistry*; D010880:Piperidines / Q000737:chemistry*; D011487:Protein Conformation
C481395:4-aminopiperidine; D009842:Oligopeptides; D010880:Piperidines