1246024-70-3Relevant academic research and scientific papers
Helical Oligopeptides of a Quaternized Amino Acid with Tunable Chiral-Induction Ability and an Anomalous pH Response
Cho, Joonil,Ishida, Yasuhiro,Aida, Takuzo
supporting information, p. 4818 - 4826 (2017/04/14)
A series of octamer (8-mer) and hexadecamer (16-mer) oligopeptides of 4-aminopiperidine-4-carboxylic acid (Api) with l-leucine as a chiral auxiliary at their N or C termini were synthesized. By using circular dichroism spectroscopy, the conformational profiles of the peptides were systematically studied, which revealed that the α-helix-formation ability of the peptides is determined by the combination of parameters, which includes peptide length, state of the piperidine groups in the Api units, and position of the chiral auxiliary. When the piperidines were in the free-base state, the peptides showed a low propensity to form helical structures. However, the protonation and acylation of the piperidines enhanced the formation of helical structures, such that the order for helix-formation ability was protonated>acylated>free base. In terms of peptide length, the 16-mers generally showed higher helix-formation ability than the corresponding 8-mers, and one of the 16-mers showed helicity at the highest level reported thus far for oligopeptides of a similar length. It was also found that the sensitivity of the helical structure towards the state of the piperidine groups changed drastically depending on the chiral auxiliary position; the N-terminal chiral peptides were more sensitive than the C-terminal chiral analogues.
Oligo(4-aminopiperidine-4-carboxylic acid): An unusual basic oligopeptide with an acid-induced helical conformation
Cho, Joon-Il,Tanaka, Masahiro,Sato, Sota,Kinbara, Kazushi,Aida, Takuzo
supporting information; experimental part, p. 13176 - 13178 (2010/12/19)
In sharp contrast with helical polypeptides carrying basic side chains, Api8, 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 Api8 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 Api8, 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.
