TOAC: a useful Cα-tetrasubstituted α-amino acid for peptide conformational analysis by CD spectroscopy in the visible region. Part I

Doubly labelled 4-amino-4-carboxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TOAC)-containing trichogin analogues showed a correlation between the CD intensity of the TOAC transition and their conformation. The helical-inducing property of the TOAC residue is position dependent and, apart from the N-terminal position, better than that of...