Antiparallel β-sheet conformation in cyclopeptides containing a pseudo-amino acid with a biphenyl moiety
The biphenyl-containing pseudo-amino acids 2'-(aminomethyl)biphenyl-2-carboxylic acid (Abc; 1) and 2'-(aminomethyl)biphenyl-2-acetic acid (Aba; 2) are used as rigid spacers in the backbone of the cyclic peptides cyclo (-Abc-Ala-Phe-Gly-)2 (5),