Killian J A, Timmermans J W, Keur S, de Kruijff B
Biochim Biophys Acta. 1985 Oct 24;820(1):154-6. doi: 10.1016/0005-2736(85)90227-5.
It is shown that N-formylation of the tryptophan residues of gramicidin completely and reversibly blocks the hexagonal HII phase-inducing ability of the peptide in dioleoylphosphatidylcholine model membranes.