INFLUENCE OF THE NATURE OF THE AROMATIC SIDE-CHAIN ON THE CONDUCTANCEOF THE CHANNEL OF LINEAR GRAMICIDIN - STUDY OF A SERIES OF 9,11,13,15-TYR(O-PROTECTED) DERIVATIVES

This paper describes the single channel properties of a series of synt hetic analogues of gramicidin A, where all four tryptophans are replac ed either by tyrosine or by several O-protected (benzyl, methyl, ethyl or t-butyl) derivatives. It is shown that, although all analogues bea r similar dipole moment on their side-chains, the conductance depends on the hydrophobicity of these protecting groups. An analysis of the c onductance data suggests that the conductance is governed by the bindi ng process and a possible explanation, based on conformational conside rations, is proposed.