Mode of action of the gramicidin S analogs lacking hydrophilic amino acid residues on biomembranes.

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Abstract
The gramicidin S analog lacking basic ornithine residues, cyclo(-Val-Ala-Leu-.DELTA.Phe-Pro-)2 (where .DELTA.Phe represents .alpha.,.beta.-dehydrophenylalanine), increased the K+ permeability of human erythrocytes and Staphylococcus aureus similarly to the parent gramicidin S. This analog altered thenormal discoid shape of human erythrocytes to an invaginated form. The direction of the shape change was opposite to the case of gramicidin S causing crenated cells. We suppose that the analog accumulated predominantly into the inner half monolayer of membrane and destabilized the membrane structure, resulting in a break in the membrane.