Conformation switchable antimicrobial peptides and methods of using the same

An antimicrobial polypeptide comprising Formula I:

• wherein
• m is 3 to about 50;
• n is 5 to about 100;
• p is 0 or 10;
• q is 0, 1, 2, or 3;
• R* is H or a negative charge;
• Q is —C(═O)O—, —C(═O)NH—, —NH—C(═O)—, or a direct bond;
• L is a carbon-containing linker of at least two atoms in length;
• and
• X is primary amine, a secondary amine, a tertiary amine, or a quaternary ammonium moiety;
• wherein the polypeptide adopts a random coil confirmation in solution at a pH of greater than about 6.5, and the polypeptide adopts a helical confirmation in solution at a pH of less than about 3.5.