Impact of Peptide Length and Solution Conditions on Tetrameric Coiled Coil Formation.

Unlike naturally derived peptides, computationally designed sequences offer programmed self-assembly and charge display. Herein, new tetrameric, coiled coil-forming peptides were computationally designed ranging from 8 to 29 amino acids in length. Experimental investigations revealed that only the sequences having three or more heptads (i.e., 21 or more amino acids) exhibited coiled coil behavior. The shortest stable coiled coil sequence had a melting temperature () of approximately 58 ± 1 °C, making it ideal for thermoreversible assembly over moderate temperatures. Effects of pH and monovalent salt were examined, revealing structural stability over a pH range of 4 to 11 and an enhancement in with the addition of salt. The incorporation of the coiled coil as a hydrogel cross-linker results in a thermally and mechanically reversible hydrogel. A subsequent demonstration of the hydrogel printed through a syringe illustrated one of many potential uses from 3D printing to injectable hydrogel drug delivery.