Formation of an extremely stable polyalanine beta-sheet macromolecule.

We have designed a 16-mer peptide composed of a stretch of alanine residues (Ac-KA14K-NH2) which is an effective, simple model for the study of beta-sheet formation in the hydrophobic cores of proteins. This peptide adopts an aqueous soluble "bundling" macromolecular beta-sheet structure, which is extremely stable to a wide range of pHs, temperatures and/or denaturants. Its unusual stability appears to be due to tight hydrophobic packing of the alanine residues in multilayer sheets or micellar forms with the multimeric lysine array being directed outward at the aqueous environment, allowing aqueous solubility.