Functionalized analogues of an unnatural amino acid that mimics a tripeptide beta-strand

This paper introduces polar and hydrophobic variants of the unnatural amino acid Hao, which mimics the hydrogen-bonding functionality of one edge of a beta-strand. In these variants, the methyl side chain of Hao is replaced with acidic, basic, and hydrophobic groups. These modifications can impart improved solubility and additional side-chain interactions to peptides containing Hao.