Peptide constraints and unnatural amino acids can suppress proteolysis. The L/R constrained peptide exhibited increased resistance to both trypsin (cleavage at positively charged residues) and α-chymotrypsin (cleavage at aromatic and hydrophobic aliphatic residues) whilst the S/E constrained variant was not protected in comparison to the WT sequence, but did exhibit a change in cleavage site (Fig. ).