Patent ID: 6991775

Claim:
A purified peptide comprising the amino acid sequence: P*-Y*-X 1 *-L* (SEQ ID NO:1), wherein: P* is a proline or its non-natural derivative 4-hydroxyproline; Y* is a tyrosine or its non-natural derivative substituted at the 3 position with a moiety selected from the group consisting of F, Cl, Br, I, and NO 2 ; provided that at least one of said P* or Y* is said non-natural derivative of the respective amino acid; X 1 * is G or a non-natural derivative of G selected from the group consisting of cyclohexylglycine, allylglycine, 2-indanylglycine, tert-butylglycine, N-(4-phenylbutyl)glycine, N-decylglycine, phenylglycine, propargylglycine, and the d isomer of glycine; or D or a non-natural derivative of D selected from the group consisting of β-connected aspartic acid (bD), N-methylaspartic acid, and the d isomer of aspartic acid; and L* is a leucine or a non-natural derivative of leucine selected from the group consisting of N-methylleucine, Norleucine, tert-leucine, and the d isomer of leucine.