Human integrin a5b6, a member of the integrin family, is specifically expressed in many malignancies but not in normal organs. Generation of integrin a5b6, specific binding moiety has been demonstrated potential clinical applications, such as specific human integrin a5b6, binding peptide P2: NAVPNLRGDLQVLAQKVART, which derived from foot-and-mouth disease virus was used as radiotracer for tumor image in vivo. Using flow cytometry and ELISA assay, this P2 peptide was demonstrated to have a highly selective, inhibiting a5b6-ligand binding with a IC50 of 3 nmol/L, an activity 1,000-fold more selective for a5b6 than for other RGD-directed integrins (avb3, avb5, and avb1).

A peptide of P2 NAVPNLRGDLQVLAQKVART was constructed with codon optimization gene synthesis and expressed with a human Alpha Fetal protein at N-terminal. This protein was expressed in E. coli as inclusion bodies. The final product was refolded using our unique “temperature shift inclusion body refolding” technology and chromatographically purified.