Heparin Mimic Shields Protein Therapeutic

To protect protein drugs from decomposing in the body, manufacturers frequently modify them with chemical groups such as polyethylene glycol. But the added groups don’t always protect proteins from conditions such as high temperature and low pH. To address this shortcoming, a UCLA research team has designed a new protective group—a polymer arm that mimics the anti-blood-clotting molecule heparin (Nat. Chem., DOI: 10.1038/nchem.1573). The researchers conjugated the new group to a heparin-binding protein called basic fibroblast growth factor (bFGF) via disulfide exchange. When heated to 55 °C for 30 minutes, added to an acidic solution (pH 4.7) for 16 hours, or exposed to a protein-cleaving enzyme called trypsin for 16 hours, the bFGF-polymer conjugate remained intact and active: bFGF was still able to aid in the growth of human skin cells. “The conjugate has the biological activity of native bFGF,” explains team leader Heather D. Maynard. “But unlike bFGF, it doesn’t need to be stored in the freezer before use or used at very high concentrations. These factors are inconvenient for doctors and patients and can increase costs.” Maynard adds that her team is now collaborating with dermatologists to test the wound-healing capabilities of the conjugate.