Many modern medicines, including insulin and some vaccines, are made from proteins — complex molecules that perform specific functions in the body. Proteins are delicate: If they stick together or break down, the medicine can become less effective. Scientists have long sought ways to keep these drugs stable during manufacturing, storage, and use.

Amino acids have been used as stabilizers for protein-based therapies, but there was no general understanding of how they worked. Now, an international research team has reported new findings that could guide their use and improve the longevity and effectiveness of some pharmaceuticals. For example, adding the amino acid proline to insulin makes it twice as effective in the bloodstream, meaning diabetics could need fewer doses.

To understand these results, the researchers developed a general theory explaining how amino acids stabilize proteins. The open-access findings were reported recently in the journal Nature, by a team of researchers at MIT, École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, and the Southern University of Science and Technology in China.