Peptides are among the more significant messengers in the body. But they don't make good oral drugs because they're digested in the stomach.
Peptides are chains of amino acids.
They activate cells by interacting with cell-surface proteins called receptors. A receptor recognizes a particular peptide by its shape, as a lock recognizes a key. Many peptides assume the optimal shape for biological activity by putting a U-turn into their amino acid backbone. In 1967, Marshall began to create and manipulate virtual models of molecules, opening up an entirely new field. He now will use the software he has developed to design organic molecules with 180 degree reverse turns.