Longer-lived proteins

摘要

The past 25 years have seen an explosion in the number of approved protein drugs produced by genetic engineering, for treating hormonal, metabolic, immu-nological, haematological and reproductive disorders, as well as cancer1. Scientists initially sought to perfectly copy nature's structural expression of these proteins, leading to many first-generation drugs. Subsequently, protein engineers began to adapt natures structures, either subtly (for example, by changing a few amino-acid residues to make interactions with a target molecule stronger or more specific) or more profoundly (for instance, by attaching two unrelated proteins to create a protein possessing a combined function that nature never considered). Several second-generation drugs have resulted from such efforts.