2. The "directed" evolution of proteins and peptides

It is therefore not currently possible to design proteins with new and useful functions, because while we know how to produce any protein, we don't yet know how to "calculate" the protein sequence that will give the precise spatial conformation needed for the protein to perform that function. Nevertheless, a range of approaches grouped under the umbrella term "directed protein evolution" have been developed to circumvent this problem, and have proved highly effective in creating proteins with new or improved capabilities. These proteins with novel properties were obtained by directed evolution when no other method would have enabled them to be designed or calculated.

The general idea behind this approach is to artificially reconstitute in the laboratory a "Darwinian" process that mimics the evolutionary process at the origin of all natural proteins. These have appeared...