Watch the steps involved in directed evolution in the lab. In New Zealand, directed evolution is being used to make new enzymes to help treat cancer.
Polymerase chain reaction or PCR is used to make multiple copies of a gene.
Normally, PCR makes exact copies of a gene, but by using ‘sloppy’ forms of PCR, scientists can introduce random changes in the gene’s DNA sequence. Millions of gene variants are made this way.
A gene variant is inserted into a plasmid and translated into the evolved enzyme in a bacterial cell.
Each gene variant will produce a slightly different evolved enzyme. Some of these enzymes may be better at catalysing a particular reaction than others.
Scientists then use a screening test to determine which evolved enzyme is best at catalysing the reaction. Sometimes, the product of that reaction can be measured directly. Alternatively, a reporter gene, which produces a coloured product, is used to measure the reaction.
The evolved enzyme that is best at catalysing the desired reaction may be used in medicine or industry.