Enzymes are the protein molecules that accelerate chemical reactions in all types of cells. Most enzymes are designed for specific functions, for example certain enzymes will break down antibiotics resulting in antibiotic resistance. This specialisation suggests a lack of flexibility but we know that enzymes do develop novel functions, so how does this happen? If enzymes are designed for one role, how do they develop novel functions?

Whilst doing her PhD, Valerie Soo discovered that many enzymes in the laboratory bacterium, Escherichia coli, have weak secondary functions. When placed in environments where toxins
or antibiotics were present, these secondary functions enabled the bacteria to grow in almost one third of these environments. The unexpected development of antibiotic resistance shows the possible role of weak secondary functions and how they help to evolve new functions in proteins.