Scientists have just created a working artificial enzyme. The enzyme was improved through a process called directed evolution. This technique could be used to develop enzymes capable of producing novel chemical products that aren’t synthesized in nature. The details are in a paper just published in the journal Nature.
Enzymes are proteins that catalyze (speed up) chemical reactions. The development of artificial enzymes could allow for easy production of rare and expensive chemicals. Metalloenzymes, enzymes that contain metal ions, are especially useful but difficult to create in the lab. Part of the problem is that these organometallic catalysts don’t work properly in cellular environments. Organometallic catalysts are used in industrial operations but fail to react correctly in living cells.
A team of researchers took a multi-step approach to creating a working metalloenzyme. First, they took advantage of the natural properties of the protein streptavidin. Streptavidin proteins have a high affinity for the vitamin biotin. The team was able to introduce an organometallic compound, containing the metal ruthenium, to streptavidin proteins by attaching it to biotin molecules. This allowed for the creation of an artificial metalloenzyme, called biot-Ru-SAV.
The team still had another problem to address, however. Metalloenzymes don’t work properly outside of industrial environments. The researchers had the idea to use the periplasm of Escherichia coli bacteria. The cellular environment of the periplasm was well-suited for the reactions due to the presence of low concentrations of metalloenzyme inhibitors.
The research team further refined their new metalloenzyme by using a technique called directed evolution. Directed evolution mimics natural selection to create more efficient proteins. By using directed evolution, the team could test different variants of biot-Ru-SAV and find the best ones. The improved version of biot-Ru-SAV worked; the enzyme catalyzed an olefin metathesis reaction. This type of reaction produces a fluorescent molecule, allowing researchers to quickly quantify the success of the experiment.
The team was able to create an artificial metalloenzyme not seen in nature, biot-Ru-SAV. The techniques used in the study can be applied to the development of other enzymes. The findings have important implications for biotechnology since artificial enzymes can be used to create novel products. Synthetic enzymes can produce chemicals that are currently rare or expensive.
Markus Jeschek et al. Directed evolution of artificial metalloenzymes for in vivo metathesis. Nature (2016).