Scientists rev up speed of bionic enzyme reactions

Bionic enzymes got a needed boost in speed thanks to new research at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab). By pairing a noble metal with a natural enzyme, scientists created a hybrid capable of churning out 2,550 product molecules per hour, a frequency comparable to biological counterparts. 

The development, to be published in the Oct. 7 issue of the journal Science, represents a major advance for artificial metalloenzymes, which promise to open up a world of beneficial molecular products not currently possible with natural enzymes.

"Our work shows that artificial metalloenzymes can be practical and not just a cool curiosity," said study principal investigator John Hartwig, senior faculty scientist at Berkeley Lab's Chemical Sciences Division.

Earlier this year, Hartwig and his lab published a study in which they replaced the iron in the muscle protein myoglobin with iridium, a noble metal not found in living organisms. They demonstrated that the resulting hybrid is an enzyme that catalyzes a chemical reaction that no natural enzyme catalyzes.

The researchers chose myoglobin for that study because it is a well-studied protein that is easy to manipulate. It was an important proof of concept, but a key drawback was the new bionic enzyme's relatively slow reaction speed, which was about one-one thousandth the speed of typical natural enzymes.

"The artificial metalloenzymes we created made reactions occur faster than if the enzymes weren't there at all, but the rates were still much slower than those of natural enzymes," said Hartwig, who also holds an appointment as a UC Berkeley professor of chemistry.

As the need for speed is key in enzymatic reactions, the researchers switched the biological component from myoglobin to CYP119, part of a family of common enzymes called cytochrome P450, or CYPs.