Display of the enzyme section that controls the optimum temperature. The circled areas, shown in dark blue, are from Antarctic bacteria and those shown in red are from porcine enzymes. By introducing the mutation into the Antarctic structure, the loop can be moved towards the pig structure and the optimal temperature raised. Image/Johan Åqvist
For the first time, researchers have been able to predict how to change the optimum temperature of an enzyme using large computer calculations.
Cold-adapted enzymes from Antarctic bacteria are used as a basis. The study will be published in the journal Science Advances and is a collaboration between researchers at Uppsala University in Sweden and the University of Tromsø in Norway.
The kind of cold-adapted enzymes the researchers used for their studies can be found in bacteria and fish that live in ice water, for example. Evolution has molded them to function even at very low temperatures where other enzymes would normally shut down. These enzymes also always have lower optimal temperatures and melting points than enzymes from warm-blooded animals and organisms living at higher temperatures.
Optimum temperature rise
The researchers wondered whether computer simulations of the chemical reactions they catalyzed could predict the small number of mutations in Antarctic enzymes that could result in an increase in their optimum temperature. The calculation results show that this is possible if 16 mutations are introduced from the corresponding pig enzymes into the bacterial variant.
The researchers then generated this hybrid enzyme and measured its catalytic activity as a function of temperature, and found that the new variant had an optimum 6°C higher than the original variant and was faster than the Antarctic and porcine enzymes at 50°. C. They also solved the three-dimensional structure of the hybrid enzyme by X-ray crystallography and showed that the necessary structural changes predicted by computer calculations had occurred.
Computer-based enzyme design has become a major research area and has received great interest in recent years. The goal is to create enzymes with new properties and do it with the help of computer calculations instead of labor-intensive experiments.
“For example, this might involve creating new enzymes that catalyze chemical reactions not found in nature or changing their properties so they can better cope with heat, cold, high pressure, increased salinity, and so on. Therefore, this field is the subject of great biotechnology interest,” said Johan Aqvist, professor of Theoretical Chemistry at Uppsala University.