by Heather Lammers (National Renewable Energy Laboratory/Renewable Energy World Magazine) Thanks to newer and faster supercomputers, today’s computer simulations are opening hidden vistas to researchers in all areas of science. These powerful machines are used for everything from understanding how proteins work to answering questions about how galaxies began. Sometimes the data they create manage to surprise the very researchers staring back at the computer screen—that’s what recently happened to a researcher at the Energy Department’s National Renewable Energy Laboratory (NREL).
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Working Together in Ways We Don’t Understand
The enzymes that the NREL researchers are examining have several different components that work together to break down biomass. The enzymes have a catalytic domain — which is the primary part of the enzyme that breaks down the material into the needed sugars. There is also a binding module, the sticky part that attaches the cellulose to the catalytic domain. The catalytic domain and the binding module are connected to each other by a linker.
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Cellulose is a long linear chain of glucose that makes up the main part of plant cell walls, but the bonds between the glucose molecules make it very tough to break apart. In fact, cellulose in fossilized leaves can remain intact for millions of years, but enzymes have evolved to break down this biomass into sugars by threading a single strand of cellulose up into the enzymes’ catalytic domain and cleaving the bonds that connect glucose molecules together. Scientists are interested in the enzymes in fungi like Trichoderma reeseibecause they are quite effective at breaking down biomass — and fungi can make a lot of protein, which is also important for biomass conversion.
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Seeing Isn’t Always Believing
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The NREL research team experimentally verified the computational predictions by working with researchers at the University of Colorado Boulder (CU Boulder), Swedish University of Agricultural Sciences, and Ghent University in Belgium. Using proteins made and characterized by the international project team, NREL’s Michael Resch showed that by measuring the binding affinity of the binding module and then comparing it to the binding module with the linker added, the linker imparted an order of magnitude in binding affinity to cellulose…
According to Beckham, improving these enzymes is very challenging but incredibly important for cost-effective biofuels production, which the Energy Department has long recognized. READ MORE Abstract