13 October 2008

Enzymes vs. Metal Catalysts

Mushroom enzyme could strip pollutants from fuel cells

This had to come up sooner or later.

They have demonstrated that laccase, an enzyme produced by fungi that grow on rotting wood, can be used as a cheaper and more efficient catalyst. Fuel cells use chemical reactions — such as that between hydrogen and oxygen — to produce emissions-free electricity. But current technology is expensive and requires electrodes that contain rare metals such as platinum.

When we talk about sustainable technology, one of the things that often gets over looked is the metals. Especially the heavy, toxic, and rare ones. And especially the ones mined in terrible conditions in poorer nations. We really don't like to think about the way our lovely technologies are dependent upon plundering the natural resources of other nations.

Scientists and entrepreneurs have come up with ways to replace the oil used in energy and the oil used in making some plastics with other things. So this step of replacing metal catalysts with biological enzymes was bound to start happening.

Materials that can hold the enzymes, such as carbon, are cheap and plentiful. But the second problem could prove a more difficult problem to crack. "This has puzzled scientists for decades, why are enzymes so large?" said Fraser Armstrong, a professor of chemistry at Oxford University. "There are a lot of people trying to work out how to make small molecules do the same thing. If you could do that, you could put a thousand times more enzymes on a surface."

This is where it pays to try to figure out the shape of the enzyme and the way the active site works. There is probably a large portion of any given enzyme that goes towards putting it in it's proper place in the cell, and interacting with other proteins, that wouldn't be needed in a fuel cell. The key is to take away the parts you don't need, keep the parts you do and then get the cell to produce this new stripped down protein in high concentrations. That takes some serious protein analysis and genetic modification. This biotechnology is decades out. But its being thought about and worked on, that's the first step.

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