UPTON, NY-Scientists studying an enzyme that naturally produces alkanes -- long carbon-chain molecules that could be a direct replacement for the hydrocarbons in gasoline -- have figured out why the natural reaction typically stops after three to five cycles. Armed with that knowledge, they've devised a strategy to keep the reaction going. The biochemical details -- worked out at the U.S. Department of Energy's Brookhaven National Laboratory and described in the Proceedings of the National Academy of Sciences the week of February 4, 2013 -- renew interest in using the enzyme in bacteria, algae, or plants to produce biofuels that need no further processing.
"Alkanes are very similar to the carbon-chain molecules in gasoline. They represent a potential renewable alternative to replace the petrochemical component of gasoline," said Brookhaven biochemist John Shanklin, who led the research, which was conducted in large part by former Brookhaven postdoc Carl Andre, now working at BASF Plant Science in North Carolina, and Xiaohong Yu of Brookhaven's Biosciences Department. "Unlike the process of breaking down plant biomass to sugars and fermenting them to ethanol," Shanklin said, "biologically produced alkanes could be extracted and used directly as fuel."
Recent discovery of an enzyme known as aldehyde-deformylating oxygenase (ADO), which naturally makes alkanes from precursors in certain bacteria, stimulated interest in harnessing this enzyme's action to make liquid biofuels. But early attempts to install ADO in laboratory-based alkane "factories" produced disappointing results.
Likewise, the Brookhaven team's experiments in test tubes-using substrates synthesized with the help of Sunny Kim in Brookhaven's Radiotracer and Biological Imaging group-yielded the same result others had observed: The enzyme mysteriously stopped working after three to five "turnovers" and alkane production would cease.
Biochemical curiosity and A
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DOE/Brookhaven National Laboratory