Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Enzyme Detectives Uncover New Reactions, Products: Implications for engineering biofuels and plant-derived replacements for petro-chemicals

Desaturation of Fatty Acids -- introducing a double bond turns bad fat into good fat.
Desaturation of Fatty Acids -- introducing a double bond turns bad fat into good fat.

Abstract:
If your experiment doesn't go the way you expect, take a closer look — something even more interesting may have happened. That strategy has led scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory to discover a fundamental shift in an enzyme's function that could help expand the toolbox for engineering biofuels and other plant-based oil products. The results will be published online the week of September 8, 2008, in the Proceedings of the National Academy of Sciences.

Enzyme Detectives Uncover New Reactions, Products: Implications for engineering biofuels and plant-derived replacements for petro-chemicals

UPTON, NY | Posted on September 8th, 2008

The Brookhaven scientists were trying to understand the factors that affect where carbon-carbon double bonds are placed in fatty acids, the building blocks of oils and fats, when they are "desaturated" — that is, when a desaturase enzyme removes hydrogen from the carbon chain.

"Placing double bonds in different positions allows you to change the structure of the fatty acids to make products with different potential applications," explained Brookhaven biochemist John Shanklin, who led the research. The ultimate goal: engineering designer plant oils to be used as biofuels and/or raw materials to reduce the use of petroleum.

To try to change the position of a double bond, the Brookhaven team modified a desaturase enzyme, changing three of the 363 amino acids in its protein sequence. But when they tested the modified enzyme and looked for the expected product with its altered double-bond position, it wasn't there.

They could have moved on and made different amino acid changes to accomplish the initial goal. But Brookhaven research associate Edward Whittle was determined to figure out what was going on with the unusual result. "The substrate, or starting material, had been used up, so something was being produced — substrates can't just disappear," Whittle said. "If it wasn't the product we were looking for, what was it?"

Whittle's detective work uncovered a remarkable discovery. Instead of producing a shift in double-bond position, the enzyme modification had yielded three completely new products — two variations of a hydroxylated product called an allylic alcohol and a fatty acid containing two double bonds. "This was a profound shift in enzyme function," noted Shanklin, who has been working with modified enzymes for 15 years. "Usually you make changes very gradually, getting a few percent of a new product mixed with the original product. This was more like throwing a switch, making the change in function close to complete."

The discovery is also notable because the starting enzyme, like other soluble (membrane-independent) desaturases, can ordinarily perform only its one specified reaction — desaturation. This is unlike desaturase enzymes that reside within the cell membrane, which appear to be more versatile, performing a range of reactions. The soluble and membrane enzymes, however, do share one key feature: both perform reactions that require the production of a highly reactive form of oxygen.

"Since both classes of enzymes produce activated oxygen, in theory the soluble enzymes, like their membrane counterparts, should be able to perform a variety of reactions as well," Shanklin said. "Our work demonstrates that this is indeed the case. Making small changes to the enzyme's amino acid sequence has unlocked the soluble desaturase's potential to facilitate a wider range of chemistry than has been seen before," Shanklin said.

The challenge is to figure out how these structural changes to the enzyme lead to the observed changes in reaction chemistry. Computer-generated models combining the known structure of the starting enzyme in conjunction with its new substrates are helping the scientists understand how the enzyme works. The next step is to obtain real 3-D crystal structures of enzyme-substrate complexes, using the National Synchrotron Light Source at Brookhaven Lab, to see how they match up with the predictions.

Analyzing the structures of soluble enzymes is much simpler than obtaining structures for membrane enzymes. So, in effect, this work is a fast-track approach for correlating structure with function, which should help scientists gain general mechanistic insights relevant to both classes of enzymes. "Understanding how nature has figured out how to do this very difficult chemistry, and how to control that chemistry," Shanklin said, "would be extremely satisfying from a purely scientific perspective. But applying this knowledge could have benefits for us all."

"Right now, the materials we use — the plastics, foams, nylons — have been limited by the structures of petroleum-based chemical feedstocks. But if we understand how to engineer designer desaturase-like plant enzymes, we can tailor-make feedstocks with optimal properties, instead of relying on the properties of preexisting raw materials," said Shanklin. "We'd no longer have to say, ‘this is what we have so this is what we can make.' Instead, we could make the best feedstock for a particular application by designing the raw materials that will yield it."

This research was funded by the Office of Basic Energy Sciences within DOE's Office of Science, and by the Natural Sciences and Engineering Research Council of Canada. In addition to Shanklin and Whittle, the research team includes Amy Tremblay and Peter Buist of Carleton University in Ottawa, Canada.

####

About Brookhaven National Laboratory
One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

For more information, please click here

Contacts:
Karen McNulty Walsh
(631) 344-8350

or
Mona S. Rowe
(631) 344-5056

Copyright © Brookhaven National Laboratory

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

A breakthrough in imaging gold nanoparticles to atomic resolution by electron microscopy August 22nd, 2014

Ultra-short pulse lasers & Positioning August 21st, 2014

Malvern’s Dr Alan Rawle talks TLAs in plenary lecture at Particulate Systems Analysis conference August 21st, 2014

Water window imaging opportunity: A new theoretical study elucidates mechanisms that could help in producing coherent radiations, ultimately promoting high-contrast imaging of biological samples August 21st, 2014

Laboratories

Shaping the Future of Nanocrystals: Berkeley Lab Researchers Obtain First Direct Observation of Facet Formation in Nanocubes August 21st, 2014

Promising Ferroelectric Materials Suffer From Unexpected Electric Polarizations: Brookhaven Lab scientists find surprising locked charge polarizations that impede performance in next-gen materials that could otherwise revolutionize data-driven devices August 18th, 2014

Videos/Movies

The channel that relaxes DNA: Relaxing DNA strands by using nano-channels: Instructions for use August 20th, 2014

Chemistry

Production of Toxic Ion Nanosorbents with High Sorption Capacity in Iran August 17th, 2014

Scientists fold RNA origami from a single strand: RNA origami is a new method for organizing molecules on the nanoscale. Using just a single strand of RNA, this technique can produce many complicated shapes. August 14th, 2014

Could hemp nanosheets topple graphene for making the ideal supercapacitor? August 12th, 2014

Iranians Find Novel Method for Processing Highly Pure Ceramic Nanoparticles August 12th, 2014

Discoveries

A breakthrough in imaging gold nanoparticles to atomic resolution by electron microscopy August 22nd, 2014

Shaping the Future of Nanocrystals: Berkeley Lab Researchers Obtain First Direct Observation of Facet Formation in Nanocubes August 21st, 2014

Water window imaging opportunity: A new theoretical study elucidates mechanisms that could help in producing coherent radiations, ultimately promoting high-contrast imaging of biological samples August 21st, 2014

Nanotechnology Helps Production of Super Adsorbent Polymers August 21st, 2014

Announcements

A breakthrough in imaging gold nanoparticles to atomic resolution by electron microscopy August 22nd, 2014

Ultra-short pulse lasers & Positioning August 21st, 2014

Malvern’s Dr Alan Rawle talks TLAs in plenary lecture at Particulate Systems Analysis conference August 21st, 2014

Water window imaging opportunity: A new theoretical study elucidates mechanisms that could help in producing coherent radiations, ultimately promoting high-contrast imaging of biological samples August 21st, 2014

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE