Foodconsumer.org

 
USCards.com Bookmark Us
All Food, Diet and Health News 
 
 Misc. News
 Must-Read News
 Letter to Editor
 Featured Products
 Recalls & Alerts
 Consumer Affair
 Non-food Things
 Health Tips
 Interesting Sites
 
 Diet & Health
 Heart & Blood
 Cancer
 Body Weight
 Children & Women
 General Health
 Nutrition
 
 Food & Health
 Food Chemicals
 Biological Agents
 Cooking & Packing
 Technologies
 Agri. & Environ.
 Laws & Politics
 
 General Health
 Drug News
 Diseases
 Mental Health
 Infectious Disease
 Environment
 Lifestyle
 Government
 Other News
 
 Food Consumer
 FC News & Others
Search





Search Foodconsumer & Others


Add to Google
Add to My Yahoo
Newsfeed

foodconsumer.org news feed
Su bmit news[release]



More than 100 credit cards available at uscards.com from uscards.com, you can pick more than 100 credit cards


Diet & Health : Nutrition Last Updated: Apr 20, 2011 - 9:38:09 AM


MIT biologists solve vitamin puzzle
By news release
Mar 22, 2007 - 7:25:34 PM

E.mail t.his a.rticle
 P.rinter f.riendly p.age
Get n.ewsletter
 
   

MIT biologists solve vitamin puzzle

Anne Trafton, News Office
March 21, 2007

 

Solving a mystery that has puzzled scientists for decades, MIT and Harvard researchers have discovered the final piece of the synthesis pathway of vitamin B12--the only vitamin synthesized exclusively by microorganisms.

B12, the most chemically complex of all vitamins, is essential for human health. Four Nobel Prizes have been awarded for research related to B12, but one fragment of the molecule remained an enigma--until now.

The researchers report that a single enzyme synthesizes the fragment, and they outline a novel reaction mechanism that requires cannibalization of another vitamin.

The work, which has roots in an MIT undergraduate teaching laboratory, "completes a piece of our understanding of a process very fundamental to life," said Graham Walker, MIT professor of biology and senior author of a paper on the work that will appear in the March 22 online edition of Nature.

Vitamin B12 is produced by soil microbes that live in symbiotic relationships with plant roots. During the 1980s, an undergraduate research course taught by Walker resulted in a novel method for identifying mutant strains of a soil microbe that could not form a symbiotic relationship with a plant.

Walker's team has now found that one such mutant has a defective form of an enzyme known as BluB that leaves it unable to synthesize B12.

BluB catalyzes the formation of the B12 fragment known as DMB, which joins with another fragment, produced by a separate pathway, to form the vitamin. One of several possible reasons why it took so long to identify BluB is that some bacteria lacking the enzyme can form DMB through an alternate pathway, Walker said.

One of the most unusual aspects of BluB-catalyzed synthesis is its cannibalization of a cofactor derived from another vitamin, B2. During the reaction, the B2 cofactor is split into more than two fragments, one of which becomes DMB.

Normally, the B2-derived cofactor would assist in a reaction by temporarily holding electrons and then giving them away. Such cofactors are not consumed in the reaction.

Cannibalization of a cofactor has very rarely been observed before in vitamin synthesis or any type of biosynthetic pathway, says Michiko Taga, an MIT postdoctoral fellow in Walker's lab and lead co-author of the Nature paper.

"There are almost no other examples where the cofactor is used as a substrate," she said.

One early clue to BluB's function was that a gene related to it is located near several other genes involved in B12 synthesis in a different bacterium. Still, the researchers were not convinced that one enzyme could perform all of the complicated chemistry needed to produce DMB.

"It looked like a number of things had to happen in order to make the DMB," said Walker. "We originally thought that BluB might be just one of several enzymes involved in DMB synthesis."

Therefore, it came as a surprise when Taga isolated the BluB protein and showed that it could make DMB all by itself.

Nicholas Larsen, lead co-author and a former college classmate of Taga's now at Harvard Medical School, did a crystallographic analysis of the protein after Taga told him about her research over coffee one day. The protein structure he developed clearly shows the "pocket" of BluB where the DMB synthesis reaction takes place.

Still to be explored is the question of why soil bacteria synthesize B12 at all, Walker said. Soil microorganisms don't require B12 to survive, and the plants they attach themselves to don't need it either, so he speculates that synthesizing B12 may enable the bacteria to withstand "challenges" made by the plants during the formation of the symbiotic relationship.

More than 30 genes are involved in vitamin B12 synthesis, and "that's a lot to carry around if you don't need to make it," Walker said.

The full implications of the new research will probably not be known for some years, which is often the case with basic research, Walker said. "I've been in many other situations in research where we did something very basic and did not immediately realize the importance of it, and subsequently the implications were found to be much more broad-reaching," he said.

Other authors on the paper are Annaleise Howard-Jones, a postdoctoral fellow at Harvard Medical School, and Christopher Walsh, professor of biological chemistry and molecular pharmacology at Harvard Medical School.

The research was funded by the National Institutes of Health and the Jane Coffin Childs Memorial Fund for Medical Research.

 

77 massachusetts avenue

cambridge, ma 02139-4307

617-253-2700

newsoffice





© 2004-2008 by foodconsumer.org unless otherwise specified

Top of Page




Google
 
Web foodconsumer.org

Search Consumer-friendly Health Sites












We have moved to Food Consumer . Org



disclaimer | advertising | jobs | privacy | about us | newsletter | Submit news/articles
link partners: | Buy Viagra | MarketAmerica.com |
Buy a home | Auto Insurance | Mortgage refinancing | DaytonaCPA.com | Take Your Blog to a Higher Level
© Copyright 2004 - 2008 foodconsumer.org All rights reserved

Disclaimer: What's published on this website should be considered opinions of respective writers only and foodconsumer.org which has no political agenda nor commercial ambition may or may not endorse any opinion of any writer. No accuracy is guaranteed although writers are doing their best to provide accurate information only. The information on this website should not be construed as medical advice and should not be used to replace professional services provided by qualified or licensed health care workers. The site serves only as a platform for writers and readers to share knowledge, experience, and information from the scientific community, organizations, government agencies and individuals. Foodconsumer.org encourages readers who have had medical conditions to consult with licensed health care providers - conventional and or alternative medical practitioners.