 |
|
Protein enables discovery of quantum effect in photosynthesis
May 03, 2007When it comes to studying energy transfer in photosynthesis, it's good to think "outside the bun."
That's what Robert Blankenship, Ph.D., professor of biology and chemistry in Arts & Sciences at Washington University in St. Louis, did when he contributed a protein to a study performed by his collaborators at Lawrence Berkeley National Laboratory and the University of California at Berkeley.
Taco shell protein
It's called bacteriochlorophyl (BChl) a protein, but Blankenship fondly calls it the taco shell protein because of its structure: its ribbon-like backbone wraps around three clusters of seven chlorophylls, just like a taco shell around ground beef. The structure also is referred to as trimeric because of the three clusters.
The protein, which comes from a photosynthetic bacterium that lives in extremely high temperatures, enabled the researches to discover that quantum mechanical effects appear to play a role in photosynthesis.
The taco shell protein is arguably the most studied and understood protein in a complex photosynthesis researchers refer to as the antenna system, molecules that efficiently transfer energy from light in a cascade.
Photosynthesis transforms light, carbon dioxide and water into chemical energy in plants and some bacteria. The wavelike characteristic of this energy transfer process can explain its extreme efficiency, in that vast areas of phase space can be sampled effectively to find the most efficient path for energy transfer.
"We have a very detailed molecular structure of this protein and we understand the electronic properties of it very well, too," said Blankenship. "It's taught us a lot about how chlorophylls interact with proteins. It was ideal for this study."
Blankenship's colleague, Graham R. Fleming, Ph.D., deputy director of the U.S. Department of Energy's Lawrence Berkeley National Laboratory and professor of chemistry at the University of California, and colleagues used 2-D spectroscopy to study what happens inside a bacteriochlorophyll complex, and detected a 'quantum beating."
The effect, described in the April 12, 2007, issue of Nature, occurs when light-induced excitations in the complex meet and interfere constructively, much like the interactions that occur between the ripples formed by throwing stones into a pond.
The collaboration is a good illustration of interdisciplinary science. The Washington University group's expertise is in photosynthesis, especially antenna systems, and the West Coast group's specialty is advanced laser techniques. The quantum finding would have been impossible without collaboration.
Good vibrations
"We have obtained the first direct evidence that remarkably long-lived wavelike electronic quantum coherence plays an important part in energy transfer processes during photosynthesis," said Fleming, the principal investigator for the study. "This wavelike characteristic can explain the extreme efficiency of the energy transfer because it enables the system to simultaneously sample all the potential energy pathways and choose the most efficient one."
Fleming is also a professor of chemistry at UC Berkeley, and an internationally acclaimed leader in spectroscopic studies of the photosynthetic process. In a paper entitled, "Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems," he and his collaborators report the detection of "quantum beating" signals — coherent electronic oscillations in both donor and acceptor molecules — generated by light-induced energy excitations, like the ripples formed when stones are tossed into a pond.
Electronic spectroscopy measurements made on a femtosecond (millionths of a billionth of a second) time-scale showed these oscillations meeting and interfering constructively, forming wavelike motions of energy (superposition states) that can explore all potential energy pathways simultaneously and reversibly, meaning they can retreat from wrong pathways with no penalty. This finding contradicts the classical description of the photosynthetic energy transfer process as one in which excitation energy hops from light-capturing pigment molecules to reaction center molecules step-by-step down the molecular energy ladder.
"The classical hopping description of the energy transfer process is both inadequate and inaccurate," said Fleming. "It gives the wrong picture of how the process actually works, and misses a crucial aspect of the reason for the wonderful efficiency."
The taco shell is a sort of "middleman" in the antenna system, sandwiched in between a larger antenna and a molecule called the Reaction Center, where all the chemistry in energy transfer takes place, said Blankenship.
"Most of the absorption of light is carried out by a complex called the chlorosome that then transfers the energy to the trimeric protein that in turn transfers to the Reaction Center," Blankenship said.
Washington University in St. Louis
It's called bacteriochlorophyl (BChl) a protein, but Blankenship fondly calls it the taco shell protein because of its structure: its ribbon-like backbone wraps around three clusters of seven chlorophylls, just like a taco shell around ground beef. The structure also is referred to as trimeric because of the three clusters.
The protein, which comes from a photosynthetic bacterium that lives in extremely high temperatures, enabled the researches to discover that quantum mechanical effects appear to play a role in photosynthesis.
The taco shell protein is arguably the most studied and understood protein in a complex photosynthesis researchers refer to as the antenna system, molecules that efficiently transfer energy from light in a cascade.
Photosynthesis transforms light, carbon dioxide and water into chemical energy in plants and some bacteria. The wavelike characteristic of this energy transfer process can explain its extreme efficiency, in that vast areas of phase space can be sampled effectively to find the most efficient path for energy transfer.
"We have a very detailed molecular structure of this protein and we understand the electronic properties of it very well, too," said Blankenship. "It's taught us a lot about how chlorophylls interact with proteins. It was ideal for this study."
Blankenship's colleague, Graham R. Fleming, Ph.D., deputy director of the U.S. Department of Energy's Lawrence Berkeley National Laboratory and professor of chemistry at the University of California, and colleagues used 2-D spectroscopy to study what happens inside a bacteriochlorophyll complex, and detected a 'quantum beating."
The effect, described in the April 12, 2007, issue of Nature, occurs when light-induced excitations in the complex meet and interfere constructively, much like the interactions that occur between the ripples formed by throwing stones into a pond.
The collaboration is a good illustration of interdisciplinary science. The Washington University group's expertise is in photosynthesis, especially antenna systems, and the West Coast group's specialty is advanced laser techniques. The quantum finding would have been impossible without collaboration.
Good vibrations
"We have obtained the first direct evidence that remarkably long-lived wavelike electronic quantum coherence plays an important part in energy transfer processes during photosynthesis," said Fleming, the principal investigator for the study. "This wavelike characteristic can explain the extreme efficiency of the energy transfer because it enables the system to simultaneously sample all the potential energy pathways and choose the most efficient one."
Fleming is also a professor of chemistry at UC Berkeley, and an internationally acclaimed leader in spectroscopic studies of the photosynthetic process. In a paper entitled, "Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems," he and his collaborators report the detection of "quantum beating" signals — coherent electronic oscillations in both donor and acceptor molecules — generated by light-induced energy excitations, like the ripples formed when stones are tossed into a pond.
Electronic spectroscopy measurements made on a femtosecond (millionths of a billionth of a second) time-scale showed these oscillations meeting and interfering constructively, forming wavelike motions of energy (superposition states) that can explore all potential energy pathways simultaneously and reversibly, meaning they can retreat from wrong pathways with no penalty. This finding contradicts the classical description of the photosynthetic energy transfer process as one in which excitation energy hops from light-capturing pigment molecules to reaction center molecules step-by-step down the molecular energy ladder.
"The classical hopping description of the energy transfer process is both inadequate and inaccurate," said Fleming. "It gives the wrong picture of how the process actually works, and misses a crucial aspect of the reason for the wonderful efficiency."
The taco shell is a sort of "middleman" in the antenna system, sandwiched in between a larger antenna and a molecule called the Reaction Center, where all the chemistry in energy transfer takes place, said Blankenship.
"Most of the absorption of light is carried out by a complex called the chlorosome that then transfers the energy to the trimeric protein that in turn transfers to the Reaction Center," Blankenship said.
Washington University in St. Louis
Photosynthesis Current Events and Photosynthesis News RSSChemists describe solar energy progress and challenges, including the 'artificial leaf'
Scientists are making progress toward development of an "artificial leaf" that mimics a real leaf's chemical magic with photosynthesis - but instead converts sunlight and water into a liquid fuel such as methanol for cars and trucks.
Toward home-brewed electricity with 'personalized solar energy'
New scientific discoveries are moving society toward the era of "personalized solar energy," in which the focus of electricity production shifts from huge central generating stations to individuals in their own homes and communities.
Sun or shade: Pecan leaves' photosynthetic light response evaluated
Pecan, the most valuable nut tree native to North America, is native from northern Illinois and southeastern Iowa to the Gulf Coast of the United States, where it grows abundantly along the Mississippi River, the rivers of central and eastern Oklahoma, and Texas.
Reflective film can boost profits for apple growers
In a research report published in a recent issue of HortTechnology, scientists Ignasi Iglesias and Simó Alegre examined the effects of covering orchard floors with reflective films on fruit color, fruit quality, canopy light distribution, orchard temperature, and profitability.
Iron controls patterns of nitrogen fixation in the Atlantic
Scientists including researchers from the National Oceanography Centre, Southampton and the University of Essex have discovered that interactions between iron supply, transported through the atmosphere from deserts, and large-scale oceanic circulation control the availability of a crucial nutrient, nitrogen, in the Atlantic.
Heavy metals accumulate more in some mushrooms than in others
A research team from the University of Castilla-La Mancha (UCLM) has analysed the presence of heavy metals in 12 species of mushroom collected from non-contaminated natural areas, and has found that the levels vary depending on the type of mushroom.
Arctic land and seas account for up to 25 percent of world's carbon sink
In a new study in the journal Ecological Monographs, ecologists estimate that Arctic lands and oceans are responsible for up to 25 percent of the global net sink of atmospheric carbon dioxide.
Early hominid first walked on two legs in the woods
Among the many surprises associated with the discovery of the oldest known, nearly complete skeleton of a hominid is the finding that this species took its first steps toward bipedalism not on the open, grassy savanna, as generations of scientists - going back to Charles Darwin - hypothesized, but in a wooded landscape.
Light, photosynthesis help bacteria invade fresh produce
Exposure to light and possibly photosynthesis itself could be helping disease-causing bacteria to be internalized by lettuce leaves, making them impervious to washing, according to research published in the October issue of the journal Applied and Environmental Microbiology.
'Green Clean:' Researchers Determining Natural Ways To Clean Contaminated Soil
Researchers at North Carolina State University are working to demonstrate that trees can be used to degrade or capture fuels that leak into soil and ground water. Through a process called phytoremediation - literally a "green" technology - plants and trees remove pollutants from the environment or render them harmless.
More Photosynthesis Current Events and Photosynthesis News Articles
 |
Photosynthesis (Science Concepts, Second Series) by Alvin Silverstein (Author), Virginia B. Silverstein (Author), Laura Silverstein Nunn (Author) Explains photosynthesis, the process responsible for providing the material and energy for all living things, and discusses such related issues as respiration, the carbon cycle, acid rain, and the greenhouse effect. |
 |
Molecular Mechanisms of Photosynthesis by Robert E Blankenship (Author) Molecular Mechanisms of Photosynthesis stands as an ideal introduction to this subject. Robert Blankenship, a leading authority in photosynthesis research, offers a modern approach to photosynthesis in this accessible and well-illustrated text. The book provides a concise overview of the basic principles of energy storage and the history of the field, then progresses into more advanced topics such as electron transfer pathways, kinetics, genetic manipulations, and evolution. Throughout, Blankenship includes an interdisciplinary emphasis that makes this book appealing across fields. Leading authority in Photosynthesis and the the President of the International Society of Photosynthesis Research. First authoritative text to enter the market in 10 years. Stresses an... |
 |
What Is Photosynthesis? DVD Starring: Artist Not Provided Photosynthesis is a biological process that benefits all living things. The chemical reactions that occur during the process of photosynthesis are described with the help of graphics and easy-to-follow explanations. This video makes learning about plants and how they function both fun and interesting. |
 |
Photosynthesis: Changing Sunlight into Food (Nature's Changes) by Bobbie Kalman (Author) This title contains a book & CD. Photosynthesis is the basis for all life on Earth! This exciting and sensitive book looks at how plants use a gas that is poisonous to people and animals to create food and oxygen for all creatures with the help of the Sun. The CD's approximate running time is 30 minutes. |
 |
Phonosynthesis by DJ Irene |
 |
Photosynthesis by Dr David Lawlor (Author) Now in its third edition, this book describes photosynthesis by considering the partial processes involved throughout the various level of plant (cell, organelle and molecule), and their contributions to the complete process. It also considers the molecular and biochemical events which take place in the photosynthetic system. Finally, it explains how these determine the physiological characteristics of plant productivity. |
 |
Photosynthesis Also With: Josh Kalis (Primary Contributor), Rob Dyrdek (Primary Contributor), Jason Dill (Primary Contributor), Danny Way (Primary Contributor), Anthony van Engelen (Primary Contributor), Anthony Pappalardo (Primary Contributor), Pat Corcoran (Primary Contributor), Kerry Getz (Primary Contributor), Fred Gall (Primary Contributor), Tim O'Connor (Primary Contributor) Skater list Anthony Pappalardo Anthony Van Engelen Danny Garcia Fred Gall Jason Dill Josh Kalis Kerry Getz Mark Appleyard Pat Corcoran Rob Dyrdek Tim O'Connor |
 |
Understanding Photosynthesis with Max Axiom, Super Scientist (Graphic Science series) by Liam O'Donnell (Author), Richard Dominguez (Illustrator), Charles (Illustrator), III Barnett (Illustrator) In graphic novel format, follows the adventures of Max Axiom, a science teacher and super-cool super-scientist, as he explains the science behind photosynthesis. |
 |
Photosynthesis Rhyme, Results Rhythm (Primary Contributor) |
 |
Vintage Photosynthesis Biochemistry Science Film DVD: Classic Water, Oxygen Cycle, Plant Life, Sunlight & Carbon Video Photosynthesis is pretty much the most important biological process that takes place on this planet, because almost everything living depends on photosynthesis to survive. Gift of Green is a vintage science film dealing with the process of photosynthesis. Now, this digitized film is available on DVD for the first time ever! Table Of Contents: (1) Gift of Green (1946) - This is a vintage science class film featuring animation that shows the process of photosynthesis. Highly recommended and well-made for its era! - 16 Minutes |
| © 2009 BrightSurf.com |