Spinach gave Popeye super strength, but it also holds the promise of a different power for a group of scientists: the ability to convert sunlight into a clean, efficient alternative fuel.
Purdue University physicists are part of an international group using spinach to study the proteins involved in photosynthesis, the process by which plants convert the sun’s energy into carbohydrates used to power cellular processes.
“The proteins we study are part of the most efficient system ever built, capable of converting the energy from the sun into chemical energy with an unrivaled 60 percent efficiency,” said Yulia Pushkar, a Purdue assistant professor of physics involved in the research. “Understanding this system is indispensible for alternative energy research aiming to create artificial photosynthesis.”
During photosynthesis plants use solar energy to convert carbon dioxide and water into hydrogen-storing carbohydrates and oxygen. Artificial photosynthesis could allow for the conversion of solar energy into renewable, environmentally friendly hydrogen-based fuels.
In Pushkar’s laboratory, students extract a protein complex called Photosystem II from spinach they buy at the supermarket. It is a complicated process performed over two days in a specially built room that keeps the spinach samples cold and shielded from light, she said.
Once the proteins have been carefully extracted, the team excites them with a laser and records changes in the electron configuration of their molecules.
“These proteins require light to work, so the laser acts as the sun in this experiment,” Pushkar said. “Once the proteins start working, we use advanced techniques like electron paramagnetic resonance and X-ray spectroscopy to observe how the electronic structure of the molecules change over time as they perform their functions.”
Photosystem II is involved in the photosynthetic mechanism that splits water molecules into oxygen, protons and electrons. During this process a portion of the protein complex, called the oxygen-evolving complex, cycles through five states in which four electrons are extracted from it, she said.
The international team recently revealed the structure of the first and third states at a resolution of 5 and 5.5 Angstroms, respectively, using a new technique called serial femtosecond crystallography. A paper detailing the results was published in Nature and is available online. In addition to Pushkar, Purdue postdoctoral researcher Lifen Yan and former Purdue graduate student Katherine Davis participated in the study and are paper co-authors.
Petra Fromme, professor of chemistry and biochemistry at Arizona State University, leads the international team.
“The trick is to use the world’s most powerful X-ray laser, named LCLS, located at the Department of Energy’s SLAC National Accelerator Laboratory,” said Fromme in a statement. “Extremely fast femtosecond (one-quadrillionth of a second) laser pulses record snapshots of the PSII crystals before they explode in the X-ray beam, a principle called ‘diffraction before destruction.’”
While X-ray crystallography reveals structural changes, it does not provide details of how the electronic configurations evolve over time, which is where the Purdue team’s work came in. The Purdue team mimicked the conditions of the serial femtosecond crystallography experiment, but used electron paramagnetic resonance to reveal the electronic configurations of the molecules, Pushkar said.
“The electronic configurations are used to confirm what stage of the process Photosystem II is in at a given time,” she said. “This information is kind of like a time stamp and without it the team wouldn’t have been able to put the structural changes in context.”
The National Science Foundation and Department of Energy funded the Purdue team’s work.
Writer: Elizabeth Gardner, 765-494-2081, email@example.com
Source: Yulia Pushkar, 765-496-3279, firstname.lastname@example.org
ASU news release:
Elizabeth K. Gardner | Eurek Alert!
Using DNA origami to build nanodevices of the future
31.08.2015 | Institute for Integrated Cell-Material Sciences at Kyoto University
An ounce of prevention: Research advances on 'scourge' of transplant wards
28.08.2015 | University of Wisconsin-Madison
The leaves of the lotus flower, and other natural surfaces that repel water and dirt, have been the model for many types of engineered liquid-repelling surfaces. As slippery as these surfaces are, however, tiny water droplets still stick to them. Now, Penn State researchers have developed nano/micro-textured, highly slippery surfaces able to outperform these naturally inspired coatings, particularly when the water is a vapor or tiny droplets.
Enhancing the mobility of liquid droplets on rough surfaces could improve condensation heat transfer for power-plant heat exchangers, create more efficient...
Longer, more severe, and hotter droughts and a myriad of other threats, including diseases and more extensive and severe wildfires, are threatening to transform some of the world's temperate forests, a new study published in Science has found. Without informed management, some forests could convert to shrublands or grasslands within the coming decades.
"While we have been trying to manage for resilience of 20th century conditions, we realize now that we must prepare for transformations and attempt to ease...
A University of Oklahoma astrophysicist and his Chinese collaborator have found two supermassive black holes in Markarian 231, the nearest quasar to Earth, using observations from NASA's Hubble Space Telescope.
The discovery of two supermassive black holes--one larger one and a second, smaller one--are evidence of a binary black hole and suggests that supermassive...
A team of European researchers have developed a model to simulate the impact of tsunamis generated by earthquakes and applied it to the Eastern Mediterranean. The results show how tsunami waves could hit and inundate coastal areas in southern Italy and Greece. The study is published today (27 August) in Ocean Science, an open access journal of the European Geosciences Union (EGU).
Though not as frequent as in the Pacific and Indian oceans, tsunamis also occur in the Mediterranean, mainly due to earthquakes generated when the African...
In mountainous regions earthquakes often cause strong landslides, which can be exacerbated by heavy rain. However, after an initial increase, the frequency of these mass wasting events, often enormous and dangerous, declines, in fact independently of meteorological events and aftershocks.
These new findings are presented by a German-Franco-Japanese team of geoscientists in the current issue of the journal Geology, under the lead of the GFZ...
20.08.2015 | Event News
20.08.2015 | Event News
19.08.2015 | Event News
01.09.2015 | Press release
01.09.2015 | Materials Sciences
01.09.2015 | Materials Sciences