Spinach gives Popeye a superpower, a fictional sailor. But in the real world, spinach is a challenge for scientists. Especially related to its ability to convert sunlight into a clean and efficient alternative fuel.
Physicist Purdue University, part of an international study group, has used spinach to study proteins involved in photosynthesis. Namely a process whereby plants convert solar energy into carbohydrates and are used as power on the cellular process.
"The proteins we studied are part of the most efficient system ever built, which is capable of converting energy from the sun into chemical energy with unmatched efficiency. That is to generate energy up to 60 percent, "said Yulia Pushkar, an assistant professor of physics at Purdue involved in this study.
"Understanding this system is indispensable for alternative energy research aimed at creating artificial photosynthesis," Pushkar said.
During photosynthesis, plants use solar energy to convert carbon dioxide and water into hydrogen and oxygen carbohydrates.
Artificial photosynthesis can allow for the conversion of solar energy into renewable energy, which is environmentally friendly hydrogen-based fuel.
In Pushkar's laboratory, students take a protein complex called Photosystem II from spinach that they buy at a supermarket. This is a complicated process done because it lasts for two days in a special room. Inside the room the students made a sample of cold spinach and sheltered from the light.
Once the proteins are successfully extracted carefully, the team activates them with a laser and they note changes in electron configuration of their molecules.
"This protein needs light to work, so the laser acts as the sun in this experiment," Pushkar said. "Once the proteins start working, we use advanced techniques such as paramagnetic resonance electrons and X-ray spectroscopy to observe how the electronic structure of the molecules changes over time as they perform their functions," Pushkar added.
Photosystem II is involved in the mechanism of photosynthesis that divides water molecules into oxygen, protons, and electrons. During this process, some of the complex proteins called oxygen complex will develop.
In addition to the Pushkar team, the international team recently also revealed the first and third country structures at 5 and 5.5 Angstrom resolutions, respectively, using a new technique called the femtosecond crystallographic series.
In addition to Pushkar, postdoctoral researchers at Perdue, Lifen Yan and former Purdue graduate student Katherine Davis participated in the study. While Petra Fromme, professor of chemistry and biochemistry at Arizona State University, was appointed to lead the international team.
"This femtosecond crystallographic technique using the most powerful X-ray Laser in the world, named LCLS, is located in the Department of Energy SLAC National Accelerator Laboratory," Fromme said in a statement.
"Femtoseconds are very fast (satepep of the second) laser pulse snapshot notes of the PSII crystal before they explode in X-ray light, a principle called 'diffraction before destruction.'
In this team, Purdue mimicked the experimental conditions of femtosecond crystallography, but uses paramagnetic resonance electrons to reveal the electronic configuration of molecules.