Physics and Astronomy Prof. Yulia Pushkar publishes photosynthesis paper


Any middle school student can tell you that photosynthesis is the process of plants turning light energy into chemical energy and, later, oxygen. It’s the building block to life on Earth.

But how does photosynthesis really work? And how can it be replicated easier and better with technology.

A new paper published in Nature by Physics and Astronomy Prof. Yulia Pushkar, her postdoc Linfen Yan, former Purdue Physics graduate student Kate Davis, and several other international scientists looks at how particles react within the photosystem II protein during photosynthesis. Pushkar wrote about PSII as a complex protein that “catalyzes the light-driven water splitting process, which maintains the Earth’s oxygenic atmosphere.”

Pushkar concentrated her research on the protein within the oxygen-evolving complex extracted from spinach. The complex is where the oxygen stems from when sunlight occurs.

Using crystallography, X-ray spectroscopy and the stream from an electron laser, Pushkar and her team investigated the structure and particles that help drive photosynthesis and, thus, life itself.

“It is a complicated two-day process, which is conducted mostly in the dark while keeping samples cold. For PS II preparation, we had to install a cold room in the basement of the Physics department,” Pushkar explained. “For this research, PS II is prepared in a form of nano-crystals and changes in the structure after light excitation are tracked by time resolved crystallography.”

Pushkar revealed that three grocery bags worth of spinach spun in a centrifuge in the biophysics lab are needed to produce just 80 milligrams of protein to explore. Popeye would be very interested in this research.

In the laser lab, Pushkar and her team recreated the sun with the laser. Two quick bursts are enough to make the protein react into photosystem II. The data mined from the X-ray spectrometry is analyzed and the particle secrets of the reaction are brought to light.

“When we study the structure of this complex with crystallography, we can see every atom in this huge structure at large resolution,” Pushkar said. “This paper focuses on a free state when the structure of the complex suddenly changes.  We are looking at the densities and the shape of the cluster and then, of course, the future question is how to connect the change with the exact mechanism of how this cluster works.”

Yulia Pushkar with laser

Physics and Astronomy Prof. Yulia Pushkar and her postdoc Lifen Yan ready an electron laser that works to replicate the sun during their photosynthesis research.

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