It Has Only Taken Us 3.2 Billion Years to Catch Up to Primitive Bacteria

Primitive bacteria learned to split water using sunlight over 3 billion years ago. That crucial part of photosynthesis paved the way for life as we know it on Earth. Now researchers at the US DOE Lawrence Berkeley National Lab have taken a huge step in understanding this critical step--which should eventually result in much improved efficiencies in renewable energy.

Specifically, an international team led by scientists from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) pieced together high-resolution (approximately 0.15 Ångstrom) structures of a Mn4Ca cluster found in a photosynthetic protein complex (one Ångstrom equals one ten-billionth of a meter). The team, which includes scientists from Germany’s Technical and Free Universities in Berlin, the Max Planck Institute in Mülheim, and the Stanford Synchrotron Radiation Laboratory, used an innovative combination of x-ray spectroscopy and protein crystallography to yield the highest-resolution structures yet of the metal catalyst.

“This is the first study to combine x-ray absorption spectroscopy and crystallography in such a detailed manner to determine the structure of an active metal site in a protein, especially something as complicated as the photosynthetic Mn4Ca cluster,” says Junko Yano of Berkeley Lab’s Physical Biosciences Division, who is one of the lead authors of the study.

The metal catalyst resides in a large protein complex, called photosystem II, found in plants, green algae, and cyanobacteria. The system drives one of nature’s most efficient oxidizing reactions by using light energy to split water into oxygen, protons, and electrons. Because of its efficiency and reliance on nothing more than the sun, the catalyst has become a target of scientists working to develop carbon-neutral sources of energy. Learn the catalyst’s structure, then how it works, and perhaps scientists can develop similarly robust molecules.

But until now, the precise structure of the catalyst has eluded all attempts of determination by x-ray diffraction and various spectroscopic techniques. Even a 3.0-Ångstrom-resolution structure obtained by the Berkeley Lab group’s collaborators at the Technical and Free Universities in Berlin, using x-ray diffraction, didn’t allow the researchers to pinpoint the exact positions of the cluster’s manganese and calcium atoms and its surrounding ligands.

Much more at Source.

There are many more research teams working on understanding the various processes in photosynthesis and electron transport, including the two teams detailed in this previous Al Fin posting. Once science has a firm understanding of a natural process, it can then proceed to modify the process for specific human purposes.