How Nature splits water and powers the planet

The study reveals how the cofactor is activated, a process that involves the highly regulated uptake of water from its surroundings. (c) MPICEC

The splitting of two water molecules into oxygen using sunlight is the first step of photosynthesis, a process performed by plants and cyanobacteria. The overall reaction operates much the same way as a roof-top solar panel, harvesting light energy from the sun.

But instead of generating electricity, the energy is used to produce chemical compounds like carbohydrates, the food animals and humans consume. It has also created the oxygen rich atmosphere of our planet, and the protective ozone layer, which shields the surface from harmful UV radiation.

The study, led by Dr. Nick Cox, a former group leader of MPI CEC in the Department of Prof. Wolfgang Lubitz, now at ANU Research School of Chemistry, focused on the photosynthetic enzyme which performs biological water splitting, Photosystem II. Buried within this large protein complex is a cofactor consisting of four manganese and one calcium metal ions.

It is this cofactor that performs the water splitting reaction, binding the two waters in close proximity to allow them to join together to form a single oxygen molecule. The study reveals how the cofactor is activated, a process that involves the highly regulated uptake of water from its surroundings.

“The study reveals how the enzyme needs to ‘breathe’ to allow water access,” says Dr. Cox. “Half-way through its reaction cycle the enzyme develops the ability to stretch like a concertina. This motion rearranges the atoms that link the manganese centres allowing a single water molecule to bind to the cofactor.”

Importantly, this molecular motion is not accessible at other times during the reaction cycle, preventing water uptake to occur. This then directs the reaction to form a single product, molecular oxygen.

“Without the careful, sequential binding and processing of the two substrate waters, reactive oxygen species can potentially be formed and released which would destroy the whole enzyme,” says MPI CEC researcher Dr. Maria Chrysina.

If human beings could perform the same reaction using cheap materials as nature does, society would have a limitless renewable source of energy.

“Enough sunlight hits the earth in a single hour to power all human activity for about one year,” says Prof. Wolfgang Lubitz, director emeritus at MPI CEC.

The development of artificial water splitting enzymes would provide a means via which society could synthesize ‘solar fuels’, green alternatives to petroleum and natural gas, generated from sunlight and abundant materials such as water.

Hydrogen is one example of a solar fuel, which can be used in transportation, without carbon dioxide emissions that contribute to anthropogenic climate change. It could also aid in the clean, large scale manufacture of other important chemicals such as fertilizers used extensively in agriculture.

This study relies upon a technique called electron paramagnetic resonance (EPR) spectroscopy, which is used to study magnetic materials, such as metals which make up biological cofactors. It allows the electronic structure of a cofactor to be deduced providing important information on how these systems function on a molecular level.

The study was a collaboration between researchers at the Max Planck Institutes for Chemical Energy Conversion (MPI CEC) and Kohlenforschung (MPI KOFO) in Mülheim/Ruhr, Germany, the Ruhr University Bochum in Germany, Uppsala University in Sweden and the Australian National University, Canberra, and was recently published in Proceeding of the National Academy of Sciences of the United States of America:

Chrysina, M., Heyno, E., Kutin, Y., Reus, M., Nilsson, H., Nowaczyk, M. M., DeBeer, S., Neese, F., Messinger, J., Lubitz, W., Cox, N. (2019). Five-coordinate MnIV intermediate in the activation of nature’s water splitting cofactor. Proceedings of the National Academy of Sciences Aug 2019, 201817526; DOI: 10.1073/pnas.1817526116

Prof. Dr. Wolfgang Lubitz
Max Planck Institute for Chemical Energy Conversion
Mülheim/Ruhr
Tel.: +49 (0)208 306 3508
Email wolfgang.lubitz@cec.mpg.de

DOI: 10.1073/pnas.1817526116

https://cec.mpg.de/1/news/

Media Contact

Esther Schlamann Max-Planck-Institut für Chemische Energiekonversion

All latest news from the category: Life Sciences and Chemistry

Articles and reports from the Life Sciences and chemistry area deal with applied and basic research into modern biology, chemistry and human medicine.

Valuable information can be found on a range of life sciences fields including bacteriology, biochemistry, bionics, bioinformatics, biophysics, biotechnology, genetics, geobotany, human biology, marine biology, microbiology, molecular biology, cellular biology, zoology, bioinorganic chemistry, microchemistry and environmental chemistry.

Back to home

Comments (0)

Write a comment

Newest articles

EEG ad tDCS chould serve as the basis of therapeutic strategies to combat newrological disorders. Image Credit: Institute of Science Tokyo

Using Electroencephalography to Improve Language Disorder Treatments

Researchers work towards an inexpensive and portable solution for treating aphasia  Electroencephalography (EEG) may offer a more accessible alternative to functional magnetic resonance imaging (fMRI) for guiding transcranial direct current…

The BioSCape team is poctured with NASA and South African aircraft. Image Credit: Jeremey Shelton/Fishwater Films

Measuring Life on Earth from Space: A Global Research Project

Measurements and data collected from space can be used to better understand life on Earth. An ambitious, multinational research project funded by NASA and co-led by UC Merced civil and…

NEJM study finds patients with blockages in medium-sized vessels in the brain who had endovascular treatment did not do any better and did not see any improvement compared to patients who had the standard of care. Dr. Michael Hill, MD, Dr. Mayank Goyal, MD, PhD (right). Image Credit: Riley Brandt, University of Calgary

Best Approach for Stroke in Medium-Sized Blood Vessels Identified

Calgary’s Stroke Program advancing science to improve care, treatment and outcomes for patients  University of Calgary’s Hotchkiss Brain Institute researchers with the Calgary Stroke Program at Foothills Medical Centre revolutionized…