A group of Japanese researchers have made a significant breakthrough by identifying the mechanism for controlling the potential of a protein that carries electrons in redox reactions essential for energy production in all organisms. Their research has been published in the online publication Elife.
The researchers were able to determine the exact three-dimensional structure of the protein, including the position of hydrogen atoms. By using this information, they conducted theoretical calculations that allowed them to visualize the electronic structure of the iron-sulfur cluster. It was discovered that the electrical potential of the cluster can be greatly altered by the presence or absence of a single hydrogen atom on an amino acid side chain, leading to what is described as a “nano-switch” mechanism.
These findings not only advance our understanding of biological reactions but also have potential applications in the development of highly sensitive oxygen and nitrogen oxide sensors, as well as new drug discovery.
Redox reactions, involving the transfer of electrons, are crucial for many biological processes such as respiration and photosynthesis. Some proteins responsible for electron transfer contain iron and sulfur, with ferredoxin being a universal carrier of electrons found in almost all living organisms. However, the exact mechanism of electron transfer by ferredoxin has long been a mystery.
As part of their study, the researchers utilized the IBIX crystal diffractometer at the J-PARC complex in Japan to determine the atomic-level structure of ferredoxin using a neutron beam. Visualizing hydrogen atoms in proteins with neutrons is a challenging task, as less than 0.2% of proteins in the three-dimensional structure database contain such data.
By combining experimental data with calculations, the researchers were able to uncover the electronic structure of the iron-sulfur ferredoxin cluster. They found that the presence of asparagine at a distance from the cluster significantly influences electron transfer, acting as a switch mechanism. This mechanism was shown to be universal across different organisms.