The question about how some alkaline enzymes achieve the high rate of proton transfer for hydrogen production has been the subject of speculation in the past. Dr. Martin Winkler, Dr. Jifu Duan, Professor Eckhard Hofmann and Professor Thomas Happe of Ruhr-Universität Bochum (RUB), together with colleagues from Freie Universität Berlin, trace all the proton trail to the operational center of [FeFe]-hydrogenases. Their findings could enable scientists to create stable chemical reproductions of such a biocatalyst efficient, but fragile. The researchers announced their report in the magazine Nature Communication from November 9, 2018.
Unique efficiency due to a transfer route
In their catalytic center, hydrogenases produce molecular hydrogen (H2) of two prototypes and two electrons. They remove the protons needed for this process of neighboring water and transfer them – through a transport chain – to a catalytic core. The exact proton path through hydrogenase did not have to understand so far. "This transfer route is a jigsaw piece, which is essential to understand the expression of a reactor and protein, which is the reason why biocatalists are much more efficient than the chemic complications that produce hydrogen , "explained Dr. Martin Winkler, one of the authors of this study of the Photobiotechnology research group in RUB.
Structures of decoding enzyme variations
In order to calculate which of the hydrogenase-building blocks associated with the transfer of a proton, researchers have been re-assigned individually. I was displaced either by amino acid with a similar function or by a deactive amino acid. Thus, 22 variants of two different hydrogenas were created. Subsequently, the researchers compared those variations in different aspects, including their spectroscopic properties and their enzyme activity. "The molecular structures of twelve proteins, resolved using the X-ray structure analysis, have proved particularly informative," said Winkler.
Amino acids have no function closing hydrogenas
Depending on where and how the researchers had changed the hydrogenase, hydrogen production became less efficient or completely stopped. "So we found out why some variations are seriously damaged in terms of enzyme activity and why other people do not have any fault – against every expectation," said Martin Winkler.
The closest to the catalytic center was the replaced amino acids, the less able the hydrogenase to compensate for these adjustments. If building blocks with no function had been installed in sensitive locations, hydrogen production was closed. "The state produced thus is similar to the over-impulse due to proton stress where protons as well as hydrogen are introduced to the hydrogenase at the same time," elaborates on Martin Winkler. "During our project, for the first time, we were able to stabilize and analyze the remarkably temporary condition that we had already encountered in experiments."
Valid baseline information
This study has made it possible to assign the functions of individual amino acids to the proton transfer pathway for the enzyme group of [FeFe] hydrogenas. "Furthermore, it provides valuable information on the molecular molecular mechanism of proton transfer through retrospective protections and structural requirements," expires Thomas Happe.
The project was funded by the Volkswagen Foundation, the Chinese Scholarship Council, and the German Research Institute under the Resolv Distinction Cluster umbrella (EXC1069).
Materials provided by Ruhr-Bochum University. Originally written by Meike Drießen; Has translated by Donata Zuber. Note: Content may be edited for style and length.