. | . |
Neutrons probe oxygen-generating enzyme for a greener approach to clean water by Staff Writers Oak Ridge TN (SPX) Nov 20, 2017
A new study sheds light on a unique enzyme that could provide an eco-friendly treatment for chlorite-contaminated water supplies and improve water quality worldwide. An international team of researchers led by Christian Obinger from the University of Vienna used neutron analysis at Oak Ridge National Laboratory, x-ray crystallography and other techniques to study the chlorite dismutase enzyme. This naturally occurring protein can break down chlorite, an industrial pollutant found in groundwater, drinking water and soils, into harmless byproducts, but its catalytic process is not well understood. Understanding how the bacterial enzyme converts chlorite into chloride and oxygen could open possibilities for future applications in bioremediation and biotechnology. The results, published in ACS Catalysis, also contribute to fundamental research on the enzyme's ability to produce oxygen. Oxygen generation is incredibly rare in nature, once thought possible only by photosynthesis, so the enzymatic activity of chlorite dismutase has attracted interest from the scientific community beyond its environmental applications for clean water. Exactly how chlorite dismutase works at a molecular level to break down chlorite has been debated since the enzyme was discovered in 1996. The complexity of the enzyme's molecular structure and the difficulty of studying proteins with experimental methods present inherent challenges for researchers. Like most enzymes, chlorite dismutase is a protein that catalyzes a highly specific reaction. The process is often environmentally dependent, meaning it works best within specific parameters, including temperature, concentration and pH ranges. Identifying the ideal parameters for the reaction is key to supporting bioengineering and large-scale production of chlorite dismutase to safely remove chlorite from the environment and potentially exploit the enzyme's oxygen generation. The team isolated an unstudied Cyanothece strain of chlorite dismutase and examined the protein's crystal structure at specific pH values to determine the impact of pH on chlorite conversion. The researchers used MaNDi, the macromolecular neutron diffractometer, beamline 11-B at the Spallation Neutron Source, a Department of Energy User Facility at ORNL, to collect unique data only obtainable through the use of neutrons. "Different protein crystals have different degrees of symmetry, which will determine how we go about measuring them. This crystal is unusual in that it has very little symmetry, so an especially large number of reflections have to be recorded individually to get a complete data set," said Leighton Coates, MaNDi Lead Instrument Scientist. "This would be a challenging and lengthy task anywhere, and it was only achievable in this time frame due to the large area detector coverage of the MaNDi instrument." On MaNDi, researchers were able to detect the protonation states of important amino acids thought to support the reaction. "Protonation" refers to a fundamental step in catalysis during which hydrogen attaches to molecules. "This is the important region of the protein, where the chemistry is happening and the chlorite is being broken down," said Coates. Protonation states are not easily observed because they involve hydrogen, which is difficult to detect with x-rays or other techniques. In addition, a phenomenon called "photoreduction" occurs when exposing metal-containing enzymes like chlorite dismutase to x-rays, essentially changing the atomic structure of the sample. Because neutron techniques do not have these limitations, they can give researchers key information that cannot be obtained by other methods. "Neutrons are nondestructive and sensitive to light elements like hydrogen, so they can provide exclusive information about the atomic structure of proteins, which are largely composed of hydrogen molecules," Coates explained. "And unlike x-rays that can damage delicate proteins, neutron techniques allow you to collect data at room temperature on an unaltered protein in its active state without the impacts of ionizing radiation and photoreduction," said Coates. "This experiment really highlights the benefit of using neutrons to study proteins." The journal article is published as "Molecular mechanism of enzymatic chlorite detoxification: insights from structural and kinetic studies." Coauthors include Irene Schaffner, Georg Mlynek, Nicola Flego, Dominic Puhringer, Julian Libiseller-Egger, Leighton Coates, Stefan Hofbauer, Marzia Bellei, Paul G. Furtmu?ller, Gianantonio Battistuzzi, Giulietta Smulevich, Kristina Djinovic-Carugo and Christian Obinger.
Gao, Mali (AFP) Nov 7, 2017 Among the lines of small mud houses, plastic litter and piles of parched earth, children gaze skywards at a shiny blue tank perched on steel legs. It holds a vital resource of which they have been deprived for years: water. In a world where more than a billion people lack access to water, residents of this dusty corner of Gao, the main city in Mali's sprawling arid north, know the terrif ... read more Related Links Oak Ridge National Laboratory Water News - Science, Technology and Politics
|
|
The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us. |