Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Neutrons observe vitamin B6-dependent enzyme activity useful for drug development

17.10.2017

Scientists at the Department of Energy's Oak Ridge National Laboratory have performed neutron structural analysis of a vitamin B6-dependent protein, potentially opening avenues for new antibiotics and drugs to battle diseases such as drug-resistant tuberculosis, malaria and diabetes.

Specifically, the team used neutron crystallography to study the location of hydrogen atoms in aspartate aminotransferase, or AAT, an enzyme vital to the metabolism of certain amino acids.


An ORNL-led team used neutrons to observe the AAT enzyme, a vitamin B6-dependent protein, and found that the chemical reaction occurred only in one active site. Nuclear scattering length density maps (colored mesh) highlight the positions of critical hydrogen atoms, including a low-barrier hydrogen bond (magenta mesh) not thought to exist in AAT, which may be crucial for catalysis.

Credit: Jill Hemman and Andrey Kovalevsky /Oak Ridge National Laboratory, US Dept. of Energy

"We visualized the first neutron structure of a vitamin B6 enzyme that belongs to a large protein family with hundreds of members that exist in nature," said ORNL's Andrey Kovalevsky, a senior co-author of the study, which was published in Nature Communications.

Vitamin B6-dependent proteins are part of a diverse group of enzymes that conduct over a hundred different chemical reactions in cells. The enzymes are of interest to biomedical, as well as bioenergy, researchers because of their role in metabolizing amino acids and other cell nutrients.

"These enzymes are unique in that each one performs a specific chemical reaction with exquisite accuracy, while suppressing other viable chemical transformations," Kovalevsky said. "How they accomplish this is not well understood, but it is of great significance for drug design."

The team's previous research predicted that hydrogen atoms move in and around the enzyme's active site, where the chemical reaction takes place, indicating that the hydrogen atoms' positioning controls the reaction type. Knowing the precise location of hydrogen atoms can explain why the behavior of these enzymes is so specific, but hydrogen is hard to detect with standard methods such as X-ray crystallography.

To directly determine the positions of hydrogen atoms within AAT, the ORNL-led team turned to neutron diffraction techniques. The researchers exposed delicate protein crystals to neutrons using the IMAGINE beamline at ORNL's High Flux Isotope Reactor and the LADI-III beamline at the Institut Laue-Langevin in Grenoble, France.

Surprisingly, the team observed a reaction within one AAT protein biomolecule while another AAT biomolecule was unchanged, providing a before-and-after perspective of the enzyme-catalyzed chemical reaction.

"The data revealed that in one of the enzyme's biomolecular structures the covalent bonds reorganized after a chemical reaction occurred in the active site and, in another, the reaction had not taken place," Kovalevsky said. "Essentially, we were able to obtain two structures in one crystal, which has never been done before for any protein using neutrons."

With this knowledge, the team will run molecular simulations to determine the hydrogen atoms' specific behavior when interacting with the enzyme. The results could be useful in guiding the future design of novel medicines against multidrug-resistant tuberculosis, malaria, diabetes and antibiotic-resistant bacteria.

"This study highlights how neutrons are an unrivaled probe for identifying the location of hydrogen atoms in biological systems, providing us with an unprecedented level of structural detail for this important enzyme," LADI-III beamline scientist Matthew Blakeley said.

###

The neutron crystallography study, titled "Direct visualization of critical hydrogen atoms in a pyridoxal 5'- phosphate enzyme," included co-authors Steven Dajnowicz of ORNL and the University of Toledo; ORNL's Andrey Kovalevsky, Jerry Parks, Ryne C. Johnston and Kevin L. Weiss; Matthew P. Blakeley of the Institut Laue Langevin; David A. Keen of Rutherford Appleton Laboratory; Oksana Gerlits of the University of Tennessee, and Timothy C. Mueser of the University of Toledo.

Steven Dajnowicz, the paper's lead co-author and a doctoral student at the University of Toledo, works in ORNL's Biology and Soft Matter Division as part of ORNL's Graduate Opportunities (GO!) student program. Mueser is Dajnowicz' advisor and a senior co-author of the paper.

This project was funded by DOE's Office of Science and used resources at ORNL's Center for Structural Molecular Biology. Neutron crystallography work was performed at ORNL's HFIR, a DOE Office of Science User Facility, and at the Institut Laue-Langevin. This work also used ORNL's Compute and Data Environment for Science for quantum mechanical calculations. This project was also supported in part by the Center for the Advancement of Science in Space and the National Aeronautics and Space Administration.

ORNL is managed by UT-Battelle for the Department of Energy's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. DOE's Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov.

Media Contact

Sara Shoemaker
shoemakerms@ornl.gov
865-576-9219

 @ORNL

http://www.ornl.gov 

Sara Shoemaker | EurekAlert!

More articles from Life Sciences:

nachricht Bacteria as pacemaker for the intestine
22.11.2017 | Christian-Albrechts-Universität zu Kiel

nachricht Researchers identify how bacterium survives in oxygen-poor environments
22.11.2017 | Columbia University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Nanoparticles help with malaria diagnosis – new rapid test in development

The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.

Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Corporate coworking as a driver of innovation

22.11.2017 | Business and Finance

PPPL scientists deliver new high-resolution diagnostic to national laser facility

22.11.2017 | Physics and Astronomy

Quantum optics allows us to abandon expensive lasers in spectroscopy

22.11.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>