Hong, Iowa State's John D. Corbett Professor of Chemistry and an associate scientist for the U.S. Department of Energy's Ames Laboratory, said the findings clarify previous, conflicting studies and should pave the way to development of new antiviral drugs against influenza viruses, including pandemic H1N1.
Two papers published by Nature in 2008 came to different conclusions about where the antiviral drug amantadine binds to a flu virus and stops it from infecting a healthy cell. A paper based on X-ray studies concluded the drug attached to the lumen of the proton channel, the area inside the channel, and stopped the virus by blocking the channel. Another paper based on solution nuclear magnetic resonance (NMR) technology concluded the drug attached to the surface of the virus protein near the proton channel and stopped the virus by indirectly changing the channel structure.
Hong's research concluded that when amantadine is present at the pharmacologically relevant amount of one molecule per channel, it attaches to the lumen inside the proton channel. But the paper also reports that when there are high concentrations of amantadine in the membrane, the drug will also attach to a second site on the surface of the virus protein near the channel.
"Our study using solid-state NMR technology unequivocally shows that the true binding site is in the channel lumen, while the surface-binding site is occupied only by excess drug," Hong said. "The previous solution NMR study used 200-fold excess drug, which explains their observation of the surface-binding site. The resolution of this controversy means that medical chemists can now try to design new drugs to target the true binding site of the channel."
Here's how a flu virus uses its proton channel and how amantadine blocks that channel:
The virus begins an infection by attaching itself to a healthy cell. The healthy cell surrounds the flu virus and takes it inside the cell through a process called endocytosis. Once inside the cell, the virus uses a protein called M2 to open a channel to the healthy cell. Protons from the healthy cell flow through the channel into the virus and raise its acidity. That triggers the release of the virus' genetic material into the healthy cell. The virus hijacks the healthy cell's resources and uses them to reproduce and spread.
When amantadine binds to and blocks the M2 proton channel, the process doesn't work and a virus can't infect a cell and spread.
Hong and the research team developed powerful techniques to study the proton channel using solid-state NMR spectroscopy, the technology behind medical magnetic resonance imaging. The techniques provided the researchers with a detailed look at the antiviral drug within the proton channel, showed them the structure of the protein at the drug-binding site and allowed them to make accurate measurements of the distances between the drug and the protein.
The researchers also found that amantadine spins when it binds to the inside of the proton channel. That means it doesn't fill the channel. And Hong said that leaves room for development of other drugs that do a better job blocking the channel, stopping the flu and evading development of drug resistance.
Other contributors to the study are Klaus Schmidt-Rohr, an Iowa State professor of chemistry and a senior chemist for the Ames Laboratory; Sarah Cady, a postdoctoral research associate in Iowa State's chemistry department; William DeGrado, the George W. Raiziss Professor of Biochemistry and Biophysics and adjunct professor of chemistry at the University of Pennsylvania; Cinque S. Soto, a postdoctoral researcher in the University of Pennsylvania's department of biochemistry and biophysics; and Jun Wang, a graduate student in the University of Pennsylvania's department of chemistry.
The research project was supported by grants of $687,411 from the National Science Foundation and $616,295 from the National Institutes of Health.
Mei Hong | EurekAlert!
Ambush in a petri dish
24.11.2017 | Friedrich-Schiller-Universität Jena
Meadows beat out shrubs when it comes to storing carbon
23.11.2017 | Norwegian University of Science and Technology
High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons
The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
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....
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...
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...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
24.11.2017 | Physics and Astronomy
24.11.2017 | Health and Medicine
24.11.2017 | Earth Sciences