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Long‐Range Electrostatics‐Induced Two‐Proton Transfer Captured by Neutron Crystallography in an Enzyme Catalytic Site |
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| Authors: | Dr. Oksana Gerlits Dr. Troy Wymore Dr. Amit Das Dr. Chen‐Hsiang Shen Dr. Jerry M. Parks Dr. Jeremy C. Smith Dr. Kevin L. Weiss Dr. David A. Keen Dr. Matthew P. Blakeley Dr. John M. Louis Dr. Paul Langan Prof. Irene T. Weber Dr. Andrey Kovalevsky |
| Affiliation: | 1. Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA;2. UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA;3. Solid State Physics Division, BARC, Mumbai, India;4. Departments of Chemistry and Biology, Georgia State University, Atlanta, GA, USA;5. ISIS Facility, Rutherford Appleton Laboratory, Didcot, UK;6. Large-Scale Structures Group, Institut Laue Langevin, Grenoble Cedex 9, France;7. Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, DHHS, Bethesda, MD, USA |
| Abstract: | Neutron crystallography was used to directly locate two protons before and after a pH‐induced two‐proton transfer between catalytic aspartic acid residues and the hydroxy group of the bound clinical drug darunavir, located in the catalytic site of enzyme HIV‐1 protease. The two‐proton transfer is triggered by electrostatic effects arising from protonation state changes of surface residues far from the active site. The mechanism and pH effect are supported by quantum mechanics/molecular mechanics (QM/MM) calculations. The low‐pH proton configuration in the catalytic site is deemed critical for the catalytic action of this enzyme and may apply more generally to other aspartic proteases. Neutrons therefore represent a superb probe to obtain structural details for proton transfer reactions in biological systems at a truly atomic level. |
| Keywords: | aspartic protease enzymes neutron crystallography proton transfer QM/MM modeling |