Neutron diffraction analysis studies reported an isolated hydronium ion (H3O+) in the interior of D-xylose isomerase (XI) and phycocyanobilin-ferredoxin oxidoreductase (PcyA). H3O+ forms hydrogen bonds (H-bonds) with two histidine side-chains and a backbone carbonyl group in PcyA, whereas H3O+ forms H-bonds with three acidic residues in XI. Using a quantum mechanical/molecular mechanical (QM/MM) approach, we analyzed stabilization of H3O+ by the protein environment. QM/MM calculations indicated that H3O+ was unstable in the PcyA crystal structure, releasing a proton to an H-bond partner His88, producing H2O and protonated His88. On the other hand, H3O+ was stable in the XI crystal structure. H-bond partners of isolated H3O+ would be practically limited to acidic residues such as aspartic and glutamic acids in the protein environment.
Transient Access to the Protein Interior: Simulation Versus NMR
Transient Access to the Protein Interior: Simulation Versus NMR
Publication date: 28 January 2014
Source:Biophysical Journal, Volume 106, Issue 2, Supplement 1</br>
Author(s): Filip Persson , Bertil Halle</br>
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Transient Access to the Protein Interior: Simulation versus NMR
Transient Access to the Protein Interior: Simulation versus NMR
Filip Persson and Bertil Halle
http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/0/jacsat.ahead-of-print/ja403405d/aop/images/medium/ja-2013-03405d_0009.gif
Journal of the American Chemical Society
DOI: 10.1021/ja403405d
http://feeds.feedburner.com/~ff/acs/jacsat?d=yIl2AUoC8zA
http://feeds.feedburner.com/~r/acs/jacsat/~4/c6S7B-kGEWU
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Abstract
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