Quantification of protein backbone hydrogen-deuterium exchange rates by solid state NMR spectroscopy |
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Authors: | Juan-Miguel Lopez del Amo Uwe Fink Bernd Reif |
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Institution: | 1.Leibniz-Institut für Molekulare Pharmakologie (FMP),Berlin,Germany;2.Technische Universit?t München (TUM),Garching,Germany;3.Helmholtz-Zentrum München (HMGU), Deutsches Forschungszentrum für Gesundheit und Umwelt,Neuherberg,Germany |
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Abstract: | We present the quantification of backbone amide hydrogen-deuterium exchange rates (HDX) for immobilized proteins. The experiments
make use of the deuterium isotope effect on the amide nitrogen chemical shift, as well as on proton dilution by deuteration.
We find that backbone amides in the microcrystalline α-spectrin SH3 domain exchange rather slowly with the solvent (with exchange
rates negligible within the individual 15N–T
1 timescales). We observed chemical exchange for 6 residues with HDX exchange rates in the range from 0.2 to 5 s−1. Backbone amide 15N longitudinal relaxation times that we determined previously are not significantly affected for most residues, yielding no
systematic artifacts upon quantification of backbone dynamics (Chevelkov et al. 2008b). Significant exchange was observed for the backbone amides of R21, S36 and K60, as well as for the sidechain amides of N38,
N35 and for W41ε. These residues could not be fit in our previous motional analysis, demonstrating that amide proton chemical
exchange needs to be considered in the analysis of protein dynamics in the solid-state, in case D2O is employed as a solvent for sample preparation. Due to the intrinsically long 15N relaxation times in the solid-state, the approach proposed here can expand the range of accessible HDX rates in the intermediate
regime that is not accessible so far with exchange quench and MEXICO type experiments. |
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