Acetonitrile allows indirect replacement of non-deuterated lipid detergents by deuterated lipid detergents for the NMR study of detergent-soluble proteins

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Acetonitrile allows indirect replacement of non-deuterated lipid detergents by deuterated lipid detergents for the NMR study of detergent-soluble proteins

Abstract

Detergent-soluble proteins (DSPs) are commonly dissolved in lipid buffers for NMR experiments, but the huge lipid proton signal prevents recording of high-quality spectra. The use of costly deuterated lipids is thus required to replace non-deuterated ones. With conventional methods, detergents like dodecylphosphocholine (DPC) cannot be fully exchanged due to their high binding affinity to hydrophobic proteins. We propose an original and simple protocol which combines the use of acetonitrile, dialysis and lyophilization to disrupt the binding of lipids to the protein and allow their indirect replacement by their deuterated equivalents, while maintaining the native structure of the protein. Moreover, by this protocol, the detergent-to-protein molar ratio can be controlled as it challenges the protein structure. This protocol was applied to solubilize the Vpx protein that was followed upon addition of DPC-d38 by 1H-15N SOFAST-HMQC spectra and the best detergent-to-DSPs molar ratio was obtained for structural studies.

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