How to Prepare Membrane Proteins for Solid‐State NMR: A Case Study on the α‐Helical Integral Membrane Protein Diacylglycerol Kinase from E. coli

Publisher Website
Google Scholar
Abstract
Several studies have demonstrated that it is viable to use microcrystalline preparations of water‐soluble proteins as samples in solid‐state NMR experiments.1–5 Here, we investigate whether this approach holds any potential for studying water‐insoluble systems, namely membrane proteins. For this case study, we have prepared proteoliposomes and small crystals of the α‐helical membrane‐protein diacylglycerol kinase (DGK). Preparations were characterised by13C‐ and15N‐cross‐polarization magic‐angle spinning (CPMAS) NMR. It was found that crystalline samples produce better‐resolved spectra than proteoliposomes. This makes them more suitable for structural NMR experiments. However, reconstitution is the method of choice for biophysical studies by solid‐state NMR. In addition, we discuss the identification of lipids bound to membrane‐protein crystals by31P‐MAS NMR.