Towards structure determination of neurotoxin II bound to nicotinic acetylcholine receptor: a solid-state NMR approach (original) (raw)
Solid-state magic-angle spinning nuclear magnetic resonance (NMR) has su⁄cient resolving power for full assignment of resonances and structure determination of immobilised biological samples as was recently shown for a small microcrystalline protein. In this work, we show that highly resolved spectra may be obtained from a system composed of a receptort oxin complex. The NMR sample used for our studies consists of a membrane preparation of the nicotinic acetylcholine receptor from the electric organ of Torpedo californica which was incubated with uniformly 13 C-, 15 N-labelled neurotoxin II. Despite the large size of the ligand^receptor complex ( s 290 kDa) and the high lipid content of the sample, we were able to detect and identify residues from the ligand. The comparison with solution NMR data of the free toxin indicates that its overall structure is very similar when bound to the receptor, but signi¢cant changes were observed for one isoleucine. II; PDSD, proton-driven spin di¡usion; SH3, K-spectrin Src-homology 3 domain FEBS 28219 FEBS Letters 564 (2004) 319^324