Trimethylsilyl tag for probing protein–ligand interactions by NMR
Protein–ligand titrations can readily be monitored with a trimethylsilyl (TMS) tag. Owing to the intensity, narrow line shape and unique chemical shift of a TMS group, dissociation constants can be determined from straightforward 1D 1H-NMR spectra not only in the fast but also in the slow exchange limit. The tag is easily attached to cysteine residues and a sensitive reporter of ligand binding also at sites where it does not interfere with ligand binding or catalytic efficiency of the target protein. Its utility is demonstrated for the Zika virus NS2B–NS3 protease and the human prolyl isomerase FK506 binding protein.
KeywordsDissociation constant Lead discovery Protein–ligand interactions Slow exchange Trimethylsilyl group
We thank Mr Mithun Chamikara Mahawaththa for mass spectrometry measurements and Professor Rolf Hilgenfeld for providing a sample of the substrate Bz-Nle-Lys-Lys-Arg-AMC. C.N. and G.O. thank the Alexander von Humboldt Foundation for a Feodor Lynen Fellowship and the Australian Research Council for a Laureate Fellowship, respectively. Financial project support by the Australian Research Council, the Austrian Science Fund (FWF) (DK Molecular Enzymology W901 to K.Z.) and by NAWI Graz is gratefully acknowledged.
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