Konformationeller Austausch eines Liganden in der Bindetasche eines Proteins auf der Mikrosekundenzeitskala

Abstract

The possible internal dynamics of non‐isotope‐labeled small‐molecule ligands inside a target protein is inherently difficult to capture. Whereas high crystallographic temperature factors can denote either static disorder or motion, even moieties with very low B‐factors can be subject to vivid motion between symmetry‐related sites. Here we report the experimental identification of internal µs timescale dynamics of a high‐affinity, natural‐abundance ligand tightly bound to the enzyme human carbonic anhydrase II (hCAII) even within a crystalline lattice. The rotamer jumps of the ligand’s benzene group manifest themselves both, in solution and fast magic‐angle spinning solid‐state NMR 1H R1ρ relaxation dispersion, for which we obtain further mechanistic insights from molecular‐dynamics (MD) simulations. The experimental confirmation of rotameric jumps in bound ligands within proteins in solution or the crystalline state may improve understanding of host‐guest interactions in biology and supra‐molecular chemistry and may facilitate medicinal chemistry for future drug campaigns.