Mapping the bound conformation and protein interactions of microtubule destabilizing peptides by STD–NMR spectroscopy

Using the hemiasterlin analogs taltobulin (I, HTI-286), II, and III as model compounds, we demonstrate that relaxation-compensated STD–NMR can be used as an effective tool to efficiently provide a qualitative epitope map for microtubule destabilizing peptides. Due to the disparate relaxation behavior of the protons in these model compounds, it was essential to collect STD with very short saturation times to render an accurate picture of the binding interaction. The conformation of HTI-286 (I) in complex with the protein was determined from TRNOESY/ROESY experiments and is similar to the X-ray crystal structure conformation observed for hemiasterlin methyl ester in the absence of protein.