Fig 1.
Ertiprotafib is a non-competitive inhibitor of PTP1B.
(a) Chemical structure of Ertiprotafib. Michaelis-Menten kinetics of (b) PTP1B1-301 and (c) PTP1B1-393 as a function of Ertiprotafib concentration using pNPP as substrate. Note the decrease in activity of PTP1B as a function of Ertiprotafib concentration. Lineweaver–Burk plot of (d) PTP1B1-301and (e) PTP1B1-393 showing the mode of Ertiprotafib inhibition.
Table 1.
Turnover rates (kcat) and catalytic efficiencies (kcat/Km) of PTP1B in the presence of Ertiprotafib.
Fig 2.
Ertiprotafib binds PTP1B non-specifically and induces its aggregation.
Overlay of the 2D [1H,15N]-TROSY spectra of (a) PTP1B1-301 and (c) PTP1B1-393 in the presence of ten and fifteen, respectively, molar equivalents of Ertiprotafib showing the near-complete disappearance of the peaks from the structured regions. (b) Chemical shift (top panel) and intensity (middle panel, colored in blue) changes of Ertiprotafib binding (at a molar ratio of 10) to PTP1B residues 301–393, illustrating the non-specific interaction of C-terminal disordered region much like another allosteric inhibitor, MSI-1436. Colored lines indicate one (blue), two (green) and three (yellow) s.d. from the mean CSPs. Note the large increase in intensities of the peaks of the C-terminal disordered regions at higher molar ratios of Ertiprotafib (15 molar excess, bottom panel, colored in orange).
Fig 3.
Oligomerization of PTP1B is dependent on Ertiprotafib concentration.
Changes in RH of (a) PTP1B1-393 (black) and (b) PTP1B1-301 (red) as a function of increasing Ertiprotafib concentration as measured by Dynamic light scattering experiments. Note the increase in RH at higher Ertiprotafib concentrations confirms PTP1B aggregation. Melting temperatures (Tm) of (c) PTP1B1-393 (black) and (d) PTP1B1-301 (red) as a function of Ertiprotafib concentration.