Validation of surface plasmon resonance screening of a diverse chemical library for the discovery of protein tyrosine phosphatase 1b binders

Abstract

We investigated the suitability of surface plasmon resonance (SPR) for providing quantitative binding information from direct screening of a chemical library on protein tyrosine phosphatase 1b (PTP1B). The experimental design was established from simulations to detect binding with K(D) < 10⁻⁴ M. The 1120 compounds (cpds) were injected sequentially at concentrations [C(cpd)] of 0.5 or 10 μM over various target surfaces. An optimized evaluation procedure was applied. More than 90% of cpds showed no detectable signal in four screens. The 30 highest responders at C(cpd)=10 μM, of which 25 were selected in at least one of three screens at C(cpd)=0.5 μM, contained 22 promiscuous binders and 8 potential PTP1B-specific binders with K(D) ~10⁻⁵ M. Inhibition of PTP1B activity was assayed and confirmed for 6 of these, including sanguinarine, a known PTP1B inhibitor. C(cpd) dependence studies fully confirmed screening conclusions. The quantitative consistency of SPR data led us to propose a structure-activity relationship (SAR) model for developing selective PTP1B inhibitors based on the ranking of 10 arylbutylpiperidine analogs.