Mechanism understanding of PIKfyve inhibitor YM201636 with human serum albumin: Insights from molecular modeling and multiple spectroscopic techniques.

YM201636 is the potent PIKfyve inhibitor that is being actively investigated for liver cancer efficacy. In this study, computer simulations and experiments were conducted to investigate the interaction mechanism between YM201636 and the transport protein HSA. Results indicated that YM201636 is stably bound between the subdomains IIA and IIIA of HSA, supported by site marker displacement experiments. YM201636 quenched the endogenous fluorescence of HSA by static quenching since a decrease in quenching constants was observed from 7.74 to 2.39 × 10 M. UV-vis and time-resolved fluorescence spectroscopy confirmed the YM201636-HSA complex formation and this binding followed a static mechanism. Thermodynamic parameters ΔG, ΔH, and ΔS obtained negative values suggesting the binding was a spontaneous process driven by Van der Waals interactions and hydrogen binding. Binding constants ranged between 5.71 and 0.33 × 10 M, which demonstrated a moderately strong affinity of YM201636 to HSA. CD, synchronous, and 3D fluorescence spectroscopy revealed that YM201636 showed a slight change in secondary structure. The increase of K and a decrease of PSH with YM201636 addition showed that YM201636 changed the surface hydrophobicity of HSA. The research provides reasonable models helping us further understand the transportation and distribution of YM201636 when it absorbs into the blood circulatory system.