Inhibition of Na(+)/K(+)-ATPase by 5,6,7,8-tetrafluoro-3-hydroxy-2-phenylquinolin-4(1H)-one.

Na(+)/K(+)-ATPase (NKA) is an enzyme of crucial importance for all animal cells. We examined the inhibitory effects of halogenated phenylquinolinones on NKA. The 5,6,7,8-tetrafluoro-3-hydroxy-2-phenylquinolin-4(1H)-one (TFHPQ) was identified as an efficient NKA inhibitor with IC50 near 10 μM. The inhibition by TFHPQ is particularly efficient at higher concentrations of K(+), where NKA adopts the E2 conformation. The experimental observations are in a good agreement with the outcomes from molecular docking. We identified an energetically favourable TFHPQ binding site for the K(+)-bound NKA, which is located in the proximity of the cytoplasmic C-terminus.