Cisplatin is the most widely used chemotherapeutic drug for the treatment of various types of cancer; however, its administration brings also numerous side effects. It was demonstrated that cisplatin can inhibit the Na+/K+-ATPase (NKA), which can explain a large part of the adverse effects. In this study, we have identified five cysteinyl residues (C452, C456, C457, C577, and C656) as the cisplatin binding sites on the cytoplasmic loop connecting transmembrane helices 4 and 5 (C45), using site-directed mutagenesis and mass spectrometry experiments. The identified residues are known to be susceptible to glutathionylation indicating their involvement in a common regulatory mechanism.

• Klíčová slova
• C45 loop, Na+/K+-ATPase, binding site, cisplatin, cysteine mutants, sodium pump,
• MeSH
• cisplatina chemie   farmakologie   MeSH
• cystein antagonisté a inhibitory   metabolismus   MeSH
• cytoplazma účinky léků   metabolismus   MeSH
• hmotnostní spektrometrie MeSH
• mutageneze cílená MeSH
• myši MeSH
• protinádorové látky chemie   farmakologie   MeSH
• simulace molekulární dynamiky MeSH
• sodíko-draslíková ATPasa antagonisté a inhibitory   genetika   metabolismus   MeSH
• vazebná místa účinky léků   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• cisplatina MeSH
• cystein MeSH
• protinádorové látky MeSH
• sodíko-draslíková ATPasa MeSH

We examined the inhibitory effects of three flavonolignans and their dehydro- derivatives, taxifolin and quercetin on the activity of the Na(+)/K(+)-ATPase (NKA). The flavonolignans silychristin, dehydrosilychristin and dehydrosilydianin inhibited NKA with IC50 of 110 ± 40 μM, 38 ± 8 μM, and 36 ± 14 μM, respectively. Using the methods of molecular modeling, we identified several possible binding sites for these species on NKA and proposed the possible mechanisms of inhibition. The binding to the extracellular- or cytoplasmic C-terminal sites can block the transport of cations through the plasma membrane, while the binding on the interface of cytoplasmic domains can inhibit the enzyme allosterically. Fluorescence spectroscopy experiments confirmed the interaction of these three species with the large cytoplasmic segment connecting transmembrane helices 4 and 5 (C45). The flavonolignans are distinct from the cardiac glycosides that are currently used in NKA treatment. Because their binding sites are different, the mechanism of inhibition is different as well as the range of active concentrations, one can expect that these new NKA inhibitors would exhibit also a different biomedical actions than cardiac glycosides.

• Klíčová slova
• Na+/K+-ATPase, binding sites, flavonolignans, inhibition, sodium pump,
• Publikační typ
• časopisecké články MeSH

• MeSH
• biosenzitivní techniky přístrojové vybavení   metody   MeSH
• elektrochemické techniky přístrojové vybavení   metody   MeSH
• glykomika přístrojové vybavení   metody   MeSH
• glykoproteiny analýza   metabolismus   MeSH
• lidé MeSH
• molekulární modely MeSH
• molekulární sekvence - údaje MeSH
• proteiny analýza   metabolismus   MeSH
• sacharidové sekvence MeSH
• sekvence aminokyselin MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• glykoproteiny MeSH
• proteiny MeSH