[Binding activity of polypeptide containing human Na+, K+-ATPase alpha1 subunit M1-M2 extracellular segment].

Objective: To assess the binding activity of polypeptide containing human Na+, K+-ATPase alpha1 subunit M1-M2 extracellular segment (HES1 derivative).

Methods: HES1 derivative was synthesized by Fmoc method and purified by high-performance liquid chromatography-mass spectrometry, and its binding activity was identified by radioligand binding assay.

Results: 3H-ouabain and synthetic HES1 derivative showed some binding activity with the equilibrium dissociation constant (KD) of 24.58 nmol/L, with the the receptor density of 492.43 fmol x mg(-1) pro. and IC50 of 3.078 x 10(-7) mol/L.

Conclusion: HES1 derivative can bind to ouabain and has the potential of becoming an effective therapeutic agent.