Detection of nucleotide binding to Na,K-ATPase in an aqueous membrane suspension by 13C cross-polarization magic-angle spinning NMR spectroscopy

Binding of uniformly 13C labelled ATP to Na,K-ATPase was studied by 13C cross-polarization magic-angle spinning (CP-MAS) NMR. In the presence of 30 mM Na+ , and with sample- and time-averaging, NMR spectra obtained at 4 °C exhibited several resonances for the bound nucleotide. Chemical shifts suggested that site-specific changes in the micro-environment or conformation of the nucleotide occurred in the high affinity binding site. These experiments permit further studies of nucleotide dynamics, structure and binding under physiologically relevant conditions.