The ultraviolet resonance Raman (UV RR) spectra of functional ATP/membrane-bound Na+K+-ATPase complexes have been obtained. The substrate binding in the enzyme active site has been shown to be accompanied with significant changes in the electronic vibrational structure of the adenine ring. From the spectral analysis of ATP, 8-Br-ATP and 6-NHMe-adenine at various pH values the conclusion was made that N1 and the NH2, group and, probably, N7 of the substrate adenine part, interact with the protein surroundings via hydrogen bonds.
