Demonstration of different complexation modes between cobalt and 5' AMP, by direct NMR observation of the low-temperature complex

We report the first direct NMR observation of transition metal-nucleotide complexes. The phosphorus and proton spectra of a cobalt-5' AMP complex were observed in water, pH 7, -- 10 degrees C. This complex is different from the high temperature species : for instance its 31P chemical shift is -- 50 ppm, whereas the published value obtained indirectly for the high temperature form corresponds to ca. -- 1200 ppm. The -- 50 ppm complex is present in significant proportion at 20 degrees C and possibly at higher temperatures. Multiple complexation modes are also observed for Co-ATP.