The enzymatically inactivated products of kanamycin, paromamine and dihydrostreptomycin have been investigated by proton magnetic resonance at 100MHz in deuterium oxide solution. The low-field shift of resonance position and the coupling constant of P-O-C-H support the previously proposed structures viz kanamycin-3r-phosphate, paromamine-3'-phosphate and dihydrostreptomycin-3''-phosphate, respectively.
