The interaction between protein kinase CK2 and polylysine has been studied by Surface Plasmon Resonance (SPR). The binding process has a very low energy of activation, it is irreversible, and too slow as to explain the enzyme activity stimulation as a direct consequence of the polylysine binding. The polylysine interaction with a peptide substrate and with casein are faster, and in agreement with a substrate-mediated mechanism of activity stimulation. After several hours of incubation, the binding of polylysine to CK2 produces the loss of enzymatic activity.