T. V. Osadchuk¹, O. V. Shybyryn¹, A. V. Semyroz¹,
O. M. Bondarenko¹, V. K. Kibirev^1,2

¹Institute of Bioorganic Chemistry and Petrochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: osadchuk@bpci.kiev.ua;
²Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv

Furin is the most studied proprotein convertase which processes inactive protein precursors, converting them into biologically active polypeptides. We have investigated cation effects of cesium, strontium, cadmium, iron, cobalt and nickel on the furin activity. It was shown that in the presence of Ca²⁺ (1 mM) these ions were able to activate the enzyme, and the peak position of its activity depends on the nature of the ion. Particularly, for Fe²⁺ it was observed at the ion concentration of 15 mM, whereas for Cd²⁺, Co²⁺ and Ni²⁺ the maximum activity of furin was at 20 mM, for Cs⁺ the peak was at a concentration of 30 mM, and for strontium ions it was 40 mM. The affinity of the cations for furin was estimated by Lineweaver-Burk plots for low concentrations of ions for the ascending branch of furin activity dependence on the cation concentration. It was found that their affinity in comparison with Ca²⁺ was sharply reduced (~ 18-150 times). The studied cations (under physiological conditions) were shown not to be able to compete with calcium ions for furin, and in natural environment they cannot influence its activity.

Keywords: activation, cation effect, furin, furin activity, inhibition