THE EFFECT OF CALIXARENE C-107 ON KINETIC PARAMETERS OF Nа+,К+-АТРase
OF UTERUS MYOCYTE PLASMA MEMBRANE
1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
2Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kyiv;
The inhibitory action of calixarene C-107 (5,17-diamino(2-pyridyl)methylphosphono-11,23-di-tret-butyl-26,28-dihydroxy-25,27-dipropoxycalixarene) on Na+,K+-ATPase activity kinetic properties of myometrium perforated plasma membrane was investigated. It has been shown that the calixarene C-107 inhibiting Na+,K+-ATPase does not change the kinetic parameters (Km, nH) of reaction velocity dependence on substrate concentration. The constant Кa of enzyme activation by MgCl2 has complex dependence on calixarene C-107 concentration: it increases twice with growth of calixarene concentration up to 50 nM and decreases to the control level with further growth of calixarene concentration. The Hill cooperativity coefficient nH of activation by MgCl2 does not vary in the presence of calixarene C-107. Both ATP and MgCl2 have no influence on Na+,K+-АТРase constant of inhibition by calixarene C-107, but an increase of concentration of the mentioned physiological compounds causes the growth of cooperativity coefficient nH of enzymatic reaction inhibition by calixaren C-107.
Key words: calixarene, Nа+,K+-АТРase, plasmatic membrane, smooth muscle cells, myometrium, kinetic properties of АТРase.
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