Inhibition of phospholipase A2 by Virasole derivation

Abstract

Kinetics of phosphatidylcholine (PC) hydrolysis under the action of pancreatic phospholipase A2 IB, (EC 3.1.1.4, PLA2) in the presence of a lipophilic derivative of the antiviral drug Virazole 1-(3-((tert-butyldimethylsilyl)oxy)-4-hydroxy-5- (((4-methoxyphenyl)diphenylmethoxy)methyl)tetrahydrofuran-2-yl)-1H-1,2,4-triazole-3-carboxamide (Virazole2ЗГ) was studied. The both steps of phospholipolysis were quantitatively characterized: the binding of the enzyme to the lipid-water interface (Ks) and directly the catalytic act (Km) with the determination of the maximum reaction rate (Vmax). It was found that Virazole2ЗГ at a concentration of 0.5 μmol/ml does not affect the Ks value; on the contrary, the Michaelis constant, Km, increases by a factor of 1.8 along with the constancy of the parameter Vmax. Based on the constancy of the Ks values, it seems to be assumed that there is no inhibition of the disintegration of the enzyme-micelle complex in the presence of the effector under the studied reaction conditions. The kinetic parameters of the reaction (the increase in Km and the constancy of Vmax in the presence of Virazole2ЗГ) testify in favor of a moderate competitive inhibition of pancreatic PLA2, Ki = 65 mM, which indicates the possibility of searching for the biological activity of the anti-pancreatitis action in the series of pro-drugs of nucleoside nature.