Inhibition studies of soybean (Glycine max) urease with heavy metals,sodium salts of mineral acids,boric acid,and boronic acids

Various inhibitors were tested for their inhibitory effects on soybean urease. The K_i values for boric acid, 4-bromophenylboronic acid, butylboronic acid, and phenylboronic acid were 0.20?±?0.05?mM, 0.22?±?0.04?mM, 1.50?±?0.10?mM, and 2.00?±?0.11?mM, respectively. The inhibition was competitive type with boric acid and boronic acids. Heavy metal ions including Ag⁺, Hg²⁺, and Cu²⁺ showed strong inhibition on soybean urease, with the silver ion being a potent inhibitor (IC₅₀ = 2.3?×?10^?8 mM). Time-dependent inhibition studies exhibited biphasic kinetics with all heavy metal ions. Furthermore, inhibition studies with sodium salts of mineral acids (NaF, NaCl, NaNO₃, and Na₂SO₄) showed that only F^? inhibited soybean urease significantly (IC₅₀ = 2.9?mM). Competitive type of inhibition was observed for this anion with a K_i value of 1.30?mM.