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

Abstract

Various inhibitors were tested for their inhibitory effects on soybean urease. The Ki 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 Ki value of 1.30 mM.