Biochemical Studies on Urease From Pumpkin (Cucurbita Moschata)

Abstract

Urease was ·extracted from the dehusked seeds of pumpkin (C. moschata). The enzyme was stored at two different temperature 4 °C and 3 7 °C and it was found that the selflife (t112) was 70 days at 4 oc where as it was 12 days at 37 °C. Under steady state kinetics, the optimum p~ and optimum temperature were found to be 8.4 and 80 oc respectively. The value of Km and Vmax were 12.50 mM and 62.50 ~mol/min, respectively. Furthermore, urease was assayed in presence of various compounds to explore the potential inhibitors. The ! 50 value for boric acid inhibition was found 7.5 mM. The value of inhibition constant (K;) was found to ~e 2.50 mM and the competitive type of inhibition was recorded. Further, !50 value for Cu2+ was 4.0x10"3 mM. The !so values for Hg2 + were recorded at 4.8x10-4 mM revealing its highest inhibition potency. Based on the values of inhibition constant Ki the heavy-metal ions·were found to inhibit urease in the following order Hg2 + > Cu2 +. The inhibition studies are important as elevated levels of soil/ microbial ureases have been known to decrease the efficiency ofurea fertilizer. It is well known that low concentration of inhibitors could inhibit the urease activity in soil. Thus such studies may have medical or agronomic importance, as well as provide insight into the urease catalytic mechanism.