In collaboration with Payame Noor University and Iranian Society of Physiology and Pharmacology

Document Type : Article

Authors

1 Associate Professor, Department of Biology, Faculty of Science, Shahrekord University, shahrekord, Iran

2 M. Sc. Student, Department of Biology, Faculty of Science, shahrekord University, shahrekord, Iran

Abstract

Urease (urea amidohydrolase, EC 3.5.1.5) catalyzes the hydrolysis of urea to produce ammonia and CO2. Kinetics studies have been performed using UV-vis spectrophotometer at 40oC and pHs 5.5, 7.2, 8. Result showed that urease inhibition by hydrogen peroxide is a kinetics pH-dependent, such that inhibition is maximal on the condition of pH value 8 while the inhibitory effect hydrogen peroxide at pH 5.5 was minimum. The kinetic parameters Km and Vmax  enzyme obtained from Lineweaver–Burk plot in absence of hydrogen peroxide was 4.52mM and 1.03mM.min-1 respectively .In presence of H2O2, increasing pH leads to decrease Vmax and km. The results showed that in pH 8, boric acid and β-mercaptho ethanol protected urease against hydrogen peroxide. Protectable of β-mercaptho ethanol is more than of boric acid. Such, the results demonstrates that 30 mM boric acid and β-mercaptho ethanol afforded to protect 80% and 90% of urease activity from the loss as compared to the respective control samples

Keywords

Barbara, K.; (2010). Hydrogen peroxide-induced inactivation of urease: Mechanism, kinetics and Inhibitory Potency.; :(2011). Enzymatic 68: 262-269. DOI: 10.1016/j.molcat.2010.11.015.##Barbara, K.; Rudi, E.; (2012). Brindell, Małgorzata (13 August 2012).##Barbara, K.; Stefano, C.; (2005). Jack bean (Canavaliaensi formis) urease Probing acid-base groups of the active site by pH variation.plant physiology and Biochemistry; 43: 651- 658. DOI:10.1016/J.Plaphy-2005.05.009.##Ga-eun, P.; Ha-na, O.; Samyoung, A.; (2009). Improvement of the ammonia analysis by the phenate method in water and wastewater. Bull. korean chem. Soc.; 30(9).##Karplus, P.A.; Pearson, M.A.; Hausinger, R.P.; (1997). 70 years of crystalline urease: What have we learned? Accounts of Chemical Research; 30(8): 330-337.##Martin, P.R.; Hausinger, R.P.; (1992). Site-directed mutagenesis of the active site cysteine in Klebsiella aerogenes urease. The Journal of biological chemistry; 267(28): 20024-7. PMID1400317.##Prakash, O.; Bhushan, G.; (1998). Molecular asymmetry in urease of watermelon (Citrullus vulgaris). J. Plant Biochem. Biotechnol; 7: 50-55.##Prakash, O.; Upadhyay, L.S.B.; (2003). Effect of thiols on the activity of urease from dehusked seeds of watermelon (Citrullus vulgaris). Plant Sci.; 160, 164: 189-194.##Sina, A.; Yagmur, Y.; GÜlay, B.; Adil, D.M.; Yakup, A.; (2002). Reversible immobilization of urease on to procion Brown mx-5BR-Ni(II) attached polyamide hollow-fibre membranes. Process Biochemistry 38(2002)675-683. PII: S0032-9592(02)00198-X.##Sonila, D.; Alqi, C.; (2010). An optimal procedure for ammoniacal nitrogen analysis in natural waters using indophenols Blue method. Podgorica; 9(3): 743-751.##Srivastava, P.K.; Kayastha, A.M.; (2000). Significance of sulhydryl groups in the activity of urease from pigeonpea (Cajanus cajan L.) seeds. Plant Sci.; 519: 539-512.##Stefano, B.; Rypniewski, Wojciech, R.; Wilson Keith, S.; Silvia, M.; Stefano, C.;  Stefano, M.; (1999). A new proposal for urease mechanism based on the crystal structures of the native and inhibited enzyme from Bacillus pasteurii: why urea hydrolysis costs two nickels.##Wiesława, Z.; Barbara, K.; Maciej, L.; Zofia, O.; (2001). Inhibition of urease by Ni2+ ions Analysis of reaction progress curves. Journal of Molecular Catalysis B: Enzymatic; 13: 103-108.##Winterbourn, M.W.; ANAL.; (1967). Phenole-hypochlorite reaction for determination of ammonia. Analytical chemistry; 39: 971-974.##Waldemar, K.; Mirosława, K.; Wiesława, Z.; (2009). 5-Hydroxy-1, 4-naphthoquinone (juglone) and 2-hydroxy-1,4-naphthoquinone (lawsone) influence on jack bean urease activity: Elucidation of the difference in inhibition activity. Bioorganic Chemistry; 38: 132-137.##