Inhibition assays of free and immobilized urease for detecting hexavalent chromium in water samples
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The present work describes the inhibition studies of free as well as immobilized urease by different heavy metals. Porous silicon (PS) films prepared by electrochemical etching were used for urease immobilization by physical adsorption. The enzyme was subjected to varying concentrations of Cr6+, Cr3+, Cu2+, Fe2+, Cd2+ and Ni2+ and analyzed for the variation in the activity. To study the effect of other heavy metals on the interaction of urease and Cr6+, free as well as immobilized urease was subjected to the combination of each metal ion with Cr6+. Results proved the sensitivity of free as well as immobilized urease towards heavy metals by observed reduction in activity. Immobilized urease showed less degree of inhibition compared to free urease when tested for inhibition by individual metal ions and in combination with Cr6+. IC50 values were found higher for inhibition by the combination of metal ions with Cr6+. Interaction of heavy metal ions with functional groups in active site of urease and limitations of mass transfer are the two factors responsible for the variation in activity of urease. Relation between the variation of urease activity and amount of heavy metals can be applied in biosensor development for determining the concentration of Cr6+ present in the water samples.
KeywordsUrease Immobilization Porous silicon Chromium Heavy metals Urease inhibition
The authors gratefully acknowledge the Department of Science and Technology (DST), India for funding the research under DST-WTI (Water Technology Initiative) (WTI/2015/113). The authors thank the Department of Biotechnology and Medical Engineering and the Department of Electrical Engineering of National Institute of Technology Rourkela, India for providing the research facility.
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Conflict of interest
The authors declare no conflict of interest to disclose.
- Moyo M, Okonkwo JO, Agyei NM (2014) An amperometric biosensor based on horseradish peroxidase immobilized onto maize tassel-multi-walled carbon nanotubes modified glassy carbon electrode for determination of heavy metal ions in aqueous solution. Enzyme Microb Technol 56:28–34. https://doi.org/10.1016/J.ENZMICTEC.2013.12.014 CrossRefPubMedGoogle Scholar
- Pan L, Wang C, Yan K, Zhao K, Sheng G, Zhu H, Zhao X, Qu D, Niu F, You Z (2016) Synthesis, structures and Helicobacter pylori urease inhibitory activity of copper(II) complexes with tridentate aroylhydrazone ligands. J Inorg Biochem 159:22–28. https://doi.org/10.1016/j.jinorgbio.2016.02.017 CrossRefPubMedGoogle Scholar
- Saleem M, Rafiq M, Seo S-Y, Lee KH (2016) Acetylcholinesterase immobilization and characterization, and comparison of the activity of the porous silicon-immobilized enzyme with its free counterpart. Biosci Rep 36:e00311–e00311. https://doi.org/10.1042/BSR20150154 CrossRefPubMedPubMedCentralGoogle Scholar
- Vaidya AM, Annapure US (2019) Enzymes in biosensors for food quality assessment. Enzym Food Biotechnol 32:659–674. https://doi.org/10.1016/B978-0-12-813280-7.00038-4 CrossRefGoogle Scholar
- Wieczorek K, Wyszkowska J, Kucharski J (2015) Sensitivity of soil urease to soil contamination by zinc, copper, nickel, cadmium and lead. Fresenius Environ Bull 24:2496–2504Google Scholar
- Zheng M, Zhu J, Huang F, Xiang X, Shi J, Deng Q, Ma F, Feng Y (2015b) Enzymatic deacidification of the rice bran oil and simultaneous preparation of phytosterol esters-enriched functional oil catalyzed by immobilized lipase arrays. RSC Adv 5:70073–70079. https://doi.org/10.1039/C5RA11533G CrossRefGoogle Scholar
- Zhou Y, Li Y-S, Tian X-L, Zhang Y-Y, Yang L, Zhang J-H, Wang X-R, Lu S-Y, Ren H-L, Liu Z-S (2012) Enhanced ultrasensitive detection of Cr(III) using 5-thio-2-nitrobenzoic acid (TNBA) and horseradish peroxidase (HRP) dually modified gold nanoparticles (AuNPs). Sens Actuators B Chem 161:1108–1113. https://doi.org/10.1016/J.SNB.2011.12.035 CrossRefGoogle Scholar