Abstract
Watermelon (Citrullus vulgaris) urease was immobilized in 3.5% alginate leading to 72% immobilization. There was no leaching of the enzyme over a period of 15 days at 4°C. It continued to hydrolyse urea at a faster rate upto 90 min of incubation. The immobilized urease exhibited a shift of apparent pH optimum by one unit towards acidic side (from pH 8.0 to 7.0). The Km was found to be 13.3 mM; 1.17 times higher than the soluble enzyme (11.4 mM). The beads were fairly stable upto 50°C and exhibited activity even at −10°C. The enzyme was significantly activated by ME and it exhibited two peaks of activation; one at lower concentration and another at higher concentration. Time-dependent ureolysis in presence of ME progressed at a much elevated rate. Unlike soluble enzyme, which was inhibited at 200 mM urea, the immobilized enzyme was inhibited at 600 mM of urea and above, and about 47% activity was retained at 2000 mM urea. Moreover, the inhibition caused by high urea concentration was partially abolished by ME. The significance of the observations is discussed.
Abbreviations
- ME:
-
β-mercaptoethanol
- DTT:
-
dithiothreitol
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Prakash, O., Upadhyay, L.S.B. Physico-Chemical Characterization of Watermelon Urease upon Immobilization in Alginate Beads. J. Plant Biochem. Biotechnol. 14, 209–213 (2005). https://doi.org/10.1007/BF03263249
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DOI: https://doi.org/10.1007/BF03263249