Purification,Properties, and Application of a Novel Acid Urease from <Emphasis Type="Italic">Enterobacter</Emphasis> sp. |
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Authors: | Lu-qiang Yang Song-hua Wang Ya-ping Tian |
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Institution: | (1) The Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China; |
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Abstract: | It has been demonstrated that acid urease is capable of decomposing urea in fermented beverage and foods. As urea is a precursor
of ethylcarbamate, a potential carcinogenic compound, measures must be taken to control the level of urea. We herein describe
the purification and characterization of a novel acid urease from Enterobacter sp. R-SYB082 and its application to the removal of urea in Chinese rice wine. The enzyme was purified to electrophoretic
homogeneity using ethanol precipitation, Superdex 200 and Mono Q with a fold purification of 21.1 and a recovery of 49%. The
molecular weight of the enzyme was 430,000 Da by gel filtration and 72,000 Da by sodium dodecyl sulfate polyacrylamide gel
electrophoresis, suggesting that it was a hexamer. The activity of this purified enzyme was optimal at pH 4.5 and 35 °C. The
temperature stability was under 55 °C, and the pH stability was 4.0~5.0. The enzyme exhibited an apparent K
m of 19.5 μmol/l and a V
max of 109 μmol urea/mg·min at 35 °C and pH 4.5. When incubating two different kinds of Chinese rice wine with the enzyme (0.08 U/ml)
at 35 °C for 7 days, over 85% of urea was decomposed, and at 20 °C, above 78% was removed. The result showed that the enzyme
is applicable to elimination of urea in Chinese rice wine. |
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