Urease reaction rates at low water activity |
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Authors: | J Skuji?? A D McLaren |
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Institution: | (1) Department of Soils and Plant Nutrition, University of California, Berkeley, Calif., USA;(2) Present address: Department of Bacteriology and Public Health, Utah State University, 84321 Logan, Utah |
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Abstract: | Hydrolysis of urea by urease takes place in dry urea-urease mixture exposed to discrete water vapor pressures from 100% to 20% relative humidity and at 2°C to 70°C. A discontinuity in enzymatic activities is observed at the transition of urea from a solid to a deliquescent solution. Urease is inactivated more readily at higher relative humidities in saturated urea solution than at lower relative humidities where water for urea hydrolysis is adsorbed on enzyme-protein only. Hydrolysis of urea by urease proceeds at a measurable rate in concentrated solutions of urea and of urea hydrolysis products, ammonium carbonate and bicarbonate, in the absence of ionic strength or pH stabilizing agents. |
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