Urea degradation in model wine solutions by free or immobilized acid urease in a stirred bioreactor.
Urea degradation in model wine solutions by free or immobilized acid urease in a stirred bioreactor.
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DOI：
10.1021/jf803962b
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发表时间：
2009-05
影响因子：
6.1
通讯作者：
Lucia Andrich;M. Esti;M. Moresi
中科院分区：
文献类型：
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作者：
Lucia Andrich;M. Esti;M. Moresi
在本工作中，纯化的酸性尿素酶制剂被共价固定在EupergitC250 L上，并用甘氨酸稳定。在4℃下保存34天后，其平均活性为初始活性的69+/-16%。在模拟葡萄酒溶液中，固定化酶降解尿素的动力学与溶液中尿素浓度呈准一级反应，其表观准一级动力学速率常数(k(II))约为游离酶反应速率常数(k(IF))的四分之一。在所测试的操作条件下，反应动力学估计为不受外膜和颗粒内扩散传质阻力的影响。由于从葡萄籽中提取的高抑制单宁在3-620g GAEm(-3)的范围内，k(II)的损失比k(IF)的损失要小得多，所以本文所测试的生物催化剂有可能克服目前游离酸性尿素酶在葡萄酒处理中应用的局限性。
In this work, a purified acid urease preparation was covalently immobilized on Eupergit C 250 L and stabilized with glycine. Its average activity was found to be 69 +/- 16% of the initial one after 34-day storage at 4 degrees C . The kinetics of urea degradation in a model wine solution by immobilized enzyme was confirmed to be of pseudo-first-order with respect to the urea concentration in the liquid bulk, its apparent pseudo-first-order kinetic rate constant (k(Ii)) being about one-fourth of that (k(If)) pertaining to the free enzyme. In the operating conditions tested, the reaction kinetics was estimated as unaffected by the contribution of the external film and intraparticle diffusion mass transfer resistances. Because in the presence of the high-inhibitory tannins extracted from grape seeds in the range of 3-620 g of GAE m(-3) the loss in k(Ii) was quite smaller than that in k(If), the biocatalyst tested here is likely to overcome the present limits to the application of free acid urease in wine treatment.