Kinetics of the urea-urease clock reaction with urease immobilized in hydrogel beads
Kinetics of the urea-urease clock reaction with urease immobilized in hydrogel beads
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DOI：
10.1007/s11144-017-1296-6
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发表时间：
2018-02-01
影响因子：
1.8
通讯作者：
Taylor, Annette Fiona
中科院分区：
文献类型：
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作者：
Bubanja, Itana Nusa;Bansagi, Tamas, Jr.;Taylor, Annette Fiona
由酶催化反应驱动的反馈在生物学中广泛存在，并且已经在单细胞生物如酵母中得到很好的表征。仍然有一些例子，强大的酶振荡器在体外，可用于研究非线性动力学行为。其中最简单的是尿素-尿素酶反应，其显示由伴随氨产生的pH增加驱动的自催化作用。在间歇反应器中，从低pH到高pH得到时钟反应，在连续流动反应器中报道了双稳态和振荡。然而，发现振荡是不可再现的，一个促成因素可能是在室温下酶在溶液中缺乏稳定性。在这里，我们研究了固定化尿素酶在硫醇-聚（乙二醇）丙烯酸酯（PEGDA）水凝胶珠，采用乳液聚合制备的尿素-尿素酶反应的效果。发现所得的mm大小的珠粒再现pH时钟，并且在本文所用的条件下，酶的稳定性从数小时增加到数天。
Feedback driven by enzyme catalyzed reactions occurs widely in biology and has been well characterized in single celled organisms such as yeast. There are still few examples of robust enzyme oscillators in vitro that might be used to study nonlinear dynamical behavior. One of the simplest is the urea-urease reaction that displays autocatalysis driven by the increase in pH accompanying the production of ammonia. A clock reaction was obtained from low to high pH in batch reactor and bistability and oscillations were reported in a continuous flow rector. However, the oscillations were found to be irreproducible and one contributing factor may be the lack of stability of the enzyme in solution at room temperature. Here, we investigated the effect of immobilizing urease in thiol-poly(ethylene glycol) acrylate (PEGDA) hydrogel beads, prepared using emulsion polymerization, on the urea-urease reaction. The resultant mm-sized beads were found to reproduce the pH clock and, under the conditions employed here, the stability of the enzyme was increased from hours to days.