Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824-4320, USA.
Metallomics. 2009;1(3):207-21. doi: 10.1039/b903311d.
Urease, the first enzyme to be crystallized, contains a dinuclear nickel metallocenter that catalyzes the decomposition of urea to produce ammonia, a reaction of great agricultural and medical importance. Several mechanisms of urease catalysis have been proposed on the basis of enzyme crystal structures, model complexes, and computational efforts, but the precise steps in catalysis and the requirement of nickel versus other metals remain unclear. Purified bacterial urease is partially activated via incubation with carbon dioxide plus nickel ions; however, in vitro activation also has been achieved with manganese and cobalt. In vivo activation of most ureases requires accessory proteins that function as nickel metallochaperones and GTP-dependent molecular chaperones or play other roles in the maturation process. In addition, some microorganisms control their levels of urease by metal ion-dependent regulatory mechanisms.
脲酶是最早被结晶的酶之一，它含有一个双核镍金属中心，可催化尿素分解为氨，这是一个具有重要农业和医学意义的反应。基于酶晶体结构、模型配合物和计算研究，提出了几种脲酶催化机制，但催化的确切步骤以及镍与其他金属的需求仍不清楚。纯化的细菌脲酶通过与二氧化碳和镍离子孵育而部分激活；然而，体外激活也可以用锰和钴来实现。大多数脲酶的体内激活需要辅助蛋白，这些蛋白作为镍金属伴侣蛋白和 GTP 依赖性分子伴侣发挥作用，或者在成熟过程中发挥其他作用。此外，一些微生物通过依赖于金属离子的调节机制来控制其脲酶的水平。
