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大肠杆菌I型异二酸异酶:双价金属的结构和催化作用

Sungwon Lee¹, C Dale Poulter

¹Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, USA.

Journal of the American Chemical Society

|August 31, 2006

概括

异二酸异相酶 (IDI) 需要两个金属离子进行活性. 2+) 有助于二酸盐结合,而2+) 或2+) 在六坐标位点结合,这对于异烯酸生物合成至关重要.

科学领域:

生物化学生物化学
酶学是一种酶学.
代谢途径代谢途径

背景情况:

异二酸盐异酶 (IDI) 对于美酸盐路径至关重要,催化异二酸盐 (IPP) 和二甲基亚酸盐 (DMAPP) 的相互转化.
在真核生物和细菌中发现的I型IDI,利用质子化-脱质子化机制,需要两个双价金属离子进行催化.
之前使用过渡状态类型的结构研究表明了特定的金属离子结合点.

研究的目的:

研究不同双价金属离子在I型IDI活动中的作用.
为了确定净化复合大肠杆菌IDI的金属离子组成.
为了将金属离子结合与酶结构和功能相关联.

主要方法:

用各种双价金属 (Mg(2+),Mn(2+),Zn(2+),Co(2+),Ni(2+),Cd(2+) 来复制无金属的复合大肠杆菌IDI.
在金属复制后进行酶活性测定.
感应合等离子体质谱法 (ICP-MS) 或原子吸收光谱法用于量化纯化酶制剂中的金属含量.

主要成果:

用多种双价金属溶解生成了活性IDI酶.
新净化的IDI含有单个金属离子的亚体化学水平,可能在六坐标位点.
在 (N,N-dimethylamino) -1-乙基二酸盐 (NIPP) 的存在下净化的酶显示出显著的Mg2+和Zn2+含量,含量较少的Mn2+).

结论:

2+) 可能在I型IDI中促进二酸盐结合.
建议Zn(2+) 或Mn(2+) 占据六坐标金属结合点.
这些发现阐明了IDI活动的金属离子要求,并提供了对催化机制的结构洞察.

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