一种具有两步机制的小型金属化酶
1Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309.
Nature
|August 13, 1992
概括
离子 (Pb2+) 快速将特定的RNA分子与内部循环分裂,形成一个3'单. 这种RNA催化反应模仿了以前在RNA中未观察到的蛋白质核糖酶机制.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 在RNA催化过程中.
背景情况:
- 核糖酶 (RNases) 是催化RNA的降解的酶.
- 许多蛋白质RNase采用两步催化机制,涉及循环二中间体.
- 虽然RNA分子本身可以起到催化剂 ( ribozymes) 的作用,但它们的催化机制是多样化的,并且仍在被发现.
研究的目的:
- 为了研究具有不对称内部循环的特定RNA分子的催化活性.
- 为了阐明RNA介导裂变的反应机制.
- 为了确定RNA催化能否模仿蛋白质核糖酶机制.
主要方法:
- 在体外切割试验中,使用含有不对称内部循环的合成RNA分子进行切割试验.
- 使用凝电泳和质谱学进行裂变产品的表征.
- 在 (Pb2+) 和 (Mg2+) 离子的存在下,分裂反应的动力分析.
主要成果:
- 在Mg2+的存在下,RNA分子被Pb2+快速且特异性地分裂.
- 5' 分裂产物始终以3' 单结尾.
- 确定了一种2',3'-循环二反应中间体,这表明了两步机制.
- 这种机制反映了许多蛋白质核糖核酶的机制.
结论:
- RNA分子可以通过一种以前认为仅限于蛋白质酶的机制来催化特定的RNA裂变.
- 鉴定到的RNA分子作为一种具有新型催化机制的自我裂变 ribozyme.
- 这一发现扩大了已知的 ribozyme 功能和催化策略的范围.
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