Beaudry A A, Joyce G F
Department of Chemistry, Scripps Research Institute, La Jolla, CA 92037.
Science. 1992 Jul 31;257(5070):635-41. doi: 10.1126/science.1496376.
An in vitro evolution procedure was used to obtain RNA enzymes with a particular catalytic function. A population of 10(13) variants of the Tetrahymena ribozyme, a group I ribozyme that catalyzes sequence-specific cleavage of RNA via a phosphoester transfer mechanism, was generated. This enzyme has a limited ability to cleave DNA under conditions of high temperature or high MgCl2 concentration, or both. A selection constraint was imposed on the population of ribozyme variants such that only those individuals that carried out DNA cleavage under physiologic conditions were amplified to produce "progeny" ribozymes. Mutations were introduced during amplification to maintain heterogeneity in the population. This process was repeated for ten successive generations, resulting in enhanced (100 times) DNA cleavage activity.
采用体外进化程序来获得具有特定催化功能的RNA酶。生成了一群含有10¹³个四膜虫核酶变体的群体，四膜虫核酶是一种I型核酶，通过磷酸酯转移机制催化RNA的序列特异性切割。在高温或高MgCl₂浓度或两者兼具的条件下，这种酶切割DNA的能力有限。对核酶变体群体施加了选择限制，使得只有那些在生理条件下进行DNA切割的个体被扩增以产生“子代”核酶。在扩增过程中引入突变以维持群体的异质性。这个过程连续重复十代，导致DNA切割活性增强（100倍）。
