Dai X, De Mesmaeker A, Joyce G F
Department of Chemistry, Scripps Research Institute, La Jolla, CA 92037.
Science. 1995 Jan 13;267(5195):237-40. doi: 10.1126/science.7809628.
A variant form of a group I ribozyme, optimized by in vitro evolution for its ability to catalyze magnesium-dependent phosphoester transfer reactions involving DNA substrates, also catalyzes the cleavage of an unactivated alkyl amide when that linkage is presented in the context of an oligodeoxynucleotide analog. Substrates containing an amide bond that joins either two DNA oligos, or a DNA oligo and a short peptide, are cleaved in a magnesium-dependent fashion to generate the expected products. The first-order rate constant, kcat, is 0.1 x 10(-5) min-1 to 1 x 10(-5) min-1 for the DNA-flanked substrates, which corresponds to a rate acceleration of more than 10(3) as compared with the uncatalyzed reaction.
I组核酶的一种变体形式,通过体外进化对其催化涉及DNA底物的镁依赖性磷酸酯转移反应的能力进行了优化,当未活化的烷基酰胺键出现在寡脱氧核苷酸类似物的背景中时,它也能催化该键的裂解。含有连接两个DNA寡核苷酸或一个DNA寡核苷酸和一个短肽的酰胺键的底物以镁依赖性方式裂解,生成预期产物。对于DNA侧翼的底物,一级速率常数kcat为0.1×10^(-5) min^(-1)至1×10^(-5) min^(-1),与未催化反应相比,这相当于速率加速超过10^3。