Perreault J P, Labuda D, Usman N, Yang J H, Cedergren R
Département de biochimie and de pédiatrie, Université de Montréal, Québec, Canada.
Biochemistry. 1991 Apr 23;30(16):4020-5. doi: 10.1021/bi00230a029.
The use of deoxyribonucleotide substitution in RNA (mixed RNA/DNA polymers) permits an evaluation of the role of 2'-hydroxyl groups in ribozyme catalysis. Specific deoxyribonucleotide substitution at G9 and A13 of the ribozyme decreases the catalytic activity (kcat) of the ribozyme by factors of 14 and 20, respectively. The reduction of the reaction rate concomitant with the absence of these 2'-OHs or the 2'-OH of the substrate U7 position can be partially compensated by increasing the Mg2+ concentration above 10 mM. The KMg of the all-RNA ribozyme is 5.3 mM, and the lack of either of the three influential 2'-OHs increases this value by a factor of approximately 3. These and other reaction constants for the ribozyme and the deoxy-substituted analogues have been determined by assuming a three-step mechanism. The data presented here provide the basis for the formulation of a molecular model of ribozyme activity.
在RNA（混合RNA/DNA聚合物）中使用脱氧核糖核苷酸取代，能够评估2'-羟基在核酶催化中的作用。在核酶的G9和A13位点进行特定的脱氧核糖核苷酸取代，会使核酶的催化活性（kcat）分别降低14倍和20倍。当这些2'-OH或底物U7位置的2'-OH缺失时，反应速率降低，通过将Mg2+浓度提高到10 mM以上可部分补偿这一降低。全RNA核酶的KMg为5.3 mM，三个有影响的2'-OH中任一个缺失都会使该值增加约3倍。通过假设三步机制确定了核酶及脱氧取代类似物的这些和其他反应常数。此处给出的数据为构建核酶活性分子模型提供了基础。
