A novel strategy of chemical modification for rate enhancement of 10–23 DNAzyme: a combination of A9 position and 8-aza-7-deaza-2′-deoxyadenosine analogs
作者:Junlin He、Di Zhang、Qi Wang、Xia Wei、Maosheng Cheng、Keliang Liu
DOI:10.1039/c1ob05065f
日期:——
With the help of a divalent-metal ion, 10â23 DNAzyme cleaves RNA. Chemical modification of its catalytic loop to make a more efficient enzyme has been a challenge. Our strategy started from its five 2â²-deoxyadenosine residues (A5, A9, A11, A12, and A15) in the loop based on the capability of the N7 atom to form hydrogen bonds in tertiary structures. 8-Aza-7-deaza-2â²-deoxyadenosine and its analogs with 7-substituents (3-aminopropyl, 3-hydroxylpropyl, or phenethyl) were each used to replace five dA residues, respectively, and their effect on cleavage rate were evaluated under single-turnover conditions. The results indicated that the N7 atom of five dA residues were necessary for catalytic activity, and the N8 atom and 7-substituents were detrimental to the catalytic behavior of 10â23 DNAzyme, except that all these modifications at A9 were favourable for the activity. Especially, DZ-3â9 with 7-(3-aminopropyl)-8-aza-7-deaza-2â²-deoxyadenosine (3) at A9 position gave a 12- fold increase of kobs, compared to the corresponding parent 10â23 DNAzyme. DZ-3â9 was supposed to catalyze the cleavage reaction with the same mechanism as 10â23 DNAzyme based on their very similar pH-dependent and divalent metal ions-dependent cleavage patterns. Introduction of functional groups at A9 position was demonstrated to be a successful and feasible approach for more efficient 10â23 DNAzyme analogs.
在二价金属离子的帮助下,10-23 DNAzyme 切割 RNA。对其催化环进行化学修饰以制造更有效的酶一直是一个挑战。我们的策略从环中的五个 2-脱氧腺苷残基(A5、A9、A11、A12 和 A15)开始,基于 N7 原子在三级结构中形成氢键的能力。 8-Aza-7-deaza-2α-脱氧腺苷及其带有7个取代基的类似物(3-氨丙基、3-羟丙基或苯乙基)分别用来取代5个dA残基,它们对裂解率的影响为在单周转条件下进行评估。结果表明,5个dA残基的N7原子是催化活性所必需的,N8原子和7位取代基不利于10-23 DNAzyme的催化行为,但A9处的所有这些修饰都有利于活性。 。特别是,与相应的亲本相比,在 A9 位置具有 7-(3-氨基丙基)-8-aza-7-deaza-2â2-脱氧腺苷 (3) 的 DZ-3â9 的 kobs 增加了 12 倍10-23 DNA酶。 DZ-3-9 被认为以与 10-23 DNAzyme 相同的机制催化裂解反应,基于它们非常相似的 pH 依赖性和二价金属离子依赖性裂解模式。在 A9 位置引入功能基团被证明是一种成功且可行的方法,可实现更有效的 10-23 DNAzyme 类似物。