A series of 10â23 deoxyribozymes (D2âD9) containing single amino-acid-bearing nucleosides (thr6dA, hisam6dA, hisam5dU and ncmnm5dU) at positions 4, 5, 8 or 15 of the catalytic core was obtained by chemical synthesis. The deoxyribozymes were screened for their catalytic efficiency, and in the presence of 1 mM Mg2+ two of them, containing at position 8 either hisam5dU (D8) or ncmnm5dU (D9), were found to be RNA nucleases several times more active than their non-modified precursor. Moreover, in the magnesium-free TRIS or PIPES buffers, these enzymes were able to catalyze the cleavage of the phosphodiester bond located between the 5â²-GpU-3â² sequence of the complementary RNA substrate. The cleavage reaction proceeded with the highest efficiency at pH > 7.
通过
化学合成获得了一系列 10â23 个
脱氧核糖核酸酶(D2âD9),它们在催化核心的第 4、5、8 或 15 位含有单个
氨基酸核苷(thr6dA、hisam6dA、hisam5dU 和 ncmnm5dU)。对这些脱氧
核糖酶的催化效率进行了筛选,发现在 1 mM Mg2+ 的存在下,其中两种在第 8 位含有 hisam5dU(D8)或 ncmnm5dU(D9)的 RNA 核酶的活性是其未修饰前体的数倍。此外,在无
镁的 TRIS 或
PIPES 缓冲液中,这些酶能够催化位于互补 RNA 底物的 5â²-GpU-3â² 序列之间的
磷酸二酯键的裂解。当 pH 值大于 7 时,裂解反应的效率最高。