Nakamatsu Y, Warashina M, Kuwabara T, Tanaka Y, Shibata A, Yoshinari K, Taira K
National Institute for Advanced Interdisciplinary Research, AIST, MITI, Tsukuba Science City, Japan.
Nucleic Acids Symp Ser. 1999(42):283-4. doi: 10.1093/nass/42.1.283.
Recently, hammerhead ribozyme-mediated cleavage was analyzed as a function of the concentration of La3+ ions in the presence of a fixed concentration of Mg2+ ions so that the role could be monitored of metal ions that are directly involved in the cleavage reaction. The resultant bell-shaped curve for activation of cleavage was used to support the proposed double-metal-ion mechanism of catalysis. However, other studies demonstrated that binding of a metal ion to the pro-Rp oxygen (P9 oxygen) of the phosphate moiety of nucleotide A9 and N7 of nucleotide G10.1 is critical for efficient catalysis. In order to clarify the effect of this metal ion, we chemically synthesized hammerhead ribozyme (7-deaza-R34) that included a minimal modification, namely, an N7-deazaguanine residue in place of G10.1.
最近，在固定浓度的Mg2+离子存在的情况下，分析了锤头状核酶介导的切割作用与La3+离子浓度的函数关系，以便监测直接参与切割反应的金属离子的作用。所得的切割活化钟形曲线被用来支持所提出的双金属离子催化机制。然而，其他研究表明，金属离子与核苷酸A9的磷酸基团的前-Rp氧（P9氧）和核苷酸G10.1的N7结合对于高效催化至关重要。为了阐明这种金属离子的作用，我们化学合成了锤头状核酶（7-脱氮-R34），其包含一个最小修饰，即一个N7-脱氮鸟嘌呤残基取代G10.1。
