Abstract The pseudoknot-type hammerhead ribozyme (PK-HHRz) is known to be activated by a pseudoknot interaction between loops I and II. To obtain maximal activation through the pseudoknot formation, we studied the structure–activity relationship of PK-HHRz. From these studies, the structural requirements of the PK-HHRz cleavage reaction were clearly defined. In addition, we discovered a PK-HHRz with higher cleavage activity than the wild-type sequence. Although modifications generally disrupt the activity of enzymes, in this case the elongation of loop II increased the activity of PK-HHRz. These new findings will form a structural basis for designing PK-HHRz variants for gene-therapeutic/manipulating agents and biochemical/nanotechnological tools.

中文翻译：

---

假结型锤头状核酶的构效关系揭示了增强催化活性的关键结构要素†

摘要 已知假结型锤头状核酶 (PK-HHRz) 被环 I 和环 II 之间的假结相互作用激活。为了通过假结的形成获得最大的活化，我们研究了 PK-HHRz 的构效关系。从这些研究中，明确定义了 PK-HHRz 裂解反应的结构要求。此外，我们发现了比野生型序列具有更高切割活性的 PK-HHRz。尽管修饰通常会破坏酶的活性，但在这种情况下，环 II 的延伸增加了 PK-HHRz 的活性。这些新发现将为设计用于基因治疗/操纵剂和生化/纳米技术工具的 PK-HHRz 变体奠定结构基础。