Department of Chemistry and Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, United States.
Laboratory for Biomolecular Simulation Research, Institute for Quantitative Biomedicine, Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, United States.
J Am Chem Soc. 2023 Feb 8;145(5):2830-2839. doi: 10.1021/jacs.2c10079. Epub 2023 Jan 27.
Ribonucleases and small nucleolytic ribozymes are both able to catalyze RNA strand cleavage through 2'--transphosphorylation, provoking the question of whether protein and RNA enzymes facilitate mechanisms that pass through the same or distinct transition states. Here, we report the primary and secondary O kinetic isotope effects for hepatitis delta virus ribozyme catalysis that reveal a dissociative, metaphosphate-like transition state in stark contrast to the late, associative transition states observed for reactions catalyzed by specific base, Zn ions, or ribonuclease A. This new information provides evidence for a discrete ribozyme active site design that modulates the RNA cleavage pathway to pass through an altered transition state.
核糖核酸酶和小核酶都能够通过 2'--磷酸转移催化 RNA 链断裂，这引发了一个问题，即蛋白质酶和 RNA 酶是否促进了相同或不同的过渡态机制。在这里，我们报告了乙型肝炎 delta 病毒核酶催化的主、次氧动力学同位素效应，这表明了一种离散的核酶活性位点设计，该设计调节 RNA 切割途径以通过改变的过渡态。
