... Contribu-tions of 2¢-hydroxyl groups of the RNA substrate tobinding and catalysis by the Tetrahymena ribozyme. Anenergetic picture of an active site composed of RNA.Biochemistry 32, 8299–8311.23 ... introns catalyze the self-splicing reaction, and their derived ribo-zymes are frequently used as model systems for the study of RNA foldingand catalysis, as well as for the development of non-native ... seen with other ribozymes [6,8,13,18,19,43]. Thus, the rate of assembly of the Pneumocystis ribozyme–substrate complex appears to be limited by the process of helix formation. Nevertheless, because...