ReviewTwo Decades of RNA Catalysis

enzymology, the sensitive nature of RNA structure Twenty years have passed since the initial discovery brings new complexities to these experiments. Considof catalytic RNA. Although initial discoveries of riboeration of RNA catalysis in general [7, 8] and more spezymes (RNA enzymes) involved phosphoryl transfer cific discussions of ribozyme structure and function [9, reactions on RNA substrates, our knowledge of the 10] are among topics of prior reviews. Here, we focus biological repertoire of these enzymes was expanded on the current state of proposed mechanisms for four recently as a result of new evidence suggesting that ribozymes that have been the subject of particularly the RNA component of the ribosome catalyzes peptide extensive investigations. bond formation. Ribozymes have posed novel chal-