In Vitro Selected (Deoxy)ribozymes that Catalyze Carbon–Carbon Bond Formation

In vitro selection of randomized RNA libraries for ribozymes that catalyze different chemical transformations is a method that has been established in the mid-1990ies. Until now, the method has led to many RNAs that catalyze a wide variety of reactions, several of which are highly relevant for supporting the RNA world hypothesis. According to this hypothesis, there was a phase in the evolution of the earliest life forms on earth around 3.9 billion years ago in which protein enzymes had not been established the way they are now. Instead, prebiotic catalysis was likely carried out by ribozymes. In this chapter, I discuss examples of ribozymes with particular emphasis on the catalysis of C-C-bond formations and their hypothetical role for RNA-catalyzed metabolism in an RNA world.