Figure 1.

The class I ligase ribozyme catalyses the same reaction chemistry as protein polymerases. The 3′-hydroxyl group of the oligonucleotide primer attacks the alpha phosphorous atom of the triphosphate at the 5′ end of the ribozyme, displacing pyrophosphate and forming a new phosphodiester linkage between the oligonucleotide primer and the ribozyme. Shown is a primary and classical secondary structure representation with helical and secondary structure elements coloured. Adapted from Koldobskaya et al. [7].