<enzyme> An enzyme that catalyses RNA-template-directed extension of the 3'- end of an RNA strand by one nucleotide at a time, and can initiate a chain de novo. (enzyme nomenclature, 1992, p293) ... Chemical name: Nucleoside-triphosphate:RNA nucleotidyltransferase (RNA-directed) ... Registry number: EC 2.7.7.48 ... (12 Dec 1998) ...