An RNA has been selected that rapidly aminoacylates its 2'(3') terminu
s when provided with phenylalanyl-adenosine monophosphate. That is, th
e RNA accelerates the same aminoacyl group transfer catalyzed by prote
in aminoacyl-transfer RNA synthetases. The best characterized RNA reac
tion requires both Mg2+ and Ca2+. These results confirm a necessary pr
ediction of the RNA world hypothesis and represent efficient RNA react
ion (greater than or equal to 10(5) times accelerated) at a carbonyl c
arbon, exemplifying a little explored type of RNA catalysis.