Effect of terminal 3'-hydroxymethyl modification of an RNA primer on nonenzymatic primer extension.

The significance of the precise position of the hydroxyl at the 3'-end of an RNA primer for nonenzymatic template-directed primer extension is not well understood. We show that an RNA primer terminating in 3'-hydroxymethyl-2',3'-dideoxy-guanosine has greatly diminished activity, suggesting that the spatial preorganization of the terminal sugar contributes significantly to the efficiency of primer extension.