... of 23S.5 self-splicing by Mn2+is recapit-ulated by the G-dependent cleavage of 23S.5DGbpre-RNA. Mixed-metal titrations over a range of totalmetal concentrations showed that the ratio of ... absoluteconcentrations; a ratio of Mn2+⁄ Mg2+ of approxi-mately 1 : 2 or higher inhibited G-dependent cleavage of 23S.5DGbRNA (and self-splicing of 23S.5, notshown).Quantification of time-course reactions ... support catalysis by Cr.LSU. The data doindicate, however, that Mn2+inhibits formation of theactive ribozyme, presumably by causing misfolding.This result was unexpected, because of the extensivework...