Multiple turnover kinetic analysis of RNA oligonucleotide substrate cleavage by the D1356 ribozyme. The ribozyme was either preincubated to full compaction at 30 °C and 3, 5, 10 or 20 mM MgCl2 ((a), (b)) or prefolded to a native state at 100 mM MgCl2 and 42 °C and then diluted to the same magnesium concentrations as above ((c), (d)). All reactions were carried out at 30 °C and either 3, 5, 10 or 20 mM MgCl2, respectively, ((a), (c)) or at 100 mM MgCl2 ((b), (d)). Unfolded and native ribozyme samples were used as controls for comparison of rate constants ((b), (d)).