Table 1.

Rates of cleavage by hammerhead and pistol ribozymes

Ribozyme	MgCl2 + NaCl		NaCl only
	Rate/min−1	Fold	Rate / min−1	fold
PK hammerhead dG8	16 ± 1 0.66 ± 0.02	(1) 25	3.5 ± 0.3 0.0011 ± 0.0004	4.6 14,000
Extend. hammerhead dG8	0.72 ± 0.03 0.0042 ± 0.0001	(1) 171	0.21 ± 0.002 (6.4 ± 0.2) x 10−5	3.4 11,000
Pistol dA32	9.77 ± 0.6 0.15 ± 0.1	(1) 66	0.0184 ± 0.00003 0.0005 ± 0.00002	530 20,000

The rates for the PK hammerhead ribozyme were measured in the present work. Most of the data for the extended hammerhead and pistol ribozyme were taken from our earlier study²³ except for those for the pistol ribozyme in the absence of Mg²⁺ that were measured in the present work. Note that all the measurements were made in a background concentration of 2 M NaCl. Fold reductions in rate are relative to ribozyme with a 2’-hydroxyl group at position 8 (hammerhead) or 32 (pistol), in the presence of 1 mM MgCl₂ and 2 M NaCl. Cleavage rates for the PK hammerhead ribozyme were determined in triplicate, and the mean and standard deviation reported.