TABLE 2. Dissociation constants for AUCG and AUCI in the WT and A261H ribozymes (see Scheme 2).

Ribozyme	Nucleophile	${(K_{\text{d}}^{\text{AUCX}})}_{\text{o}}$		${(K_{\text{d}}^{\text{AUCX}})}_{\text{c}}$
		(μM)	Relative	(μM)	Relative
WT	AUCG	7.0	(1.0)	2.7	(1.0)
	AUCI	380	54	360	130
A261H	AUCG	5.0	0.71	29	11
	AUCI	180	26	390	140