. 2010 Aug 12;38(22):8316–8327. doi: 10.1093/nar/gkq668

Table 1.

Effect of Mth RPPs on the ionic requirements and rate of cleavage of pre-tRNA^Tyr by Mth RPR at 55°C^a

Assayed under the optimal condition for each catalytic entity						Assayed under the optimal condition for the holoenzyme with four RPPs (30 mM Mg²⁺, 800 mM NH₄⁺
	Max. k_obs^a, min⁻¹	K_M(STO)^a, µM	[NH₄⁺], M	[Mg²⁺], M	Relative		k_obs, min⁻¹	Relative
	Max. k_obs^a, min⁻¹	K_M(STO)^a, µM	[NH₄⁺], M	[Mg²⁺], M	max. k_obs		k_obs, min⁻¹	k_obs
Mth RPR	0.13 ± 0.01	21.3 ± 2.6	2.0	0.50	1	Mth RPR (3 µM)	^b	–
Mth RPR + RPP21•RPP29	0.13 ± 0.01	1.4 ± 0.2	0.8	0.12	1	Mth RPR + RPP21•RPP29	^b	–
Mth RPR + POP5•RPP30	7.9 ± 1	11.8 ± 2.3	0.8	0.12	∼60	Mth RPR + POP5•RPP30	0.016 ± 0.0004	1
Mth RPR + Both binary RPP complexes	7.5 ± 0.14^c	1.2 ± 0.1	0.8	0.03	∼60	Mth RPR + Both binary RPP complexes	5.5 ± 0.18^c	∼344

^aThe standard errors of the curve fits shown in Figure 7 are indicated in the estimates of max. k_obs and K_M(STO).

^bReliable data could not be obtained due to weak or negligible activity.

^cAll experiments were performed at pH 5.8, except for Mth RPR reconstituted with both binary RPP complexes, which was assayed at pH 5.4. After establishing a slope of approximately 1 in a plot of log k_obs versus pH (see Supplementary Figure S6), we multiplied the maximal rate observed at pH 5.4 by 2.5 to obtain the rate that would have been observed at pH 5.8 should it have been measurable.