. Author manuscript; available in PMC: 2008 Aug 17.

Published in final edited form as: Biochemistry. 2006 Jun 20;45(24):7463–7473. doi: 10.1021/bi0602314

Table 4.

The kinetic relationship between N265 and P267 for tRNA methylation

	k_cat (min^-1)	K_m(μM)	k_cat/K_m (μM^-1min^-1)	Relative k_cat/K_m
Wild-type Trm5	0.5 ± 0.08	0.7 ± 0.03	0.7 ± 0.05	1.0
N265H	0.2 ± 0.01	0.8 ± 0.04	0.25 ± 0.02	0.33
N265Q	0.03 ± 0.01	3.2 ± 1.0	0.011 ± 0.006	0.01
P267A Trm5	0.006 ± 0.001	6.0 ± 0.9	0.001 ± 0.001	0.001
N265H/P267A	0.006 ± 0	5.1 ± 0.1	0.001 ± 0.001	0.001
N265Q/P267A	0.007 ± 0.001	4.2 ± 0.4	0.001 ± 0.0005	0.001

The N265H and N265Q mutants were assayed by 100 and 600 nM Trm 5 with 0.5-12 and 2.5-15 μM of tRNA, respectively. The N265H/P267A and N265Q/P267A mutants were assayed by 750 nM Trm 5 with 2.5-15 tRNA. Aliquots of assay reactions were analyzed at 5, 10, 15, and 25 min.