. Author manuscript; available in PMC: 2008 Feb 23.

Published in final edited form as: J Mol Biol. 2006 Dec 2;366(3):882–899. doi: 10.1016/j.jmb.2006.11.065

Table 3.

Steady-state kinetic parameters of trypanosomal TbTUT4 mutants with UTP.

Protein	K_m (μM)	±	k_cat (min⁻¹)	±	k_cat/K_m (min⁻¹ M⁻¹)	[k_cat/K_m]_mutant/ [k_cat/K_m]_w.t.
TUT4	1	0.9	0.5	0.06	5 × 10⁵	1.0
TUT4/dUTP	12.2	5.4	0.2	0.02	1.6 ×10³	0.003
F52A	Inactive		Inactive		Inactive	Inactive
D66A	Inactive		Inactive		Inactive	Inactive
D68A	Inactive		Inactive		Inactive	Inactive
R121A	2.8	5.1	0.002	0.0006	8.6 × 10²	0.002
R121F	Inactive		Inactive		Inactive	Inactive
R126A	Inactive		Inactive		Inactive	Inactive
D136A	Inactive		Inactive		Inactive	Inactive
R141A	1.0	2.1	0.007	0.0005	6.3× 10³	0.01
N147A	115.3	10.5	0.3	0.02	2.6 × 10³	0.0005
S148A	87.3	49.2	1.3	0.5	1.4 × 10⁴	0.03
S188A	34.0	11.4	0.03	0.007	8.8 × 10²	0.002
Y189A	Inactive		Inactive		Inactive	Inactive
Y189F	21.3	3.6	0.9	0.04	4.2 × 10⁴	0.09
D297A	172.8	265.5	0.02	0.003	9.1 × 10¹	0.0002
D297N	13.9	25.7	0.004	0.001	2.9 × 10²	0.0006
E300A	308.4	161.5	0.4	0.1	1.3 × 10³	0.003
R307A	0.4	1.2	0.008	0.0004	2.0 × 10⁴	0.04