TABLE 2.

Kinetic parameters generated for wild type and mutant muCOX-2 constructs using AA

k_cat and K_m values were derived from three independent determinations (±S.E.) using 24–72 nm protein and an oxygen electrode. Efficiency (E) is defined as the k_cat/K_m. Values for the relative peroxidase activity represent the average of two measurements followed by normalization to the rate of wild type enzyme. ND, not determined.

Construct	AA (20:4 ω-6)			Relative peroxidase activity
	kcat	Km	E
	s−1	μm
Wild type	26.7 ± 0.5	8.4 ± 0.7	3.2	100
R120A	28.4 ± 0.4a	28.7 ± 1.1a	1.0	104
R120A/G533A	ND	ND	ND	104
F205A	7.8 ± 0.1a	10.7 ± 0.7	0.7	42
F205V	13.5 ± 0.4a	11.1 ± 1.0a	1.2	89
F205L	18.9 ± 0.4a	15.5 ± 0.9a	1.2	137
F209A	9.8 ± 0.2a	13.3 ± 0.8a	0.7	88
F209V	26.2 ± 0.5	12.6 ± 0.6a	2.1	145
F209L	34.4 ± 0.7a	11.3 ± 0.7	3.0	207
I377V	23.1 ± 0.5a	10.3 ± 0.7	2.2	92
I377L	19.2 ± 0.3a	5.0 ± 0.3a	3.8	72
G533A	ND	ND	ND	104
G533V	ND	ND	ND	93

^a Values differ from the wild type construct value as determined using an unpaired Student's t test (p < 0.02).