Table 2.
TXAS kinetic parameters for purified wild-type and variant proteinsa.
| wild-type | K258E | L357V | Q417E | E450K | T451N | |
|---|---|---|---|---|---|---|
| KM, µM PGH2 | 32.0 ± 2.7 | 51.9 ± 4.3 (p= 0.017)b |
51.0 ± 2.5 (p= 0.007) |
27.1 ± 3.6 (p> 0.05) |
33.8 ± 2.4 (p> 0.05) |
46.7 ± 3.9 (p= 0.036) |
| Vmax, units /mg protein |
40.8 ± 1.0 | 32.9 ± 1.0 (p= 0.005) |
18.1 ± 1.0 (p= 0.0001) |
39.7 ± 1.0 (p> 0.05) |
32.9 ± 1.0 (p= 0.005) |
34.0 ± 1.0 (p= 0.009) |
| Vmax /KM, units/mg/µM PGH2 |
1.28 ± 0.14 | 0.64 ± 0.07 (p= 0.015) |
0.35 ± 0.04 (p=0.0031) |
1.46 ± 0.23 (p> 0.05) |
0.97 ± 0.10 (p> 0.05) |
0.72 ± 0.08 (p= 0.025) |
a
Activity was assayed by following the absorbance changes at 268 nm for MDA formation in the presence of 5 nM TXAS. Values represent mean ± SEM of three experiments.
b
p-values are calculated as compared to the wild-type, and values larger than 0.05 are considered to be statistically in-significant.