Table 4.
DHFR and TS activities in crude extracts and purified enzymes from TS-deficient Escherichia coli χ2913 harbouring pET- pf DHFR-TS and pET- pf DHFR-TS constructs with different lengths of JR
|
Specific activity | ||||
|---|---|---|---|---|
|
Plasmid |
Crude extract* |
Purified enzyme** |
||
| |
(nmole/min/mg) |
(nmole/min/mg) |
||
| DHFR | TS | DHFR | TS | |
| 1. pET-pfDHFR-TS (3D7) |
70.3 ± 3.6 |
3.7 ± 0.4 |
5331.9 ± 113.8 |
99.0 ± 1.0 |
| 2. pET-pfDHFR-TSΔ229-265 |
64.7 ± 5.8 |
1.1 ± 0.3 |
4583.2 ± 228.9 |
44.8 ± 1.9 |
| 3. pET-pfDHFR-TSΔ229-271 |
75.5 ± 12.4 |
1.0 ± 0.3 |
3844.6 ± 130.6 |
40.9 ± 5.9 |
| 4. pET-pfDHFR-TSΔ229-274 |
74.4 ± 18.5 |
0.9 ± 0.2 |
3487.8 ± 213.2 |
35.8 ± 2.4 |
| 5. pET-pfDHFR-TSΔ229-275 |
66.7 ± 7.3 |
ND |
4719.3 ± 391.3 |
ND |
| 6. pET-pfDHFR-TSΔ229-276 |
83.9 ± 1.0 |
ND |
3357.8 ± 443.3 |
ND |
| 7. pET-pfDHFR-TSΔ229-277 |
82.1 ± 3.0 |
ND |
3137.8 ± 210.3 |
ND |
| 8. pET-15b | 3.1 ± 0.1 | ND | - | - |
* Average values from three independent experiments.
** Average values from two independent experiments.
ND: not detectable.