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-pf DHFR-TS (3D7) | 70.3 ± 3.6 | 3.7 ± 0.4 | 5331.9 ± 113.8 | 99.0 ± 1.0 |
2. pET-pf DHFR-TSΔ229-265 | 64.7 ± 5.8 | 1.1 ± 0.3 | 4583.2 ± 228.9 | 44.8 ± 1.9 |
3. pET-pf DHFR-TSΔ229-271 | 75.5 ± 12.4 | 1.0 ± 0.3 | 3844.6 ± 130.6 | 40.9 ± 5.9 |
4. pET-pf DHFR-TSΔ229-274 | 74.4 ± 18.5 | 0.9 ± 0.2 | 3487.8 ± 213.2 | 35.8 ± 2.4 |
5. pET-pf DHFR-TSΔ229-275 | 66.7 ± 7.3 | ND | 4719.3 ± 391.3 | ND |
6. pET-pf DHFR-TSΔ229-276 | 83.9 ± 1.0 | ND | 3357.8 ± 443.3 | ND |
7. pET-pf DHFR-TSΔ229-277 | 82.1 ± 3.0 | ND | 3137.8 ± 210.3 | ND |
8. pET-15b | 3.1 ± 0.1 | ND | - | - |