TABLE 3.
Effect of aromatic amino acids on wild-type and mutant AtCM1
Reactions were performed as described under “Experimental Procedures.” Conversion of chorismate to prephenate by wild-type and mutant AtCM1 was determined while varying each amino acid concentration. All parameters are expressed as an average ± S.E. for an n = 3.
| EC50 | Apoenzyme Vmax | Fully bound Vmax | |
|---|---|---|---|
| μm | μmol min−1 mg protein−1 | μmol min−1 mg protein−1 | |
| Phenylalanine | |||
| AtCM1 | 50.0 ± 4.7 | 26.0 ± 0.6 | 1.2 ± 1.0 |
| R79K | 340 ± 100 | 39.0 ± 0.4 | 16.0 ± 2.6 |
| H145Q | 160 ± 31 | 5.4 ± 0.1 | 1.0 ± 0.2 |
| G213P | 22.0 ± 0.5 | 19.1 ± 0.3 | |
| G213A | 23.9 ± 1.4 | 24.8 ± 0.3 | |
| V217T | 240 ± 65 | 39.4 ± 0.6 | 0 |
| Tyrosine | |||
| AtCM1 | 11.0 ± 1.3 | 28.6 ± 0.6 | 1.4 ± 0.6 |
| R79K | 110 ± 40 | 37.8 ± 0.6 | 7.4 ± 3.2 |
| H145Q | 230 ± 100 | 4.4 ± 0.1 | 0.2 ± 0.8 |
| G213P | 22.0 ± 0.5 | 18.9 ± 0.5 | |
| G213A | 23.9 ± 1.4 | 22.3 ± 1.7 | |
| V217T | 50.0 ± 11 | 40.0 ± 1.0 | 0 |
| Tryptophan | |||
| AtCM1 | 2.6 ± 0.5 | 29.4 ± 0.6 | 55.0 ± 1.0 |
| R79K | 1.6 ± 0.4 | 40.0 ± 1.4 | 78.0 ± 2.0 |
| H145Q | 7.2 ± 0.8 | 6.4 ± 0.2 | 30.8 ± 0.6 |
| G213P | 22.0 ± 0.5 | 21.6 ± 1.9 | |
| G213A | 23.9 ± 1.4 | 20.9 ± 0.2 | |
| V217T | 2.4 ± 0.5 | 31.4 ± 0.7 | 69.0 ± 1.4 |