TABLE 2.
Kinetic parameters of the wild-type and P and Q mutant TcLDHs for substrate pyruvate
The parameters were determined as described under “Experimental Procedures,” and standard deviations are shown in parentheses.
| S0.5 | Vmax | Vmax/S0.5 | nH | |
|---|---|---|---|---|
| mm | units/mg | units/mg/mm | ||
| − FBP | ||||
| Wild type | 36 (7) | 11 (1) | 0.29 | 1.4 (0.1) |
| I67E/H68D (Q2) | 24 (1) | 43 (1) | 2.81 | 2.4 (0.1) |
| I67E/H68D/E178K (Q3) | 20 (1) | 31 (0.3) | 1.40 | 1.8 (0.1) |
| I67E/H68D/E178K/A235K (Q4(K)) | 9.3 (0.4) | 47 (1) | 5.1 | 1.6 (0.1) |
| I67E/H68D/E178K/A235R (Q4(R)) | 7.3 (0.8) | 40 (1) | 5.5 | 1.6 (0.1) |
| R173Q (P1) | 3.2 (0.2) | 10.6 (0.4) | 3.3 | 1.3 (0.1) |
| R173Q/R216L (P2) | 0.33 (0.10) | 9.6 (1.2) | 29 | 0.8 (0.1) |
| Q4(K)/P1 | 0.93 (0.02) | 27.1 (0.3) | 29 | 1.4 (0.1) |
| Q4(R)/P1 | 0.76 (0.04) | 40.0 (0.9) | 53 | 1.3 (0.1) |
| Q4(K)/P2 | 0.26 (0.02) | 43.4 (1.3) | 167 | 1.1 (0.1) |
| Q4(R)/P2 | 0.079 (0.03) | 41.0 (0.5) | 520 | 1.0 (0.1) |
| + FBP | ||||
| Wild type | 0.040 (0.002) | 40.1 (1.3) | 1000 | 1.2 (0.1) |
| I67E/H68D (Q2) | 0.13 (0.01) | 41.9 (0.8) | 322 | 1.1 (0.1) |
| I67E/H68D/E178K (Q3) | 0.50 (0.08) | 75.7 (5.5) | 151 | 0.9 (0.1) |
| I67E/H68D/E178K/A235K (Q4(K)) | 0.075 (0.003) | 45.1 (0.8) | 601 | 1.2 (0.1) |
| I67E/H68D/E178K/A235R (Q4(R)) | 0.041 (0.002) | 51.4 (0.9) | 1250 | 1.1 (0.1) |