Table 3.
Dissociation/inhibition constants for wild-type and mutant aminotransferases
| MaleateaKD (mM) | HydrocinnamateaKD (mM) | |
| Aspartate Aminotransferases | ||
| WTb | 19 (1) | >75 |
| T109Sc | >150 | 44 (1) |
| N297Sb | 19 (1) | 25 (26) |
| T109S/N297Sc | >100 | 28 (1) |
| Tripb | 1.9 (0.1) | 15 (8) |
| Grease | 0.2 (0.01) | 3.8 (0.2) |
| Hexb | 0.44 (0.12) | 0.12 (0.03) |
| Tyrosine Aminotransferases | ||
| WTb | 140 (10) | 12 (0.4) |
| S109Tc | 8.7 (0.4) | 10.9 (0.4) |
| S297Nc | >400 | 33 (2) |
| S109T/S297Nc | 39 (2) | 25 (1) |
| retroGrease | N.B. | 20 (2) |
| retroHexd | 30 (2) | 3.5 (0.3) |
(N.B.) No binding observed.
aKD values were determined by spectrophotometric titration (see Materials and Methods). Conditions: Grease AATase and retroGrease TATase: 0.2 M TAPS at pH 8.0; 0.14 M KCl; [Hca] = 0–40 mM. [maleate] = 0–30 mM. [Enzyme] = 31 μM. 25°C. Values reported are weighted averages from three experiments. retroHex TATase: Ki values determined as described in Materials and Methods. Conditions: 20 mM K phosphate at pH 7.5; Ic = 0.1 M (KCl). [Asp] = 1 mM, [αKG] = 8 mM. [maleate] = 0–40 mM. [Hca] = 0–4 mM. [MDH] = 0.32 nM. 25°C.
b From Onuffer and Kirsch (1995).
c From Luong and Kirsch (2001).
dKi values reported.