Table 1.
Folate-binding and steady-state kinetic parameters
Reported uncertainties are standard errors as calculated from curve fitting in Origin 2019. ND, not determined.
| Essex SHMT8 | Forrest SHMT8 | |
|---|---|---|
| Spectrophotometric FTHF-binding assay | ||
| SHMT8·glycine + FTHF (μm) | 17 | ND |
| Steady-state kinetics: MTHFD-coupled reaction | ||
| kcat (s−1) | 14 ± 3 | ND |
| Km,THF (μm) | 30 ± 11 | ND |
| Km,Ser (μm) | 240 ± 30 | 1300 ± 200 |
| Ki,THF (μm) | 170 ± 70 | |
| kcat/Km,THF (mm−1 s−1) | 500 ± 190 | 0.22 ± 0.02a |
| Steady-state kinetic parameters: retro-aldol cleavage of l-phenylserine | ||
| kcat (s−1) | 1.3 ± 0.1 | 0.93 ± 0.04 |
| Km (mm) | 70 ± 10 | 63 ± 5 |
| kcat/Km (m−1 s−1) | 18 ± 3.3 | 15 ± 1.3 |
a Catalytic efficiency approximated from linear regression.