TABLE 4.
Steady-state kinetic parameters of SAT and the CSC
All reactions were performed as described under “Experimental Procedures.” The KI value for serine was determined by fitting data to the equation for substrate inhibition. The KI value for serine was determined by fitting data to the equation for non-competitive inhibition. All values are expressed as the mean ± S.E. for n = 3.
| SAT | CSC | |
|---|---|---|
| V/Et (s−1) | 95.6 ± 5.1 | 165 ± 3 |
| Kmacetyl-CoA (μm) | 290 ± 60 | 46 ± 4 |
| kcat/Kmacetyl-CoA (m−1 s−1) | 330,000 | 2,590,000 |
| Kmserine (μm) | 430 ± 60 | 700 ± 20 |
| kcat/Kmserine (m−1 s−1) | 222,000 | 236,000 |
| KIserine (μm) | 8,000 ± 1,000 | |
| KIcysteine (μm) | 2 ± 0.1 | 70 ± 10 |