Explain5 marksStandard
The effect of two different reversible inhibitors, I1 and I2, on the activity of an enzyme was investigated. Initial rates of reaction were measured at various substrate concentrations in the absence of inhibitor and in the presence of a fixed concentration of each inhibitor. The results are shown in Table 1.
Table 1: Initial rate (arbitrary units) at different substrate concentrations
| [Substrate] / mmol dm | No inhibitor | With I1 | With I2 |
|---|---|---|---|
| 0.2 | 4 | 2 | 3 |
| 0.5 | 10 | 5 | 10 |
| 1.0 | 18 | 9 | 18 |
| 2.0 | 28 | 15 | 21 |
| 5.0 | 38 | 26 | 22 |
| 10.0 | 42 | 41 | 22 |
Explain how the results in Table 1 distinguish between competitive and non-competitive inhibition. In your answer, refer to the changes in Vmax and the Michaelis constant (Km).