Compare7 marksChallenge
Two enzymes, lactase (from E. coli) and cellulase (from Trichoderma reesei), catalyse the hydrolysis of different substrates. Their kinetic parameters are shown in the table.
| Enzyme | Substrate | Km (mM) | Vmax (μmol min⁻¹ mg⁻¹) |
|---|---|---|---|
| Lactase | lactose | 0.5 | 120 |
| Cellulase | cellulose | 2.5 | 80 |
Compare the affinities of these two enzymes for their respective substrates. Explain the relationship between Km and enzyme–substrate affinity. Predict how the addition of a competitive inhibitor would affect the measured Km and Vmax for lactase, and justify your prediction.