Weak Binding of Substrates
- Although binding of substrate to enzyme is a major contributor to the rate increase, it's important
that the substrate not bind too tightly. Excessive ES stability actually prevents attainment of the
transition state, ES*
- This excess stability is called a thermodynamic pit, as can be seen in a free energy reaction curve:
- Consequently, the Km values of enzymes have evolved to reach an optimum between weak binding
and excessive binding stability of substrate