Here's why:
* Enzymes are catalysts: They speed up reactions without being consumed in the process.
* Equilibrium: Enzymes do not change the equilibrium point of a reaction. They simply make the reaction reach equilibrium faster.
* Product inhibition: While some enzymes can be inhibited by the products of their own reaction, this is a separate phenomenon and not a fundamental limitation.
Factors that DO affect enzyme activity:
* Substrate concentration: Higher substrate concentration generally leads to increased reaction rate until the enzyme is saturated.
* Temperature: Enzymes have optimal temperatures. Too high or too low temperatures can denature the enzyme and reduce its activity.
* pH: Each enzyme has an optimal pH range. Extremes of pH can denature the enzyme.
* Presence of inhibitors: Some molecules can bind to and inhibit the enzyme's activity.
* Presence of activators: Some molecules can bind to and activate the enzyme's activity.
