Final answer:
Enzymes maintain reaction equilibrium by lowering activation energy and correctly orienting substrates without altering the free energy of reactants or products. They work repeatedly as long as substrate is available but can become saturated. Specific enzymes for reversible reactions allow better metabolic control.
Step-by-step explanation:
In order to maintain reaction equilibrium, enzymes play a crucial role by providing a platform where reactants, or substrates, can come together more efficiently. Enzymes lower the activation energy that's necessary for reactions to occur, which doesn't change the overall free energy of the reactants or products but makes the reaction proceed more readily. They achieve this by binding to the substrates at the active site, correctly orienting them, and by potentially providing an alternative reaction pathway with a lower activation energy.
Enzymes remain unchanged throughout the course of the reaction, enabling them to repeatedly bind with new substrate molecules. When the concentration of substrate is high enough, it may reach a point where all enzymes are occupied, and the reaction rate will no longer increase due to enzyme saturation. In other words, enzymes work most efficiently when they can persistently catalyze reactions without reaching a stalling state due to equilibrium.
For reversible reactions, enzyme specificity for each direction of the reaction can prevent equilibrium from being rapidly reached, allowing the organism to better control the flow of biochemical pathways. This enzyme-mediated control is essential for the proper regulation of metabolism and other biological processes.