Intro to Enzymes: Videos & Practice Problems

Enzymes are proteins that act as catalysts in biochemical reactions, meaning they speed up these reactions without being consumed or altered in the process. They function by lowering the activation energy (E_a), which is the minimum energy required for a reaction to occur. This is achieved when the substrate, a smaller reactant molecule, binds to the enzyme's active site, forming an enzyme-substrate complex. This interaction facilitates the transformation of the substrate into products, making the reaction proceed more quickly and efficiently. Importantly, the enzyme remains unchanged after the reaction, ready to catalyze subsequent reactions.

The substrate is the reactant molecule that binds to the enzyme's active site in enzyme-catalyzed reactions. It is typically much smaller than the enzyme. When the substrate binds to the enzyme, they form an enzyme-substrate complex. This complex facilitates the transformation of the substrate into products. The enzyme provides a specific environment that lowers the activation energy (E_a) required for the reaction, thereby speeding up the process. After the reaction, the substrate is converted into products, and the enzyme remains unchanged, ready to catalyze another reaction.

Enzymes lower the activation energy (E_a) of a reaction by providing an alternative reaction pathway with a lower energy requirement. When a substrate binds to the enzyme's active site, it forms an enzyme-substrate complex. This complex stabilizes the transition state and reduces the energy needed to convert the substrate into products. By lowering the activation energy, enzymes increase the rate of biochemical reactions, making them proceed more quickly and efficiently. Importantly, the enzyme itself is not consumed or altered during this process.

After an enzyme catalyzes a reaction, it remains unchanged and is not consumed in the process. The enzyme starts by binding to the substrate to form an enzyme-substrate complex, facilitating the transformation of the substrate into products. Once the reaction is complete, the products are released, and the enzyme returns to its original state. This allows the enzyme to participate in multiple reaction cycles, continuously catalyzing the same type of reaction without being altered or depleted.

An enzyme-substrate complex is a temporary molecular structure formed when a substrate binds to the active site of an enzyme. This complex is crucial because it stabilizes the transition state of the reaction, thereby lowering the activation energy (E_a) required for the reaction to proceed. The formation of the enzyme-substrate complex facilitates the conversion of the substrate into products, making the biochemical reaction more efficient and faster. Once the reaction is complete, the products are released, and the enzyme remains unchanged, ready to catalyze another reaction.