Competitive inhibition | Energy and enzymes | Biology | Khan Academy
Understanding Enzyme Catalysis and Competitive Inhibition
Enzyme-Substrate Interaction
- The enzyme catalyzes a reaction by binding to the substrate at its active site, facilitating the conversion of the substrate into products.
- After the reaction occurs, the enzyme remains unchanged while the substrate is transformed into two smaller molecules that no longer bind to the active site.
- The process illustrates how enzymes function as catalysts without being consumed in the reaction.
Competitive Inhibition Explained
- Competitive inhibition occurs when a molecule competes with the intended substrate for binding at the enzyme's active site, preventing catalysis if it binds first.
- If an alternative molecule occupies the active site before the intended substrate can bind, then no reaction will occur due to this competition.
Allosteric Competitive Inhibition
- Allosteric competitive inhibition involves a competitor binding to an allosteric site (not the active site), which alters enzyme conformation and prevents substrate binding at the active site.
- This type of inhibition still results in competition for enzyme access; if either molecule binds first, it prevents the other from accessing the enzyme.
Distinction Between Types of Inhibition
- It’s important to differentiate between competitive and non-competitive inhibition: in non-competitive inhibition, inhibitors can bind regardless of whether a substrate is present but prevent catalysis by altering protein conformation.
- Non-competitive inhibitors do not compete for binding at the active site but affect overall enzymatic activity once bound. Understanding this distinction is crucial for grasping enzymatic regulation mechanisms.