Enzymes are affected by various factors which influence their action and effectiveness.
These factors can alter the rate of reaction by affecting the enzyme's protein structure.
Key conditions include temperature, pH, substrate concentration, enzyme concentration, and inhibitors.
Temperature
Low Temperature: Reduces kinetic energy; fewer successful collisions between enzyme active sites and substrates, leading to fewer enzyme-substrate complexes.
High Temperature: Beyond the optimum, enzymes denature. Denaturation involves the active site changing shape due to broken bonds in the enzyme's tertiary structure.
pH
High or Low pH: Causes denaturation as ionic and hydrogen bonds break. Excessive H⁺ or OH⁻ ions interfere with amino acid charges, altering the enzyme's 3D shape.
Optimal pH: Varies among enzymes depending on their natural environment (e.g., amylase is slightly alkaline, proteases are acidic).
Substrate and Enzyme Concentration
**Substrate Concentration: **
Low concentrations limit the rate of reaction due to insufficient substrate available for collisions.
Increased concentration leads to a plateau when the enzyme concentration becomes the limiting factor.
**Enzyme Concentration: **
Low concentrations limit the rate due to saturation of active sites.
Increased concentration results in a plateau due to a lack of substrates to utilize active sites.
Inhibitors
Inhibitors are molecules that bind to enzymes and prevent function.
Competitive Inhibitors:
Similar in shape to substrates, bind to active sites forming enzyme-inhibitor complexes.
High substrate concentrations can outcompete inhibitors, restoring reaction rates.
Non-Competitive Inhibitors:
Bind away from the active site (allosteric sites), altering enzyme's 3D shape and active site.
Substrate cannot bind even at high concentrations; the reaction rate remains low.
Graphical Representation
Competitive Inhibitor:
Causes a lower reaction rate initially, but at high substrate concentrations, the reaction rate aligns with uninhibited reactions.
Non-Competitive Inhibitor:
Results in a consistently lower reaction rate that plateaus due to the inability of substrates to bind.
Conclusion
Understanding how temperature, pH, substrate and enzyme concentration, and inhibitors affect enzyme action is crucial for predicting and controlling biochemical reactions.