Which factor decreases enzymatic speed?

Which factor decreases enzymatic speed?

• A. Substrate concentration
• B. Rising temperature
• C. Loss of electrons
• D. pH

Answer: (D)

Enzymes rely on the right protonation states of amino acids in the active site to bind substrate and carry out catalysis. The pH determines which groups are protonated or deprotonated, so changing pH away from the enzyme’s optimum disrupts these charges, alters hydrogen bonding and electrostatic interactions, and can distort the active site. This reduces binding affinity and catalytic efficiency, slowing the reaction or stopping it if the structure becomes unstable. Substrate concentration tends to increase speed up to saturation, higher temperatures can raise speed until denaturation occurs, and loss of electrons isn’t the typical driver of rate changes in this context. Thus, pH deviations from the optimum directly decrease enzymatic speed.

Enzymes rely on the right protonation states of amino acids in the active site to bind substrate and carry out catalysis. The pH determines which groups are protonated or deprotonated, so changing pH away from the enzyme’s optimum disrupts these charges, alters hydrogen bonding and electrostatic interactions, and can distort the active site. This reduces binding affinity and catalytic efficiency, slowing the reaction or stopping it if the structure becomes unstable. Substrate concentration tends to increase speed up to saturation, higher temperatures can raise speed until denaturation occurs, and loss of electrons isn’t the typical driver of rate changes in this context. Thus, pH deviations from the optimum directly decrease enzymatic speed.