Biology – 5.1 Enzymes | e-Consult

The observation that the reaction rate increases with temperature up to a certain point, then rapidly decreases, can be explained by the relationship between enzyme specificity, enzyme structure, and temperature.

At low temperatures, the enzyme molecules have less kinetic energy, resulting in fewer collisions between the enzyme and substrate. This means the reaction rate is slow.

As the temperature increases, the enzyme molecules gain kinetic energy and collide more frequently with the substrate. This leads to more successful binding and a higher reaction rate. However, there is an optimal temperature at which the enzyme functions most efficiently. This optimal temperature corresponds to the temperature at which the enzyme's three-dimensional structure is maintained.

Above the optimal temperature, the enzyme molecules begin to denature. Denaturation refers to the unfolding of the enzyme's protein structure. This is due to the disruption of the weak bonds (hydrogen bonds, ionic bonds, and hydrophobic interactions) that maintain the enzyme's specific shape. As the enzyme denatures, the active site loses its precise shape and can no longer bind to the substrate effectively. Therefore, the reaction rate rapidly decreases.

This demonstrates that enzyme specificity is directly linked to the enzyme's structure. Temperature affects the stability of this structure, and extreme temperatures can lead to irreversible denaturation, rendering the enzyme inactive.