Curves T1 and T2 show the distribution of kinetic energies for gaseous molecules at two different temperatures. Curve T2 is positively skewed because it represents a higher temperature. Hence, the peak of the graph with the most molecules is shifted towards a higher kinetic energy value and the curve broadens out. For both cases, the total area under the curve is the same; nevertheless the fraction of molecules with energy greater than the activation energy (EA) is much larger in T2 than T1. Thus, when temperature increases, more substrate particles have sufficient energy to react thus more products are formed at a given unit of time.
Furthermore, the Arrhenius equation,
k = Ae(-Ea/RT)
shows the relationship between the rate constant, k, and absolute temperature. A and R are constants; therefore it is assumed that the rate of reaction is proportional to e(-Ea/RT) and increases when temperature, T, increases.
However, since enzymes are proteins, they can be considered fragile. If the temperature becomes too high, the amino acids in the enzyme protein will vigorously vibrate to break intramolecular bonds. Then, the enzyme denatures, meaning the structure of the protein has irreversibly changed so that the substrate no longer fits into the active site, making it functionless. This denaturation point is when the temperature of the enzyme immediately exceeds the optimum temperature and starts decreasing the rate of reaction in response to increasing temperature. The hypothesis is that 37°C will be the optimum temperature where catalase activity will occur at the fastest rate because the human body also functions its best at 37°C. Once the temperature of catalase exceeds 37°C, it will denature and H2O2 molecules probably cannot fit into the active sites and start decreasing the rate of reaction as shown in Figure1. Perhaps from approximately 50°C, there may be no reaction at all, for by then, all catalase will be entirely denatured.
