BIOCHEMISTRY - Textbook - Ostapchenko L. I. - 2012

Chapter 7. ENZYMOLOGY

7.5. Fundamentals of Enzymatic Reaction Kinetics

7.5.2. Dependence of Enzyme Reaction Rate on Ambient Temperature

Raising the Temperature up to a certain limit affects The rate of an enzymatic reaction similarly to its effect on any chemical reaction. As the temperature rises, molecular motion accelerates, increasing the probability of interaction between reactants. In addition, temperature can increase the energy of reacting molecules, which also speeds up the reaction. However, the rate of an enzyme-catalyzed chemical reaction has its own temperature optimum; exceeding this threshold leads to a decline in enzymatic activity caused by the thermal Denaturation of the protein molecule (Fig. 7.17).

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Fig. 7.17. Dependence of enzyme reaction rate (V) on temperature

For most human Enzymes, the optimal temperature is 37-38 °C. However, thermostable enzymes also exist in nature. For instance, Taq polymerase, isolated from microorganisms living in hot springs, is not inactivated when temperatures rise up to 95 °C. This enzyme is utilized in research and practical medicine for the molecular Diagnosis of diseases using the Polymerase Chain Reaction (PCR) method.