effect of temperature

Effect of Temperature on Enzymes

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Due to proteinaceous nature, enzymes are very sensitive to heat. The rate of an enzyme action increases with rise in temperature, the rate of action increases 2 to 3 times for a rise in temperature of 10°C, i.e., the value of temperature quotient or Q₁₀ is 2 to 3. But at higher temperatures, the value of coefficient does not remain constant and decreases rapidly. Above 60°C, the enzymes coagulate and thus become inactivated due to irreversible change in their chemical structure.
With certain exceptions, the rates of enzymes catalyzed reaction are increased as the temperature is raised. By raising temperature, the number of activated molecules is increased which ultimately results in velocity of the reaction. The enzyme catalyzed reactions show the increase in the velocity between 25°C to 35°C. At 0°C or below 0°C the enzymes become inactivated but they are not destroyed. At 60°C to 70°C, in a liquid medium the enzymes are inactivated and destroyed. This destruction of enzymes at high temperature results in coagulation and denaturation. Thus as the temperature is raised, the reaction rate increases upto a certain limit and above that the enzymes get denatured. The temperature, at which the rate of reaction in maximum, is known asoptimum temperature.

Effect of temperature on enzymes-Graph (temperature vs enzyme activity)