1. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.1 Chapter 20 Enzymes and Vitamins 20.3 Factors Affecting Enzyme Activity

2. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.2 Temperature and Enzyme Action Enzymes  are most active at an optimum temperature (usually 37 °C in humans)  show little activity at low temperatures  lose activity at high temperatures as denaturation occurs

3. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.3 Enzymes  are most active at optimum pH  contain R groups of amino acids with proper charges at optimum pH  lose activity in low or high pH as tertiary structure is disrupted pH and Enzyme Action

4. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.4 Optimum pH Values Enzymes in  the body have an optimum pH of about 7.4  certain organs have enzymes that operate at lower and higher optimum pH values

5. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.5 Enzyme Concentration An increase in enzyme concentration  increases the rate of reaction (at constant substrate concentration)  binds more substrate with enzyme

6. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.6 Substrate Concentration An increase in substrate concentration  increases the rate of reaction (at constant enzyme concentration)  eventually saturates an enzyme with substrate to give maximum activity

7. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.7 Sucrase has an optimum temperature of 37 °C and an optimum pH of 6.2. Determine the effect of the following on its rate of reaction. 1) no change 2) increase 3) decrease A. increasing the concentration of sucrase B. changing the pH to 4 C. running the reaction at 70 °C Learning Check

8. General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.8 Sucrase has an optimum temperature of 37 °C and an optimum pH of 6.2. Determine the effect of the following on its rate of reaction 1) no change 2) increase 3) decrease 2 A. increasing the concentration of sucrase 3 B. changing the pH to 4 3 C. running the reaction at 70 °C Solution