L5 - Enzymes and pH

objectives

• Explain the effect of changes in temperature and pH on enzyme activity
• Examples of enzymes include Proteases, lipases, amylases and their functions

pH

pH is the measure of how acidic or alkaline a solution is.

A pH of below 7 is considered acidic

A pH of above 7 is considered alkaline

A pH of 7 is considered neutral

In the body there are places that have different pH's including the mouth, stomach and gut. Different enzymes operate better at different pH because of their location in the body.

Each enzyme has a different optimum pH. On either side of the optimum, the enzyme is denatured and rate of reaction decreases - just like with temperature in the previous section.

Pepsin is found in the stomach, Amylase is found in our mouths (in the saliva) and lipase is found in the pancreas. You can see that these operate at different pH.

Catalase

Hydrogen peroxide (H₂0₂) is a product of metabolism. It is toxic and so it must not be allowed to build up in cells. The enzyme catalase protects cells by breaking down hydrogen peroxide into the harmless products water and oxygen: