BRAINCAKEEffect of pH
Each enzyme works fastest at a particular pH, its optimum pH. Most intracellular enzymes have an optimum near pH 7, but some differ:
• pepsin, a protease in the stomach: about pH 2
• salivary amylase: about pH 7
• trypsin in the small intestine: about pH 8
pH is a measure of the concentration of hydrogen ions (H+). A change in pH changes the H+ concentration, which affects the enzyme in two ways:
• it alters the charges on the R groups of amino acids in the active site, so the substrate may no longer bind or the reaction may not be catalysed
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Key terms in this lesson
- buffer solution
- A solution that resists changes in pH when small amounts of acid or alkali are added.
More in Enzymes
- Induced Fit Hypothesis
- Measuring Rate of Reaction
- Effect of Substrate Concentration
- Effect of Temperature
- Effect of Enzyme Concentration
- Reversible and Irreversible Inhibition
- Competitive Inhibition
- Non-competitive Inhibition
All 14 lessons in Enzymes · All Edexcel AS-level Biology topics