Demonstrate the properties of proteins and the effect of pH on protein solubility with this colorful and reversible activity. Proteins contain many acidic and basic groups that have different structures at different pH values. When acids and bases are added to a protein solution, the solubility of the protein changes drastically. This demonstration looks at the acid-base and solubility properties of casein, the main protein in milk. The structure of the protein at different pH values is discussed. Teacher Demonstration Notes included. Enough materials are included to perform the demonstration seven times.
Concepts: Proteins, isoelectric point, solubility, pH.
Time Required: 15 minutes
Chemicals Provided: Casein, hydrochloric acid solution, sodium hydroxide solutions, universal indicator.
Additional ResourcesNo Additional Resources at the time.
Flinn Catalog/Reference Manual Page 400
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