1. Proteins are made up of carbon, hydrogen, oxygen and nitrogen.
2. Protein contains sulphur, phosphorus, iron and copper.
3. Changes in the physical and chemical nature of proteins.
4. Proteins are tasteless or colorless biochemical substances.
5. Some proteins are soluble in water and some are soluble in salt.
6. Some dissolve in alkali or acid solution and some in alcohol solution.
7. Proteins are colloidal in nature.
8. Proteins are large and high molecular weight organic compounds.
9. Their molecular weight is 5,000-50,000,000 daltons. The molecular weight of insulin is 6,000 daltons.
10. Hydrolysis of proteins by proteolytic enzymes yields amino acids.
11. Proteins are amphoteric because they contain basic groups and acidic groups. It is called an amphoteric protein for having both acidic and alkaline properties.
12. Addition of ninhydrin to the protein solution gives a red color when heat is applied.
13. Application of acid causes proteins to precipitate or coagulate and change molecular structure.
14. It acts as an electrolyte or buffer solution.
15. Proteins are precipitated in magnesium sulfate and sodium sulfate solutions.
16. Protein breaks down in the presence of oxygen to produce NH3, CO2 and H2O.
17. Proteins can be degraded in different ways.