What are the substances of the protein structure known to you? Where are they found in the body?

Collagen. It is a structural protein of bones, tendons, ligaments and skin. Collagen differs from all other proteins in its high content of proline and hydroxyproline.

Muscle proteins. The total amount of muscle proteins in mammals, including humans, exceeds that of other proteins. About 40 percent of the body weight of a healthy adult is muscle, which is made up of approximately 20 percent muscle protein.

Fibrinogen and fibrin. Fibrinogen, a blood plasma protein, is converted to the insoluble fibrin protein during the blood clotting process.

Albumin, globulins and other soluble proteins. Blood plasma, lymph, and other fluids typically contain one to seven grams of protein per 100 milliliters of fluid.