Proteins

Definition

Macromolecules build of aminoacids (aa). They are polymers. A typical protein contains 200-300 aminoacids. The smallest proteins are called peptides. The longest one is called titin, found in the skeletal and cardiac muscle. It contains 34350 aa in a single chain.

Unit of monomer: aminoacid (aa).

Function

1. Energetic: 4 kcal/g.
2. Catalyzer.
3. Regulation: Hormones, neurotransmitters.
4. Transportation: Hemoglobin, albumin.
5. Structure: Collagen, keratin.
6. Contractile: Actin, myosin.
7. Defensive: Immunoglobulin.
8. Reserve: Ferritin.

Structure

1. Primary: Specific sequence of amino acids in the protein.
2. Secondary: Specific geometric shape due to some hydrogen bonding of amide groups, because the interaction between H-bonds. Two types: Alpha helix, Beta sheet.
3. Tertiary: Final specific geometric shape that a protein assumes. This final shape is determined by a variety of bonding interactions stronger than the hydrogen bonds between the "side chains" of the aminoacids.
4. Quaternary: It involves the clustering of several individual peptides or proteins chains into a final specific shape.

Denaturation process: It is when a protein loses its original structure by: an alcohol, acid of heat.

Sources: tuna, chicken breast, lean ground beaf, non fat milk, tofu, lentils, cheese, albumin.

Recommended diet:

• 45-65% carbohydrate
• 20-35% fat
• 10-35% protein