Tertiary structure 3 2 1 3 4 Interactions
- Slides: 7
Tertiary structure (3˚) 2) 1) 3) 4) • Interactions between the side chains / “R groups” • Protein folding shown in Hippocampus program • Order of strength: 1. Peptide bond (covalent) 2. Disulphide bond (covalent) 3. Ionic bond 4. Hydrogen bond 5. Hydrophobic interactions
Quaternary structure (4˚) • 2 or more polypeptide chains joined together
Polarity & Hydrophilic/phobicity • “Hydro” in hydrophobic/hydrophilic refers to Water, which is POLAR • Therefore polar R groups of amino acids will be hydrophilic as it will be able to hydrogen bond with water molecules. • Non-polar R groups of amino acids will be hydrophobic because the hydrophobic R groups would repel the polar water molecules
Free or Anti-social in Water (polar)? Anti-social: Don’t want anything to do with water molecules Freely interacting with water molecules Bond to each other {
Free or Anti-social in Oil (non-polar)? Freely interacting with oil molecules Anti-social: Don’t want anything to do with oil molecules Bond to each other {
Denaturation of proteins • Permanently changes the 3 D structure of protein • Caused by external stress: -Temperature -Acid/Alkaline -Concentrated inorganic salt -Organic solvent
Functions of Proteins • Support structure: e. g. cytoskeleton, cartilage, bone • Enzymes: catalyze reactions • Monitors: changing shape according to signals • Intercellular communication