1. PROTEINS

2. VERY GENERAL INFO Amongst all the macromolecules, protein is present more than 50% in living organisms. Your body makes more than 100 000 different types of proteins! Examples: insulin with 51 a.a. & titine (protein in muscle) with 30 000 a.a.

3. Roles of proteins Protection: Antibody Regulation: Many hormones and communication: receptors proteins mOuvement: myosin & actin in muscles & cilia and flagella Transport: hemoglobin, transport across cell membrane Energy: food Influx Nerveux: rhodopsine is a photoreceptor Enzymes: for all the chemical rxn in the organism Structure: exokeletton, keratine – hair, horns, feathers

4. General structure of amino acids http://www.hcc.mnscu.edu/programs/dept/chem/V.27/amino_acid_structure_2.jpg

6. PROTEIN STRUCTURE Primary structure : Sequence of a.a. Held together by peptide bonds (btw carboxyl group of 1 a.a. and amino group of other a.a. http://www.mcat45.com/content/protein

7. Secondary structure: Coils and folds in chain - α helix : in α-keratin (hair) - β-pleated sheet: in silk of spider’s web Held together by hydrogen bonds btw a.a. close to each other or parallel (btw carboxyl and amino group)

8. Alpha-helix http://www.denizyuret.com/students/vkurt/thesis-main.htm

9. ß sheet http://fig.cox.miami.edu/~cmallery/255/255prot/255proteins.htm

10. Tertiary structure: Global folding or further fold due to water interactions and stabilized by R-group interactions. - Polar R group: serine, tyrosine, glutamine, threonine, cysteine, asparagine (goes towards water / exterieur) - Non polar R group: valine, phenylalanine, glycine, alanine, leucine, isoleucine, methionine, tryptophan, proline (hydrophobic / goes interieur) - R-group interactions: hydrogen bonds, ionic bonds, disulfide bonds btw cysteine & van der Waals forces

11. Tertiary structure http://kvhs.nbed.nb.ca/gallant/biology/tertiary_structure.jpg

12. Quaternary structure: In some protein, 2 or + polypeptide chains come together. May also have heme group Ex: collagen, keratin, haemoglobin (2 α- chains + 2 β-chains + 4 heme groups with iron) Stabilized by H-bond, van der Waals, ionic bonds and rarely disulfide bonds

13. http://www.contexo.info/DNA_Basics/Protein_Structure.htm

14. Hemoglobin http://www.mcat45.com/content/protein