1. PROTEINS

2. Introduction Greek “proteois” : primary Most diverse of all macromolecules Most can be made in the body Essential Amino Acids: body cannot synthesize de novo, must be consumed (12 for children, 8 for adults)

3. USES Structural building blocks of cells/organelles Hormones, pigments, carriers, cell machinery, chaperones, receptors… Hair, skin, feathers, nails, cartilage, bone, tendons, muscle, anti-bodies, blood clots… Enzymes Make up 50% of human body’s dry weight (Last) source of energy

4. STRUCTURE Sequence of amino acids 20 amino acids varieties (20aa) FG 1: carboxyl FG 2: amino Can be 100s-1000s of units long

5. VARIABILITY Variability of the sequence is dependent on the # of aa in the chain Variability = 20 n where n = # of aa Ex: A polypeptide that contains 8 aa has a variability of: 20 8 = 2.56 x 10 10

6. CLASSIFICATION OF AA Dependent on “R” group 1) POLAR: OH, SH, NH 2 +//O 2) NON-POLAR: CH 2, CH 3 3) CHARGED: -/+ **Note: cysteine is the only one that contains a sulfhydryl fg.

7. …CLASSIFICATION OF AA See Page 26

8. …CLASSIFICATION OF AA HYDROPHILIC: polar, charged –e.g. lysine, arginine, serine HYDROPHOBIC: non-polar –e.g. isoleucine, valine Properties of R-groups determine the tertiary structure

9. …Learning the AA (for the test)… You do NOT have to know the names of all 20 amino acids You DO have to know 2 specific ones: cysteine and proline bc of their unique structure and properties You DO have to be able to classify an aa as polar, non-polar or charged if you are given the structure

10. LINKING AMINO ACIDS Condensation rxn Forms a peptide bond (C-N) Also called amide linkage: 2aa joined: dipeptide Many aa joined: polypeptide *notice rxn occurs b/w fgs

11. PEPTIDE BOND

13. PRIMARY 1º Basic polypeptide sequence, linear

14. SECONDARY 2º 1) α -helix: –Coil held together by H- bonds –3.6 aa per turn 2) β -sheet –Strands lie adjacent to one another –Held together by H-bonds

15. TERTIARY 3º Helices and β-sheets supercoil o Ionic bonds o H-bonds o Hydrophobic interactions o Disulfide bridges (cys-cys), strong stabilizers, covalent

17. QUATERNARY 4º Polypeptide interacting with one or more polypeptides

18. DENATURATION Change in shape of protein, may unravel or breakdown High/low pH Heat Radiation Example: egg white: transparent  white

19. PRACTICE QUESTIONS Are amino acids organic compounds? Which aa is involved in disulfide bridges? ESTER is to lipids like _____ is to proteins What types of interactions hold 3º the structure together? Need to know classification of aa

20. HOMEWORK Read Page 25-27 –Tertiary structure, Proline –Denaturation –Hair –Hemoglobin –Chaperone proteins Worksheet -