1. Levels of Protein Structure 16.5

2. Peptide/Protein Formation Peptide: small, up to 50 AA Proteins: large, several 100 AA and/or multiple peptide chains grouped together Ribosomes translates m-RNA into AA sequence: 3 nucleotide = 1 AA

3. 1 o Primary Structure Number and order of AA Reflected by peptide name Example: Alanylglycylserine 1 o structure is the basis for all other levels of peptide/protein structure

4. 2 o Secondary Structure Interaction between Amino- and Carboxyl groups residues from the peptide backbone forming H-Bonds N-H…….O=C

5. a)Alpha Helix b) Beta pleated sheet collagen, woolsilk

6. 3 o - Tertiary Structure Governed by R-side chain interactions 1.Hydrophobic interactions: At the center of a protein – two non-polar side chains are attracted (Ex: Ala and Leu) 2. Hydrophilic interactions: at the outskirts of a protein – two polar side chains, H-bonds (Ex: Ser with Thr)

7. 3 o structure 3. Salt Bridges (ionic bonds): attraction between acidic and basic side chains (Ex: Lys with Glu) 4. Disulfide Bridges: -S-S- covalent bond formation, two Cystein react, stabilizes the 3-D confirmation of large proteins, strongest

9. 4 o – Quaternary Structure Multiple peptide chains aggregate together to form a large functional unit Governed by R-side chain interactions (see 3 o structure…) Not all proteins have it

11. Globular Proteins Have a compact, spherical 3-D shape Very stable, function as enzymes and transport molecules Hemoglobin Enzyme

12. Fibrous Proteins Long, thin, fiber like shapes Used as structural components: wool, skin, scales, feathers keratin collagen

13. Denaturation Change in 3-D structure of a protein when exposed to heat/acids/bases/heavy metals/ organic solvents/agitation Disrupts all levels of protein structure Exception: Dissulfide bridges remain, or new ones form…

14. Denaturation

15. Homework Pgs 550 – 551 #16.22 – #16.34 (even) Skip #16.28 Print the Enzyme Lab