1. Proteins 1 o structureamino acid sequence 2 o structure  - helix  -sheet H-bonding between C=O and N-H of backbone -- ++ some proteins only have 1 o and 2 o structure: fibroin (silk)  -sheet keratin collagen hair skin  - helix insoluble in H 2 O non-polar residues Fibrous

2. Gly-Glu-His- Ala- Phe-Ser- Val-His-Ile-Met-Arg- Asp- Val-Asn- Tertiary structure Primary structuresequence of amino acids Alanine Non-polar Phenylalanine Polar Serine Valine Acidic or Basic Glutamic acid Histidine Isoleusine Methionine Arginine Asperagine Aspartic acid Glycine Ala-Phe-Ser-Ser-Val-Glu-His-Ile-Met-Arg-Asp-Val-His-Asn-Gly

3. Tertiary structure Ala-Phe-Ser-Ser-Val-Glu-His-Ile-Met-Arg-Asp-Val-His-Asn-Gly arrange these in an  -helix Ala 1 Phe 2 Ser 3 4 Val 5 Glu 6 His 7 Ile 8 Met 9 Arg 10 Asp 11 Val 12 His 13 Asn 14 Gly 15 non-polarpolar interior exterior

4. Tertiary structure interaction of the R-groups - - + - + - - + proteins fold around non-polar groups globular proteins hydrophobic residues inside polar and charged residues outside

5. Tertiary structure 1. Hydrophobic interactions non-polar R-groups LDF 2. Hydrogen bonding between H-bond donors and acceptors polar R-groups 3. Ionic bonds(salt bridges)acidic and basic R-groups 4. Covalent bonds (disulfide)cysteins ion-ion interactions of R-groups

6. CH 3 NH + N-terminus C-terminus Pro AlaPheArgAsp Pro S S Cys His - O-CH O = Fe 2+

7. Quaternary Structure subunits hemoglobin heme groups 4 - Fe globin chains 2  -chains 2  - chains held in position by interaction of R-groups polar histidine inside - holds Fe 2+ pK a = 6.1

8. Denaturation form is function loss of native configuration denaturation peptide bonds not affected H-bonds disulfide bonds ionic bonds L.D.F. disrupted

9. Denaturation 4 o structure disrupted firstsubunits separate 3 o structure disrupted protein unfolds 2 o structure disruptedH-bonds broken treatments are sometimes reversible renatured sometimes irreversible insulin

10. Denaturing treatments 1. Heat above 50-60 o C frying egg sunburn 2. pHdisrupt salt bridges approach pH I 3. detergents unfold globular proteins SDS SO 4 - Na + - - + - + - - +

11. Denaturing treatments 4. reducing agents S-S SH HS 5. Metal saltsHg +, Pb +, Ag + S-Hg C = O _ O-O- Hg + 6. H-bonding solvents alcohol acetone 7. “Chaotropes” urea guanidine oxidizing agents

12. Words of Wisdom 3. detergents 6. H-bonding solventsalcohol 1. Heat sunburn