Functional Diversity of Proteins

1. Functional Diversity of Proteins • Catalysis: Enzymes: amylase, pepsin, lipase • Transport: hemoglobin, serum albumin • Structure: keratin, collagen • Movement, Contraction: myosin, actin • Defense: antibodies, fibrinogen • Nutrient and Storage: egg albumin, zein • Regulation: hormones (insulin), repressors

2. Structure Transport Regulation Protein Classification by Function Motion Catalysis Regulation Catalysis Defense Missing Function? Storage

3. Classification of Proteins By Shape Fibrous -insoluble in water Functions: structure, motion High percentage of nonpolar amino acids Globular -usually soluble in water Functions: transport, catalysis, storage Higher percentage of polar and charged amino acids

4. Classification of Proteins By Composition Simple contain only amino acids Examples: amylase, pepsin Conjugated - contain something besides amino acids Examples: Hemoglobin - contains iron Immunoglobin - contains carbohydrate Lactate dehydrogenase - contains niacin

5. -carboxyl group -carbon side chain -amino group

7. Nonpolar Amino Acids

8. Polar, Uncharged Amino Acids

9. Polar, Charged Amino Acids Negatively-charged Positively-charged

10. Serine (Ser) Threonine (Thr) Cysteine (Cys) Aspartic Acid (Asp) Asparagine (Asn) Glutamic Acid (Glu) Glutamine (Gln) Amino Acid Classification: Functional Group Sulfhydryl Alcohol Carboxylic Acid Amide

13. -carboxyl group -carbon side chain -amino group

14. Amino Acid Titration Below Isoelectric pH Net Charge + Above Isoelectric pH Net Charge – Isoelectric pH Net Charge 0

15. Isoelectric pH = 6.0 Titration of Glycine

16. Titration of Glutamic Acid Isoelectric pH = 3.2

17. Titration of Histidine Isoelectric pH = 7.6

18. Electrophoresis of Amino Acid Mixture at pH 6 Alanine, Arginine, Aspartic Acid At pH 6 Alanine (pI = 6) Net charge = 0 Arginine (pI = 10.8) Net charge is + Net charge is – Aspartic Acid (pI = 2.8)

19. Paper Chromatography of Amino Acids Asp Gly Lys Leu Phe Tyr polar amino acids nonpolar amino acids

20. Impact of changes in amino acids Biologically Active Peptides Vasopressin - Stimulates water reabsorption in the kidney Oxytocin - Stimulates lactation and uterine contraction

21. Levels of Protein Structure

22. Forces Involved in Protein Structure

23. Primary Structure of Insulin

24. Primary Structure of Lysozyme

25. Secondary Structure -Helix

26. Secondary Structure -Structure

27. Collagen (triple helix)

28. Elastin Structure

29. - helix Myoglobin: Secondary and Tertiary Structure - helix

30. Surface View Cross-Section Heme Group Myoglobin

31. Lysozyme: Secondary and Tertiary Structure - helix - structure

32. Active Site Lysozyme: Tertiary Structure

33. Hemoglobin: Quaternary Structure Heme Group

34. Sickle-cell Hemoglobin valine-valine interaction

35. Electrophoresis of Hemoglobin A, Sickle-Cell Hemoglobin, and Hemoglobin C Hemoglobin S Glu to Val at Position 6 on the Beta Chain Hemoglobin C Glu to Lys at Position 6 on the Beta Chain

36. Denaturation involves • The disruption of bonds in the secondary, tertiary and quaternary protein structures. • Heat and organic compoundsthat break apart H bonds and disrupt hydrophobic interactions. • Acids and basesthatbreak H bonds between polar R groups and disrupt ionic bonds. • Heavy metal ionsthatreact with S-S bonds to form solids. • Agitationsuch as whipping that stretches peptide chains until bonds break. Protein Denaturation

37. Use of 70% ethanol or isopropyl alcohol as a disinfectant • Use of silver nitrate solution in eyes of newborns to prevent gonorrhea infection Applications of Denaturation • Use of eggs or milk as antidote for heavy metal poisoning • Use of tannic acid in burn ointment to coagulate proteins at burn site • Use of high temperature to sterilize items

38. Denaturation and Renaturation of Ribonuclease