1. Amino Acids, Peptides, and Proteins

2. Peptides and proteins are polymers of amino acids linked together by amide bonds

4. NameThree-letter abbreviationOne-letter symbol AlanineAlaA ArginineArgR AsparagineAsnN Aspartic acidAspD CysteineCysC Glutamic acidGluE GlutamineGlnQ GlycineGlyG HistidineHisH IsoleucineIleI LeucineLeuL LysineLysK MethionineMetM PhenylalaninePheF ProlineProP SerineSerS ThreonineThrT TryptophanTrpW TyrosineTyrY ValineValV

5. Aliphatic Side-Chain Amino Acids glycine alanine valine leucine isoleucine

6. Hydroxy-Containing Amino Acids serine threonine

7. Sulfur-Containing Amino Acids cysteinemethionine

8. Acidic Amino Acids aspartatic acidglutamic acid

9. Amides of Acidic Amino Acids asparagine glutamine

10. Basic Amino Acids lysinearginine

11. Benzene-Containing Amino Acids phenylalaninetyrosine

12. Heterocyclic Amino Acids proline histidine tryptophan

13. Configuration of Amino Acids

14. Acid–Base Properties of Amino Acids An amino acid can never exist as an uncharged compound

16. Formation of a Peptide Primary structure

17. Amides Features of a Peptide Bond; 1.Usually inert 2.Planar to allow delocalisation 3.Restricted Rotation about the amide bond 4.Rotation of Groups (R and R’) attached to the amide bond is relatively free ------------- Not acids or bases

18. Peptide Bond

19. Identification of end-groups Identification of amino-terminal: Sanger’s reaction CH R 1 NHC O CHNH 2 R 2 F NO 2 NO 2 CH R 1 NHC O CHNH R 2 NO 2 NO 2 hydr. amino acid + HOOCCHNH R 2 NO 2 NO 2 (DNP-amino acid)

20. Carboxypeptidase A catalyzes the hydrolysis of the C-terminal peptide

21. Biologically active oligopeptides: Mw. < 5000-10 000 No. Amino acid units < 40-80 1. Dipeptides : Carnosine:

22. 3. Tripeptides : - 4. Pentapeptides : Enkephalins: Leucine enkephalin (endorphins opiatelike effects) Glutathione: 2. Tripeptides:

23. 5. Nonapeptides : Oxytocin - Vasopressin Lactation Uterine control Decreases blood pressure Excretion of water Increases blood pressure

24. Bradykinin Dilation of blood vessels Reduction of blood pressure Pain producing agent 6. Other hormones : Corticotropin (ACTH): Insulin: 39 amino acids Corticotropin-like peptides (CLIP):18-39 amino acids 51 amino acids 7. Antibiotics-toxins : Phallotoxins Penicillins, Gramicidins

25. Insulin Isolation: 1921. (Banting, Best, Collip & Macleod) Structure: Sanger, 1953-55

26. Strategy for Making a Specific Peptide Bond

27. Secondary Structure of Proteins Describe the conformation of segments of the backbone chain of a peptide or protein Three factors determine the choice of secondary structure: the regional planarity about each peptide bond maximization of the number of peptide groups that engage in hydrogen bonding adequate separation between nearby R groups

28. The  -Helix Is Stabilized by Hydrogen Bonds Prolines are helix breakers

29. Two Types of  -Pleated Sheets

30. The tertiary structure is the three-dimensional arrangement of all the atoms in the protein

31.  -helix pleated sheet C-terminal N-terminal random structures Tertiary structure

32. Hexokinase undergoes a conformational change upon binding to a substrate red: before substrate-binding green: after substrate-binding

33. Most globular proteins have coil conformations

34. The stabilizing interactions include covalent bonds, hydrogen bonds, electrostatic attractions, and hydrophobic interactions The tertiary structure is defined by the primary structure Disulfide bonds are the only covalent bonds that can form when a protein folds Proteins that have more than one peptide chain are called oligomers

35. The disulfide bridge in proteins contributes to the overall shape of a protein

36. Quaternery Structure

37. Classes of proteins According to Composition Polypeptides Amino acids Conjugated proteins Amino acids + nonprotein group According to Solubility Fibrous proteines Keratins Collagenes Fibrin Myosins Globular proteines Albumins Globulins Enzymes Hemoglobin

38. TypeBiological Functions Enzymes Trypsin Ribonuclease Cleavage of specific peptide bonds Fragmentation of ribonucleic acids Transport proteins Hemoglobin Myoglobin Ceruloplasmin B1-lipoprotein Oxygen transport in blood Oxygen transport in muscle Copper ion transport in blood Lipid transport in blood Contractile proteins Myozin Tubullin Contractile system of skeletal muscle Microtubules in flagella and cilia Structural proteins Collagen Keratin Major component of tendons and cartilage Insoluble protein of hair

39. TypeBiological Functions Nutrient and storage proteins Ovalbumin Casein Major protein of egg white Major protein of milk Defense proteins Immunoglobulins Thrombin Recognition and protection against „foreign” molecules Blood-clotting Regulatory proteins Insulin Transcription factors Glucose metabolism Regulation of gene transcription

40. HormoneM r Number of amino acid residues Anterior pituitary Adrenocorticotropic hormone Luteinizing hormone Follicle stimulating hormone Prolactin Growth hormone 4700 28500 34000 21500 21000 39 200 191 Posterior pituitary Oxytocin Vasopressin 1070 9999 Thyroid gland Parathormone Calcitonin 9500 4500 84 32 Pancreas Insulin Glucagon 5500 3500 51 29

41. Protein Molecular mass Number of residues Number of polypeptide chains Insulin5 700512 Ribonuclease l12 6001241 Myoglobin16 9001531 Hemoglobin64 5005744 Serum albumin68 000~5501  -globulin 149 900~1 2504 Glycogen phosporylase190 0001 6422 Pyruvate dehydrogenase complex 4 600 000~36 50060 Coat proteins of tobacco mosaic virus 40 000 000~380 0002 130