1. Prepared by: Moises Von Rosauro R. De Gracia BSEd IV Physical Science Tarlac College of Agriculture

2. What is Protein? Proteins are the most versatile cell components Composed of C, H, O, N plus other elements such as S, I, Fe, P etc. Also, they are considered as necklaces of amino acids. 3. Classification of Proteins Based on Composition: Simple proteins composed of entirely amino acids only. Ex. Albumins and Globulin Conjugated Proteins simple proteins in union with other substances Nucleoprotein, Glycoprotein and Lipoprotein 4. Based on Axial Ratio: Axial ratio is the ratio of the length to the breadth. Globular proteins the polypeptide are so tightly folded into spherical or globular shapes. Ex. Insulin, plasma albumin, globulin, enzymes Fibrous proteins They are spiral and helical and are cross linked by disulfide and hydrogen bonds. Ex. Keratin, myosin, elastin, collagen 5. Amino Acids Proteins when hydrolyzed either by boiling with acids or through the action of enzymes, are broken down into their component amino acids. The amino acids are of the -form, that is the amine group (-NH2) is attached to the C atom next to the carboxyl group (-COOH). H N H C C CH3 OH O H H N+ H C C CH3 O- O HH Figure 1. Amino Acid at pH 7 6. 20 amino acids are commonly found in proteins, each identified by the variable side chain (R group) bonded to the alpha carbon. The amino acids are grouped by the properties of their side chains. (next slides) Amino acids are classified as having Non polar (hydrophobic) Polar (uncharged) Acidic Basic 7. Nonpolar Amino Acids Leucine (Leu, L) Proline (Pro, P) Alanine (Ala, A) Valine (Val, V) Polar Amino Acids Threonine (Thr, T) Serine (Ser, S) Aspargine (Asn, N) Glutamine (Gln, Q) Basic Lysine (Lys, K) Arginine (Arg, R) Acidic Amino Acids Aspartic Acid (Asp, D) Glutamic Acid (Glu, E) Methionine (Met, M) Tryptophan (Trp, W) Phenylalanine (Phe, F) Isoleucine (Ile, I) Glycine (Gly, G) Cysteine (Cys, C) Tyrosine (Tyr, Y) Histidine (His, H) 8. Nonpolar Amino Acid COO- H3N+ C H CH2 CH H3C CH3 Leucine (Leu, L) Proline (Pro, P) COO- H3N+ C H CH2 CH2 H2C COO- H3N+ C H CH3 Alanine (Ala, A) Valine (Val, V) COO- H3N+ C H CH CH3 CH3 9. Polar Amino Acid COO- H3N+ C H CH2 OHH CH3 Threonine (Thr, T) COO- H3N+ C H CH2 OH Serine (Ser, S) COO- H3N+ C H CH2 C Aspargine (Asn, N) O NH2 COO- H3N+ C H CH2 C Glutamine (Glu, Q) O NH2 CH2 10. Acidic Amino Acid COO- H3N+ C H CH2 COO- Aspartic Acid (Asp, D) COO- H3N+ C H CH2 COO- Glutamic Acid (Glu, E) CH2 COO- H3N+ C H CH2 S Methionine (Met, M) CH2 CH3 11. Acidic Amino Acid COO- H3N+ C H CH2 Phenylalanine (Phe, F) COO- H3N+ C H CH2 CH Tryptophan (Trp, W) C NH COO- H3N+ C H C H CH2 Isoleucine (Ile, I) CH3 H3C 12. Acidic Amino Acids COO- H3N+ C H H Glycine (Gly, G) COO- H3N+ C H CH2 Cysteine (Cys, C) SH COO- H3N+ C H CH2 Tyrosine (Tyr, Y) COO- H3N+ C H CH2 C NH CH H+N CH Histidne (His, H) 13. Basic Amino Acid COO- H3N+ C H CH2 Lysine (Lys, K) CH2 CH2 CH2 NH3 + COO- H3N+ C H CH2 Arginine (Arg, R) CH2 NH CH2 C H2 +N NH2 14. Biochemical Importance of AA Amino Acids Systematic name Importance Glycine Amino ethanoic acid Helps trigger the release of oxygen to the energy requiring cell-making process Important in the manufacture of hormones for strong immune system Alanine -amino propanoic acid Important AA as it is an energy source for the liver, muscles, and CNS Strengthens the immune system by producing antibodies Helps in the metabolism of sugars and organic acids 15. Valine -amino 3- methylbutanoic acid Essential AA Promotes mental vigor, muscle coordination and calm emotions Leucine -amino 4-methyl pentanoic acid Essential AA Provides necessary substances for energy production Stimulants to the upper brain and helps to be more alert Isoleucine -amino 3- methylpentanoic acid Essential AA Same functions as leucine 16. Phenylalanine -amino 3- phenylpropanoic acid Essential AA Used by the brain to produce norepinephrine, Reduces hunger pains Functions as antidepressant Helps improve memory Tyrosine -amino 3-(4- hydroxyphenyl)pro panoic acid Transmits nerve impulses to the brain; helps overcome depression; improves memory; increases mental alertness; promotes the healthy functioning of the endocrine glands Tryptophan -amino 3-indole propanoic acid Essential AA A natural relaxant, helps alleviate insomia by inducing normal sleep Reduces anxiety and depression Helps in the treatment of migraines and headaches Helps stabilize the immune system Helps reduce risk of artery and heart spasms Works with lysine in reducing cholesterol levels 17. Methionine -amino 4- methyl thiol butanoic acid Essential AA Principal supplier of sulfur which prevents disorder of the hair, skin and nails Helps lower cholesterol levels by increasing the livers production of lecithin A natural chelating agent for heavy metals Regulates the formation of ammonia and creates ammonia-free urine which reduces bladder irritation Influences hair follicles and promotes hair growth 18. Cysteine 2-amino 3- mercaptopropanoic acid Functions as an antioxidant and is a powerful aid to the body in protecting against radiation and pollution Helps slow down the aging process, deactivate free radicals, neutralizes toxins Aids in protein synthesis and promotes cellular repair Necessary for skin formation, in the recovery from burns and surgical operations Serine 2-amino 3 hydroxy propanoic acid A storage source of glucose by the liver and muscles Helps strengthen immune system by providing antibodies Synthesizes fatty acid sheath around nerve fibers Threonine 2-amino 3 hydroxy butanoic acid Essential AA Important constituent of collagen, Assists metabolism and assimilation Helps the digestive and intestinal tracts functions normally Helps prevents fat build-up in the liver 19. Histidine -amino 3 (1H- imidazol-4-yl) propanoic acid Essential AA Found abundantly in hemoglobin Used in the treatment of rheumatoid arthritis, allergic diseases, ulcers, anemia Lysine 2,6 diamino hexanoic acid Essential AA Insures adequate absorption of calcium Helps form collagen (which makes up bone and cartilages) Aids in the production of antibodies, hormones and enzymes Arginine -amino 5- guanidino pentanoic acid Helps improve immune responses to bacteria, viruses and tumor cells Promotes wound healing and regeneration of the liver Causes the release of growth hormones Crucial for optimal muscle growth and tissue repair 20. Aspartic Acid -amino butanedioic acid Most easily used as energy source Aids in the expulsion of toxic ammonia from the body Located most closely to the TCA cycle, the site of energy production Found in increased levels in people with epilepsy and in decreased amounts in some cases of depression Glutamic acid -amino pentanedioic acid Considered to be natures brain food by improving mental capacities Helps speed the healing of ulcers; gives a lift from fatigue Helps control alcoholism, schizophrenia and the craving of sugar, Parkinsons disease, mental retardation, and muscular dystrophy Asparagine -amino 3 carbamoyl propanoic acid Found in the surfaces of proteins where they can interact with water molecules 21. Glutamine -amino 4 carbamoyl butanoic acid Found in the surfaces of proteins where they can interact with water molecules The polar amide groups can also form hydrogen bonds with atoms in the side chains of other polar amino acids Proline Pyrrolidine-2- carboxylic acid Non-essential AA Important for the proper functioning of joints and tendons Helps maintain and strengthen heart muscles Helps repair processes after cell injury or for any type of wound healing 22. Peptide Bonds Amino acids combine chemically with one another by a condensation reaction that bonds the carboxyl carbon of one molecule to the amino nitrogen of another. The covalent carbon to nitrogen bond linking two amino acid is peptide bond. Dipeptide combination of two amino acid Polypeptide longer chain of amino acid 23. H C H N H H C O OH R group R group Carboxyl Group Amino Group H CH3 C H N H C O OH CH3 C H N H C O OH H C H N H H C O Glycine, Gly Alanine, Ala Glycylalanine 24. Proteins Level of Organization Primary Structure the amino acid sequence Secondary Structure results from H bonding involving backbone Tertiary Structure depends on the interaction among sides Quaternary structure results from interaction among polypeptides 25. Primary Structure Primary structure describes the unique order in which amino acids are linked together to form a protein. The sequence of amino acids, joined by peptide bonds is the primary structure of polypeptide chain. Primary structure is always represented in a simple linear, beads-on-a- string form. H3N COO- 26. Secondary Structure refers to the coiling or folding of a polypeptide chain that gives the protein its 3-D shape. Secondary structure results from hydrogen bonding involving the backbone. There are two common types of secondary structure. helix pleated sheet 27. helix It is a region where a polypeptide chain forms a uniform helical coil. The helical structure is determined and maintained by the formation of H-bond between the backbone of AA in successive turns of the spiral coil. C C N C C N C C N C C N C C N O H 28. pleated sheet Beta pleated sheet is a regular, folded, sheet like type of secondary protein structure, resulting from H- bonding between two different polypeptide chains or two region of the same polypeptide chain. 29. Tertiary Structure Tertiary structure is the overall three-dimensional shape of a polypeptide that is determined interaction involving the amino acid side chains. The four main factor involve in tertiary structure Hydrogen bond Ionic bond Hydrophobic interaction Covalent bonds 30. Four main factors Hydrogen bond forms between the R groups of certain Amino acid subunits. An ionic bond can occur between R group with a unit of positive charge and one with a unit of negative charge. Hydrophobic interactions results from the tendency of nonpolar R groups to be excluded by the surrounding H2O. Formation of covalent bond called disulfide bridges. 31. Quaternary Structure Quaternary structure results from interaction among polypeptides. The same types of interaction that produces secondary and tertiary structure also contributes to quaternary structure. refers to the structure of a protein macromolecule formed by interactions between multiple polypeptide chains. Each polypeptide chain is referred to as a subunit. Proteins with quaternary structure may consist of more than one of the same type of protein subunit. They may also be composed of different subunits. 32. AA sequence determines its conformation Christian B. Anfinsen (1972) Awarded Nobel Prize in Chemistry for his study in protein folding. Work under in vitro (outside a living cell) Due to different conditions the in vitro and in vivo, scientist observed a molecular chaperones. Molecular Chaperones mediates the folding of other protein molecules. They are thought to make the folding process more orderly and efficient. Domain is the structural and functional region of protein 33. General Function of Protein Proteins are very important molecules in our cells. They are involved in virtually all cell functions. Each protein within the body has a specific function. Some proteins are involved in structural support, while others are involved in bodily movement, or in defense against germs. Proteins vary in structure as well as function. 34. Protein as. Antibodies Contractile protein Enzyme Hormone Structural Protein Storage Protein Transport Protein Energy 35. Antibodies Antibodies - are specialized proteins involved in defending the body from antigens (foreign invaders). They can travel through the blood stream and are utilized by the immune system to identify and defend against bacteria, viruses, and other foreign intruders. One way antibodies counteract antigens is by immobilizing them so that they can be destroyed by white blood cells. 36. Contractile Protein Contractile Proteins - are responsible for movement. Examples include actin and myosin. These proteins are involved in muscle contraction and movement. Actin and myosin are two specialized types of filament protein present in your muscle. When stimulated by a signal from the central nervous system, these two proteins act in unison to shorten in length, causing your muscle to contract. 37. Enzymes Enzymes - are proteins that facilitate biochemical reactions. They are often referred to as catalysts because they speed up chemical reactions. Examples include the enzymes lactase and pepsin. Lactase breaks down the sugar lactose found in milk. Pepsin is a digestive enzyme that works in the stomach to break down proteins in food. 38. Hormone Hormonal Proteins - are messenger proteins which help to coordinate certain bodily activities. Examples include insulin, oxytocin, and somatotropin. Insulin regulates glucose metabolism by controlling the blood-sugar concentration. Oxytocin stimulates contractions in females during childbirth. Somatotropin is a growth hormone that stimulates protein production in muscle cells. 39. Structural Protein Structural Proteins - are fibrous and stringy and provide support. Examples include keratin, collagen, and elastin. Keratins strengthen protective coverings such as hair, quills, feathers, horns, and beaks. Collagens and elastin provide support for connective tissues such as tendons and ligaments. 40. Storage Protein Storage Proteins - store amino acids. Examples include ovalbumin and casein. Ovalbumin is found in egg whites and casein is a milk-based protein. 41. Transport Protein Transport Proteins - are carrier proteins which move molecules from one place to another around the body. Examples include hemoglobin and cytochromes. Hemoglobin transports oxygen through the blood. Cytochromes operate in the electron transport chain as electron carrier proteins. 42. Protein in Cell Structure Microtubules play a major role in organizing the cytoplasm and in the distribution of organelles. They also form the mitotic spindle during cell division. Actin filaments are involved in various forms of cell movement, including cell locomotion, contraction of muscle cells, and cell division Intermediate filaments are strong fibers that serve as architectural supports inside cells. 43. Proteins in Plasma Membrane Transporters carry a molecule (such as glucose) from one side of the plasma membrane to the other. Receptors can bind an extracellular molecule (triangle), and this activates an intracellular process. Enzymes in the membrane can do the same thing they do in the cytoplasm of a cell: transform a molecule into another form. Anchor proteins can physically link intracellular structures with extracellular structures. 44. Summary Protein are complex macromolecule made up of simpler subunits called amino acids, joined by peptide bonds. When two amino acid combine, they form a dipeptide Longer chain of amino acid is a polypeptide. All amino acid contain an amino group and a carboxyl group. 45. Primary structure of protein is the linear sequence of amino acid Secondary structure is a regular conformation, such as an alpha helix and beta pleated sheet; it is due to H- bond between the elements of the backbone Tertiary Structure is the overall shape of the polypeptide chain Quaternary structure is determined by the association of two or more polypeptide chain. 46. Thank you