Proteins PDF

Proteins MC 101 – LECTURE PROPER 1. Enumerate the function of proteins. 2. Define and describe the properties of amino acids. 3. Describe and illustrate the formation of peptide bonds. 4. Describe the properties of proteins 5. Explain the levels of protein structure. 6. Discuss protein...

Proteins MC 101 – LECTURE PROPER 1. Enumerate the function of proteins. 2. Define and describe the properties of amino acids. 3. Describe and illustrate the formation of peptide bonds. 4. Describe the properties of proteins 5. Explain the levels of protein structure. 6. Discuss protein denaturation and its role. LEARNING OBJECTIVES PROTEINS ❑Proteins are large, complex molecules that serve several essential functions throughout the body. They do the majority of work in cells and are necessary for the construction, function, and control of the tissues and organs of the body. ❑Proteins are composed of tens of thousands or hundreds of thousands of smaller components called amino acids that are linked together in lengthy chains. Twenty distinct kinds of amino acids may be combined to form a protein. The sequence of amino acids defines the unique three- dimensional structure and function of each protein. Combinations of three DNA building units (nucleotides) define the genetic sequence of amino acids. ANTIBODY ENZYMES MESSENGER STRUCTURAL COMPONENT TRANSPORT/STORAGE EXAMPLES OF PROTEIN FUNCTIONS ANTIBODY Antibodies bind to specific foreign particles, such as viruses and bacteria, to help protect the body. Example: Immunoglobulin G (IgG) ENZYME Enzymes carry out almost all of the thousands of chemical reactions that take place in cells. They also assist with the formation of new molecules by reading the genetic information stored in DNA. Example: Phenylalanine hydroxylase MESSENGER Messenger proteins, such as some types of hormones, transmit signals to coordinate biological processes between different cells, tissues, and organs. Example: Growth hormone STRUCTURAL SUPPORT These proteins provide structure and support for cells. On a larger scale, they also allow the body to move. Example: Actin TRANSPORT/STORAGE These proteins bind and carry atoms and small molecules within cells and throughout the body. Example: Ferritin AMINO ACIDS Amino acids Are relatively simple molecules containing both an amine group and an acid group. (amino group and carboxyl group) Properties of Amino acid: They can join to form protein. They all have both an acid and a base. They all have variations in what part of the structure is protonated, depending on the solution’s pH and the rest of the molecule structure. They all, except glycine, have a chiral nature (4 different groups attached to the same carbon), influencing the reactions that the compound undergoes. Amino acids are positive and negative: the Zwitterion formation A zwitterion is a molecule with a net neutral charge that has positive and negative charged functional groups. The net charge of zwitterion as a whole is zero (0). Protonated? At a pH below the pKa for each functional group on the amino acid, the functional group is protonated. At a pH above the pKa for the functional group it is deprotonated. If the pH equals the pKa, the functional group is 50% protonated and 50% deprotonated. Carboxyl and amino groups are sensitive to pH. pH determines if they take up a H+ (protonation) or Lose a H+ (deprotonation) AMINO ACIDS Divided into 4 subgroups based on the nature of their side chain (groups attached to the a- carbon) and the general behavior of the amino acid: Nonpolar (hydrophobic) and uncharged Polar (hydrophilic) and uncharged Acidic (polar and charged) Basic (polar and uncharged) Nonpolar Alanine Glycine Isoleucine Methionine Phenylalanine Proline Tryptophan Valine Polar Asparagine Cysteine Glutamine Serine Threonine Tyrosine Acidic Aspartic acid Glutamic acid Basic Arginine Histidine Lysine Peptide bonds This type of bond is used in the synthesis of proteins. The interaction of two amino acids at the body’s pH results in the formation of a peptide bond. Two residues react to expel a water molecule, the same dehydration reaction, reverse of this is condensation reaction (hydrolysis). The resultant amide group is peptide bond. The presence of 2 amino acid residues means the product is a dipeptide. Peptide bond is a flat (planar) structure. Oxytocin and vasopressin are pituitary neuropeptides that have been shown to affect social processes in mammals. There is growing interest in these molecules and their receptors as potential precipitants of, and/or treatments for, social deficits in neurodevelopmental disorders, including autism spectrum disorder. Four levels of structure  Levels Primary, secondary, tertiary, and Quaternary Primary is the most fundamental level of all proteins. Quaternary is the most specific level that only some proteins have. Factors that may destroy the secondary, tertiary, and quaternary structures of protein: Heat, Changes in pH, reducing agents that can break linkages (disulfide linkages) Protein denaturation Protein denaturation Both the secondary and tertiary structures of proteins may be disrupted and destroyed during denaturation. Since denaturation reactions are insufficient to break peptide bonds, the fundamental structure (amino acid sequence) stays unchanged during a denaturation procedure. The process of denaturation destroys the typical alpha-helix and beta sheets of a protein, uncoiling it into a disordered form. The bonding interactions responsible for the secondary structure (hydrogen binds to amides) and tertiary structure are disturbed during denaturation. There are four kinds of bonding interactions between "side chains" in tertiary structure that are susceptible to disruption: hydrogen bonding, salt bridges, disulfide bonds, and non-polar hydrophobic contacts. Consequently, several chemicals and circumstances may induce denaturation. Protein precipitation or coagulation is the most frequent occurrence during the denaturation process. THANK YOU REFERENCES: M O O R E , T. ( 2 0 2 2 ). B I O C H E M I S T R Y F O R D U M M I E S ( 3 RD E D I T I O N ). W I L E Y P U B L I S H I N G , I N C. F E R R I E R , D. ( 2 0 1 8 ). L I P P I N C O T T I L L U S T R A T E D R E V I E W : B I O C H E M I S T R Y ( 7 T H E D I T I O N ). W O LT E R S K L U W E R Activity Instructor will assign partners. 1 amino acid will be assigned. Present the structure, Identify the subgroup, its use or function to human or daily lives. 50 points – 25% Presentation and explanation and 25% Supporting materials (PPT/Pics/Videos, etc) Each team will be given 4 mins (maximum) time to Present. Consuming the allotted time be given a deduction. Presentation will be on Thursday – 4PM – 6PM