Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Protein structure & function

882 views

Published on

STRUCTURE & FUNCTION OF PROTEIN

Published in: Health & Medicine

Protein structure & function

  1. 1. Protein Structure and Function
  2. 2. Shape = Amino Acid Sequence Proteins are made of 20 amino acids linked by peptide bonds Polypeptide backbone is the repeating sequence of the N-C-C-N-C-C… in the peptide bond The side chain or R group is not part of the backbone or the peptide bond
  3. 3. Polypeptide Backbone
  4. 4. Amino Acids NOTE: You need to know this table Hydrophilic Hydrophobic
  5. 5. Protein Folding The peptide bond allows for rotation around it and therefore the protein can fold and orient the R groups in favorable positions Weak non-covalent interactions will hold the protein in its functional shape – these are weak and will take many to hold the shape
  6. 6. Globular Proteins The side chains will help determine the conformation in an aqueous solution
  7. 7. Hydrogen Bonds in Proteins H-bonds form between 1) atoms involved in the peptide bond; 2) peptide bond atoms and R groups; 3) R groups
  8. 8. Protein Folding Proteins shape is determined by the sequence of the amino acids The final shape is called the conformation and has the lowest free energy possible Denaturation is the process of unfolding the protein Can be down with heat, pH or chemical compounds In the chemical compound, can remove and have the protein renature or refold
  9. 9. Protein Folding 2 regular folding patterns have been identified – formed between the bonds of the peptide backbone α-helix – protein turns like a spiral – fibrous proteins (hair, nails, horns) β-sheet – protein folds back on itself as in a ribbon –globular protein
  10. 10. β Sheets Core of many proteins is the β sheet Form rigid structures with the H-bond Can be of 2 types Anti-parallel – run in an opposite direction of its neighbor (A) Parallel – run in the same direction with longer looping sections between them (B)
  11. 11. α Helix Formed by a H-bond between every 4th peptide bond – C=O to N-H Usually in proteins that span a membrane The α helix can either coil to the right or the left Can also coil around each other – coiled-coil shape – a framework for structural proteins such as nails and skin
  12. 12. Levels of Organization PrimaryPrimary structure Amino acid sequence of the protein SecondarySecondary structure H bonds in the peptide chain backbone  α-helix and β-sheets TertiaryTertiary structure Non-covalent interactions between the R groups within the protein QuanternaryQuanternary structure Interaction between 2 polypeptide chains
  13. 13. Protein Structure
  14. 14. Domains A domaindomain is a basic structural unit of a protein structure – distinct from those that make up the conformations Part of protein that can fold into a stable structure independently Different domains can impart different functions to proteins Proteins can have one to many domains depending on protein size
  15. 15. Domains
  16. 16. Useful Proteins There are thousands and thousands of different combinations of amino acids that can make up proteins and that would increase if each one had multiple shapes Proteins usually have only one useful conformation because otherwise it would not be efficient use of the energy available to the system Natural selection has eliminated proteins that do not perform a specific function in the cell
  17. 17. Protein Families Have similarities in amino acid sequence and 3-D structure Have similar functions such as breakdown proteins but do it differently
  18. 18. Proteins – Multiple Peptides Non-covalent bonds can form interactions between individual polypeptide chains Binding site – where proteins interact with one another Subunit – each polypeptide chain of large protein Dimer – protein made of 2 subunits  Can be same subunit or different subunits
  19. 19. Single Subunit Proteins
  20. 20. Different Subunit Proteins Hemoglobin 2 α globin subunits 2 β globin subunits

×