C12 Lecture 4

  1. Primary structure
    Protein's amino acid sequence
  2. Secondary structure
    Local spatial arrangement of a polypeptide's backbone atoms
  3. Does secondary structure consider side chains of a polypeptide?
  4. Tertiary structure
    3D structure of the entire chain
  5. Quaternary structure
    Spatial arrangement of different polypeptides in a protein
  6. Do all proteins have quaternary structure?

    Some proteins are functional alone in their tertiary form.
  7. How many amino acids in human Hgb α and β strands?

    How is this relevant to Hgb separation by SDS-Page?
    α: 142 a.a.

    β: 147 a.a.

    The chains are difficult to separate by weight (SDS-Page)
  8. 3D Hgb structure (1-4o)
    • 1o: KAHGKKVLGA (62-71)
    • 2o: alpha helix
    • 3o: One complete protein chain (beta chain of Hgb)
    • 4o: Four separate chains of Hgb assembled into an oligomeric protein
  9. Space filling model
    • Sphere = atom
    • Shows the surface exposed to solvent and ligands
  10. Ball and stick model
    Excellent for bonding arrangement
  11. Backbone model
    Excludes sidechains

    Shows general course of polypeptide chains
  12. Cartoon ribbon diagram
    • Most common
    • Easy to visualize 3D shape
    • Can see interior
    • Can see folds and patterns
    • Can add ball and stick portions
  13. How are proteins represented in a ribbon diagram
    alpha helices: coils/thick tubes

    beta strand: arrows

    lines or thin tubes: random coils
Card Set
C12 Lecture 4
C12 Lecture 4