Card Set Information

2011-09-28 12:55:09
Protein Structures

Begin page 42
Show Answers:

  1. What is the result of a sequence of amino acids that has been disrupted; therefore causing an abnormal sequence?
    Abnormal sequence of amino acids specified for a particular protein results in misfolding of that protein, which in turn causes impairment of normal functioning.
  2. What are examples of secondary Structures of proteins and what type of bonds are used?
    • Alpha Helix
    • Beta Sheet

    Both are stabilized by extensive hydrogen bonding between the peptide bond carbonyl oxygens and amide hydrogens that make up the polypeptide backbone.

    Hydrogen bonding can also occur between two different chains
  3. What are the characteristics of the alpha helix?
    • - Possesses a "right hand turn"
    • - Each turn contains 3.6 amino acids
  4. What is the amino acid that interrupts the alpha helix and how?
    Proline produces a "kink" in the a-helix because it's structure is incompatible with the right hand spiral of the a-helix
  5. What is the characteristic feature of Beta Sheets
    They have a pleated appearance.
  6. What is the structure of globular proteins?

    What are the two different amino acids that must be in the structure?
    Nearly 1/3 of the amino acid residues are in turns or loops where the polypeptide chain reverses direction.

    The structure involves 4 amino acids, one of which must be proline or glycine.
  7. Serum albumin is what type of protein and what level of structure?
    Mostly alpha helices, tertiary structure
  8. Collagenase is what level of protein structure and what kind of protein?
    Mostly Beta strands, tertiary structure.
  9. Thymidylate synthase is what kind and level of protein structure?
    Mixed alpha helices and Beta strands, tertiary structure.
  10. What type of bonds stabilize tertiary structures?
    • Disulfide bonds
    • Hydrogen bonds
    • Ionic Bonds
  11. What determines the shape of secondary, tertiary functional protein?
    Interactions between the side chains of amino acids determines how a polypeptide chain folds into the intricate three-dimensional shape.
  12. Characteristics of protein Domains?
    Folding of peptide chains within a domain is INDEPENDENT of folding in other domains
  13. Bovine spongiform encephalopathy, Amyloidoses and Alzheimer disease are the result of what?
    Protein misfolding. For example, association of infected molecules change the folding from the intended to alpha helix to (misfolding) beta sheets.
  14. What are characteristics of a Quaternary Structure?
    Made by 2 or more polypeptide chains (subunits, or tertiary structures).

    • These subunits are interact by
    • Hydrogen bonds
    • Ionic bonds
    • Hydrophobic
  15. How do the subunits of a Quaternary structure interact?

    Examples of this level of structure

    Either cooperatively or independently

    • Ex: - human hemoglobin
    • - protein kinase
  16. What are conjugated proteins?
    These are proteins that contain permanently associated chemical components in addtion to amino acids
  17. What is the range in number of Amino Acids in the chart he presented of proteins with quaternary structure?
    Ranges from 972 to 5,628 amino acids
  18. What happens when proteins denature?
    Unfolding and disorganization of the proteins secondary and tertiary structures, which are not accompanied by hydrolysis of peptide bonds
  19. What are possible denaturing factors?
    • Heat
    • Strong acids or bases
    • Organic solvents
    • Detergents
    • Ions of heavy metals such as lead, mecury
  20. Why do denatured proteins precipitate out of solutions?
    Because they are often insoluble