7_27 Lecture 3 Proteins 3.txt

    • author "Joshua Ellis"
    • tags "HUCM"
    • description ""
    • fileName "7/27 Lecture 3 Proteins 3"
    • freezingBlueDBID -1.0
    • Myoglobin vs Hemoglobin
    • Hemoglobin transport oxygen in the blood, myoglobin stores it in the muscle.
    • Their proteins both contain a GLOBIN FOLD, which has 8 alpha helices to form the unique structure. It has a hydrophobic pocket. Globin is also in lysozyme.
  1. What is a TIM barrel fold?
    Triosephosphate isomerase (TIM) and other enzymes have this fold.

    It is an elaborate barrel structure that contains alternating segments of alpha helices and Beta strands.
  2. What is a Beta Barrel structure
    Retinol (vitamin A) is a hydrophobic molecule in the core of apleated up and down series of anti-parallel Beta strands
  3. Define Oligomer, dimer, and trimer.
    Oligomer is a protein complex with multiple subunits.

    • Dimer is two subunits
    • Trimer is three
  4. Heterotetramer vs homotetramer. What is an Isoform?
    Homo: 4 protein complex with all the same subunits. (ie: hemoglobin)

    Hetero: 1 or more is different in the 4 protein complex.

    • Isomer is something that can exist in different combinations of Homotetraer and heterotetramer. ie: lactate dehydrogenase (LDH)
    • ie: (myoglobin-- hemoglobin)
  5. What is Phosphofructokinase? Describe.
    Homotetramer enzyme with four catalytic sites and 4 inner regulatory allosteric binding sites. (inhibited by ATP)

  6. What is Aspartate Transcarbamoylase (ATCase)
    Allosteric enzyme that catalyzes pyrimidine nucleotide synthesis.

    Contains 2 catalytic trimers and 3 regulatory dimers

    Inhibited by CTP. Activated by ATP
  7. What are some advantages of being protein complex vs just a single protein
    regulation through COOPERATIVE EFFECTS!

    • channeling of substrates is huge! --- channels between different functional sites = multienzyme comlexes --- EFFICIENT
    • products of one reaction can be passed on to other parts of protein.
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7_27 Lecture 3 Proteins 3.txt