7_27 Lecture 3 Proteins 3.txt
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- author "Joshua Ellis"
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- fileName "7/27 Lecture 3 Proteins 3"
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- 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.
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.
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
Define Oligomer, dimer, and trimer.
Oligomer is a protein complex with multiple subunits.
- Dimer is two subunits
- Trimer is three
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)
What is Phosphofructokinase? Describe.
Homotetramer enzyme with four catalytic sites and 4 inner regulatory allosteric binding sites. (inhibited by ATP)
KEY CONTROL POINT FOR GLYCOLYSIS
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
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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