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23 Cards in this Set
- Front
- Back
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What is an induced fit?
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When a ligand binds to a protein and the protein changes it's shape to better accommodate the ligand.
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What is the molecule acted on by an enzyme called?
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a substrate
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What is Heme composed of?
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Fe and porphyrin
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How are Ka and Kd related?
What do each stand for? |
Kd is 1/Ka
Ka = association constant Kd = dissociation constant |
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Are alpha hemoglobin, beta hemoglobin, and myoglobin similar in structure?
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Yes
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What is a cross-linked bond and what is a disulfide bond? Where can each be found?
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A cross linked bond, found in collagen, is a covalent-type interaction between lysine and a hydroxyl group. A disulfide bond, found in alpha-keratin, is a bond between cystine groups (disruption and recreation of this causes a perm).
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In hemoglobin, what is the R state and what is the T state? How does each affect binding of O2?
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R state is relaxed; fewer bonds holding the protein together. T state is tight; more bonds holding the protein together. R has a high affinity (there are more free electrons to attract O2) and T has a low affinity.
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What does allosteric mean?
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Pertaining to the regulation of enzyme activity.
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What is chlorophyll composed of?
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a porphyrin ring with a Mg atom.
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What is a B12 molecule made of?
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a porphyrin ring with a cobalt atom.
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How does myoglobin store O2 in the muscle so well?
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It has a very high affinity for O2.
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High affininty = low Kd value. Why?
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With a high affinity, ligands are bound very tightly and don't dissociate very readily.
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Why does CO bind so tightly to myoglobin?
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It binds straight on due to its SP orbital. O2 has an SP3 orbital pattern so it binds crookedly, and less tightly.
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Why is CO bound 20000 X's more tightly in myoblobin than O2 and only 200 X's more tightly in hemoglobin?
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There's a histadine group that prevents a good, straight-on bond.
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What is allosteric binding?
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One ligand bonding causes a conformational change at the binding site of another ligand.
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What is lung pH generally, and what is tissue pH?
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7.6 and 7.2, respectively.
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What factors can change affinity of O2 in hemoglobin?
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pH-
CO2- 2,3 BPG- is wedged in the middle of hemoglobin; keeps a more permanent R-state so more O2 comes off than normal. CO- Irreversibly binds to Fe |
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What is another name for a salt bridge?
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Ionic bond
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What are the three types of protein separation chromatography?
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Ion exchange, size exclusion, and affinity binding.
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Why does 2,3 BPG bind to the hole in hemoglobin?
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2,3 BPG has a negative charge and the hole of the heme is negative.
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Where would you most likely find someone with high amounts of 2,3 BPG?
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Living at a high elevation.
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In Cystic Fibrosis, what is the cause of the mutated channel?
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A deletion of phenylalanine at the 508 position.
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Where does 2,3 BPG come from?
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It is a product of glycolytic metabolism.
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