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21 Cards in this Set
- Front
- Back
Unique property of the protein RNAase |
If you denature it, it will refold and become active again. It has 8 cystines that make 4 disulfide bonds. Was also the first major experiment for protein folding. |
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The experiment with RNAase used discovered what? |
That the native conformation of a protein is the most thermodynamically stable.
Proteins follow unique paths to get to native state. Primary structure alone has the info for proper folding. |
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Enthalpy |
delta H. measure of bond formation (-) or bond breaking (+) |
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Entropy |
Delta S. A measure of increasing chaos (+) or decreasing chaos (-) |
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Summary of Levintal's Paradox |
Proteins must have a process to their folding since to try every combination would take a period of time longer than the age of the universe. |
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Globular protein folding is driven by what? And how do we know? |
they are Entropy driven: the increased randomness of water We know this because of the Heat Capacity (Cp) When denatured, Cp increases, when folded, Cp decreases. |
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How do alcohols denature proteins? |
by making H-bonds with the protein and disrupting the structure. |
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Fibrous protein folding is driven by what? and why? |
They are Enthalpy driven. They are often made primarily of polar aa's that like to associate with water. |
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What is the average free energy of folding? |
-5 to -15 kcal/mole. |
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What are the 3 main lessons of protein folding? |
1. Evolution favors flexibility 2. Native proteins are on the borderline of denaturation 3. Misfolding is common. |
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What are the 3 main functions of molecular chaperones? |
1. Protect new proteins from interference from other proteins 2. To accelerate slow steps 3. To ensure correct folding. |
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Chaperone proteins are typically classified as what? And what does that mean? |
"Heat-shock proteins" Their levels go up under stress and their function increases. |
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What is a prime example of a heat shock protein? And what is it's mammalian equivalent? |
GroES-GroEL of bacteria. TRiC is the mammalian equivalent. |
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Besides GroEL-GroES, what is the other common heat shock protein and what does it do? |
Hsp 70; it assists folding the hydrophobic portion by binding to and protecting them. |
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True/False: There is no energy required for the GroEL-GroEs complex. |
False. Energy is required to take on and off the cap. |
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What is the purpose of PDI? and what does it stand for? |
PDI: protein disulphide isomerase. It breaks disulfide bonds, allowing incorrect ones to hopefully reform correctly. |
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What does PPI stand for and what does it do? |
PPI: Peptidyl prolyl isomerase. It catalyzes cis-trans isomerization of X-P bonds. It changes the angle of proline bonds. |
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Summarize the folding funnel |
As proteins fold, they move from a high energy state at the top of the funnel, to the lowest free energy state as the correctly folded protein. There are multiple pathways down. |
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Name two diseases caused by improperly folded/made proteins. |
Alzheimer's disease Creutzfeldt-Jacob disease (mad cow) Cystic Fibrosis. |
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Briefly describe Alzheimer's disease. |
During the formation of the amyloid protein, portions of the precursor protein must be chopped. If the wrong sections are cleaved first, the resulting pieces will join together and form a plaque that causes Alzheimer's. |
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Briefly describe prion diseases |
a prion in its natural alpha helix dominant state will occasionally denature and reform into a beta sheet conformation spontaneously. If this improper conformation is not dealt with, it will affect more of the properly folded prions to become misfolded. |