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25 Cards in this Set
- Front
- Back
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What is necessary for disulfide bonds?
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cysteines close to each other in space
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Does oxidation or reduction produce disulfide bonds?
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oxidation
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What does beta mercaptoethanol do?
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reduces protein by breaking all disulfide linkages
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What happens after ribonuclease A is treated with excess beta mercaptoethanol? |
still functions but is much less stable
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What is urea? |
a chaotropic agent
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What does urea do? |
denatures by throwing out the hydrophobic effect
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What is the effect of urea on disulfide bonds? |
Since the protein is denatured, cysteines find each other randomly and not all the linkages are native.
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What are three conclusions about protein folding that can be drawn from the Anfinsen experiments?
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driven by primary structure rapid precedes covalent modifications |
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What are four examples of covalent modifications?
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disulfide bond formation glycosylation acetylation hydroxylation |
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What do incorrectly exposed hydrophobic residues lead to?
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protein aggregates
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What are three ways to avoid local minima? |
molecular chaperones protein-disulfide isomerase (PDI) peptidyl prolyl cis-trans isomerase (PPI) |
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What are heat-shock proteins?
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molecular chaperones
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inhibit or reverse formation of improperly folded proteins |
molecular chaperones
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shuffles disulfides in a protein until a stable native disulfide is formed |
protein-disulfide isomerase (PDI)
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What does PDI stand for? |
protein-disulfide isomerase
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catalyzes the interconversion of the cis and trans conformations of proline residue |
peptidyl prolyl cis-trans isomerase (PPI)
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look like two stacked tires, enable unfolded polypeptides to go inside and fold without interference |
molecular chaperones
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What are three examples of protein-folding diseases? |
Alzheimer's Huntington's Mad Cow |
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toxic beta-like structure that any aggregating proteins can adopt
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amyloid
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What is PRP essential in? |
developing memories
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How does PRP exist? |
in two stable conformations, one of which can aggregate
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infectious protein particles |
prion
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What are the main driving forces that lead to proper folding of the protein in the Anfinsen experiment? |
hydrophobic interactions and release of solvating water
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What occurs during protein denaturation?
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increase of disorder and fluctuating conformations
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Changes in what level of structure are responsible for creating amyloid fibers? |
secondary
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