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19 Cards in this Set
- Front
- Back
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Where does a peptide bond form? |
Between 2 AAs, from the alpha carboxyl group of one to the alpha amino of the next |
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What is the geometry of the peptide bond? |
Planar |
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What is Phi? |
An angle formed between the amino nitrogen and the alpha carbon, a degree of rotation is allowed here |
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What is psi? |
The freedom of meovement of the angle between the alpha carbon and the carboxyl carbon |
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What influences the creation of different phi and psi angles? |
Steric hinderance, and the weak forces interacting. Depending on R groups, secondary structures may form, or certain angles are impossible because of interactions or bulky groups |
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Define an alpha helix |
The alpha helix is a spiral structure along a central axis. The backbone of the peptide structure wraps around this axis, and H bonding happens between the O of the carboxyl group of amino acid N and the amino group of amino acid N+4. So there is an H bond every 4 AAs in the structure, which stabilizes it.
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T/F R groups on an alpha helix face inward |
FALSE they face outward |
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Are most alpha helixes right or left handed? |
Right handed |
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what is the average length of an alpha helix? |
12 AAs or 3 turns |
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What is a beta sheet? |
The primary sequence of the beta strand moves in and out in a zig zag, and the R groups alternate facing up or down. Individual beta strands will align side-by-side to form beta sheets |
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___________________ bonding occurs between adjacent strands |
Hydrogen bonding holds the beta strands together to form beta sheets. Potential to maximize H bonding interstrand |
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Beta sheets take two forms? |
Parallel, where each strand is oriented amino to carboxyl terminal ends (L-->R). Antiparallel: Alternating between amino to carboxyl, then carboxyl to amino, then back again. In parallel, 120 degree bond angles for the H bonds In antiparallel, the bond angle for the H bonds is 180 degrees |
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What is a beta turn? |
Allows the structure to turn and fold back in another direction. Four amino acids, two main types Hydrogen bonding happens between the carboxyl oxygen of the first amino acid and the amino hydrogen of the 4th amino acid |
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What is a type I beta turn |
Proline is at teh second position |
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What is a type II beta turn? |
Glycine at the third position |
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Name 3 examples of super-secondary structures |
Beta barrel, alpha-alpha corner beta-alpha-beta loop |
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What is the tertiary structure? |
The combination of secondary structures to form regional structures. |
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What is quaternary structure? |
More than one peptide makes up the protein, and the multiple subunits are called oligomers. |
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What is Creutzfeld-Jacob disease? |
CJD is a prion disease, part of the transmissible spongiform encephalitis group. Neurodegenarative, affecting astrocytes or neuroglial cells of the brain Idea is that a native conformation change induces other native conformation changes in victim's tissues. So the abnormal, though rare, induces other abnormalities. |
