-
What is the secondary structure of a protein?
- The organization of primary structural features.
- Alpha helices and beta sheets
-
What is the tertiary structure of a protein?
Steric relationships of AA's that may be far apart in AA sequence
-
What is quaternary structure of a protein?
Mode of association between two or more polypeptide chains
-
How are the six atoms in an AA oriented?
Coplanar. This is due to resonance.
-
Does the alpha carbon in a peptide bond lie cis or trans to a C-N bond?
Trans
-
What is the vertical rise for each AA residue in an alpha helix?
- 1.5 angstroms.
- There are 3.6 resudes per turn.
- Each residue gives 100 degrees of separation.
-
What is an alpha helix stabalized by?
Hydrogen bonds between carboxyl and amino groups
-
What is a very common "open" motif that can have parallel or antiparallel configurations, and is stabilized by hydrogen bonding?
Beta sheet
-
What residues favor formation of alpha helix?
Met, Glu, Leu, Ala, Gln
-
Which residues favor formation of beta sheets?
Val, Ile, Phe, Tyr
-
In a membrane integral protein that forms a water pore, where would charged residues be found? Where would hydrophobic residues be found?
- Charged - in the center of the pore
- Hydrophobic - on the outside of the pore
-
How can water soluble enzymes be associated with membranes?
Post translational modifications with hydrophobic groups
-
Whis is a disulfide bridge?
- Oxidative cross binding of cysteine residues.
- Sulfhydryl groups giving up electrons (H) to bind to another sulfhydryl group that has lost an electron
-
Describe the residues of intrinsically unstructured proteins.
Many charged residues. Also very polar.
-
What does PDI do?
Catalyzes disulfide exchange reactions
-
What does PPI do?
Catalyzes interconversion of cis to trans configuration in peptide bonds. (Trans is normal)
-
What do molecular chaperones do?
Bind to hydrophobic portions of a protein and keep them from aggregating and folding.
-
What is a contiguous portion of a polypeptide chain that folds independently into 3d structures?
Domain
-
What does Cystic Fibrosis result from?
F508X mutation in CFTR. This results in improper folding of chloride transport protein.
|
|
