B2W9 Flashcards
(35 cards)
What limits polypeptide folding?
- Rigid peptide bond
- Secondary structures
N side rotation angle
Phi
CO side rotation angle
Psi
Top left hand corner of ramachandran plot
Beta strands
Bottom left hand corner of ramachandran plot
Right-handed alpha-helix
(a) gives rise to several regular features called (b)
(a) hydrogen bonds (b) secondary struccture
Phi angle in alpha-helix
-57
Psi angle in alpha-helix
-47
How many residues per turn of alpha-helix?
3.6
Alpha-helix twists clockwise/anti-clockwise?
Clockwise
Peptide bonds are (a) and (b) in alpha-helix
(a) trans (b) planar
CO of each residue is H-bonded to NH of…
The 4th residue
Arrangement of groups of helices in membranes
Polar faces to the centre and non-polar faces towards the bilayer
alpha-helices can wind around each other to form…
‘coiled coils’ that are extremely stable
Coiled coils are found in (a) such as (b), (c)
(a) fibrous structural proteins (b) keratin (b) myosin
Function of ferritin
Store iron
Function of transferrin
Transport iron
How many irons does each transferrin molecule bind to?
2
Transferrin is delivered to tissues having…
Transferrin receptor 1 (TfR1)
Binding site of Transferrin has (a) with (b) and (c), H bonded to an (d)
(a) amino acids (b) electronegative atoms (c) bidentate carbonate (d) arginine side chain and the N terminus
alpha-helix breakers example
Glycine and proline
Why is glycine found in loops
Too flexible
Why is proline found in loops and turns
It is cyclic, therefore has restricted rotation and fixed phi angle
Direction of chains in parallel beta sheet
Same direction
