Keratin is a coiledcoil protein Answer the following questio

Keratin is a “coiled-coil” protein. Answer the following questions about keratin.

a)Keratin proteins have a “pseudorepeat” of how many residues?

b)At what positions are hydrophobic residues found in the pseudorepeat?

c)Why are there hydrophobic residues at those positions?

d)Polar residues are usually found at the remaining positions. Why?

e)Which of the following possible peptides is most likely to be a pseudorepeat? (pick only one)

D-Q-I-E-V-E-R

W-Q-E-Y-E-R-D

I-Q-E-V-E-R-D

f)What is wrong, or less good, about the other two possibilities?

A) 7- it is a heptad forms a hydrophobic core

B) it is present within the central 310 segment of molecule. In the pseudorepeats every first and fourth residues are hydrophobic

C) These hydrophobic residues helps to pack the protein into a longitudinal hydrophobic core by combining the two subunits and gives stability