Secondary Structure

Question 1

2o structure 1

Answer 1

Twisting or folding
2 types- alpha helix,beta sheets

Question 2

Alpha helix

Answer 2

Spiral structure
Rigid arrangement
Tightly packed,coiled structure, a.a towards outside from central axis
Hydrogen bonding-Bw H atom of Npeptide and O atom of C peptide, bond individually weak but collectively strong

All except 1st and last participate in H bonding
Each turn-3.6
Distance of alpha helix-0.54
Bw a.a spacing-0.15
Stable confirmation formed with lowest energy
Right hand more stable
Stable but some a.a district alpha helix
Eg. Proline, acids and bases

Question 3

Beta sheet

Answer 3

2 or more segments of fully extended peptide chain
H bonds
Polypeptide chains -either parallel or antiparallel

Separate Polypeptide or single peptide holding back onto itself

Question 4

3o structure

Answer 4

3D arrangement of protein
Hydrophobic to interior
Hydrophilic on the surface of the molecule.hence ensures stability

Question 5

Bonds of 3o structure

Answer 5

H bond
Disulphide bond
Ionic interaction and hydrophobic

Question 6

Domain

Answer 6

Structurally and functionally active units
Basic structure
In 200 a.a ,2or more domains exist