Question

(j)

A synthetic protein made only of Lys is called polylysine. Polylysine is a random coil at pH ≤ 11.0, while it forms an α-helix if the pH is raised to greater than 12. This is because at pH 12:

Group of answer choices

the high concentration of OH^- ions in solution reduces the electrostatic repulsion between the R groups.

the positive charges on the lysine residues stabilize the α-helix.

the negative charges on the lysine residues stabilize the α-helix

the lysine residues are uncharged which eliminates the electrostatic repulsion between the R groups.

the high pH eliminates the polarity across the α-helix.

(k)

Use the half reactions and reduction potentials provided below to calculate the ΔG°’ of:

Butyryl-CoA + NADP⁺ + H⁺⇋ Crotonyl-CoA + NADPH

NADP⁺ + H⁺ + 2e^-  → NADPH, E^0' = -0.324 volts

Crotonyl-CoA + H⁺ + 2e^-→ Butyryl-CoA, E^0' = -0.150 volts

Group of answer choices

ΔG°’ = -48 kJ/mol

ΔG°’ = -33.58 kJ/mol

ΔG°’ = -16.79 kJ/mol

ΔG°’ = 33.58 kJ/mol

ΔG°’ = 95.48 kJ/mol

Answer 1

(j) At pH greater than 12, polylysine forms the helical structure due to

• the high concentration of OH ions in solution reduces the electrostatic repulsion between the R groups.
• the lysine residues are uncharged (at higher pH due to deprotonation of side-chain) which eliminates the electrostatic repulsion between the R groups.
• high pH eliminates the polarity across the alpha helix (with increasing pH the the electrostatic potential across the helix decreases)

(k) Solution is in the attached picture