Polylysine is a random coil when the pH is less than 11, while it forms an α-helix if the pH is raised to greater than 12. This is because at pH 12:
A) the lysine residues are negatively charged which electrostatically stabilizes the helix.
B) the positive charges on the lysine residues stabilizes the α-helix.
C) the lysine residues are neutral which eliminates electrostatic repulsion between the R groups.
D) the high concentration of OH− ions in solution reduces the electrostatic repulsion between the R-groups.
E) the lysine side chain changes configuration with pH.

Question

Quizplus · Accepted Answer

At pH 12, the lysine residues are neutral because their side chains (which are basic) have accepted a proton, eliminating the electrostatic repulsion between the R groups and stabilizing the α-helix structure.

Polylysine Is a Random Coil When the PH Is Less