Here Are Two Related Observations About the Conformations of Synthetic

Essay

Here are two related observations about the conformations of synthetic peptides as a function of pH.
​
The synthetic peptide poly-L-lysine (. . .Lys-Lys-Lys-Lys. . .) adopts an -helical conformation at pH > 10, but as the pH is lowered to 7, the helix is converted into a random structure.
The synthetic peptide poly-L-glutamic acid (. . .Glu-Glu-Glu-Glu. . .) adopts an -helical conformation at pH < 3, but, as the pH is raised above 5, the helix is converted into a random structure.
Explain these two observations.