Question

Given all 20 common amino acids have at least two oppositely charged groups, which statement is incorrect?
A) solutions of amino acids can act as buffers
B) all amino acids are zwitterions
C) all amino acids carry at least one charge across full range of titration curves
D) amino acid isoelectric points should be near neutrality
E) it is not possible to fully deprotonate amino acids

Answer 1

thinking it's E but not 100% sure