The titration curve for lysine is: b Which of the following statements is correct concerning the isoelectric point of lysine? The amino acid carries a net charge at all pH. Lysine has no net charge around pH 9.75, where all the functional groups are neutral. Lysine has no net charge around pH 5.53, where the carboxyl group is deprotonated and the -amino group is protonated. Lysine has no net charge around pH 9.75, where the carboxyl group is deprotonated and the -amino group is protonated. Lysine has no net charge around pH9.75, where the carboxyl group is deprotonated and the a-amino group is protonated