Which of the Following Amino Acids Has an Ionizable R-Group

Question

Which of the following amino acids has an ionizable R-group with a pKanear neutral pH?
A) histidine
B) serine
C) aspartic acid
D) lysine
E) tyrosine

Accepted Answer

Histidine has an ionizable R-group (imidazole side chain) with a pKa near neutral pH (around 6.0), making it unique among the amino acids listed for its ability to serve as a proton donor or acceptor near physiological pH.

Which of the following amino acids has an ionizable R-group with a pKa near neutral pH?

Which of the following amino acids has an ionizable R-group with a pK_a near neutral pH?