All amino acids have two ionizable groups (an alpha-amino group with pKa~9.3, and an alpha-carboxyl group with pKa~2.2). Lysine also has an ionizable side-chain (R) with a pKa of 10.5.

What percentage of the Lysine side chain is deprotonated at pH 11.5?


Please show work.





0.099%




9.1%




0.99%




90.9%