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%