Practice question

Question

The C-terminal carboxyl group and the N-terminal amino group in amino acids have a dissociation constant (pKa) of 2.2 and 9 .2, respectively. The pKa of side chain carboxyl group in glutamic acid is 4.2 and side chain amino group in lysine is 10.2. The difference in isoelectric point (pi) of lysine and glutamic acid (rounded off to two decimal places) is