Howdy,

Question

I need suggestion on this question.
You spotted a mixture of Ala, Arg, Asp, Glu, His, and Lys on an isoelectric focusing where the left and right sides have pH 2 and 13, respectively. After a while, all amino acids stop migration on the strip. Answer an amino acid (in three-letter code) whose band shows up the third from the left (i.e., lower pH).
Hint: you need to calculate their pI based on the pKa value, pK1 (i.e., pKa of COOH) and pK2 (i.e., pKa of NH3+).

So I evaluated using the pI of the amino acids from a standard table because when I tried calculating pI for some amino acids using the pka of NH3+ and COO- it didn’t match the standard table . And I got Ala ( alanine ) to be the third AA. Is there a mistake?

Thanks!