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**How to calculate the pI of a peptide??**

Hello everyone, I am hoping someone can shed some light on this question. I know the general idea behind it but i can't seem to put the nail in the coffin.

The sequence is ATLDAK and it asks to : Calculate its approximate pI

This is what i have so far:

...nT-A...T...L... D... A... K-... cT

pK...9.87......3.9...10.54...2.16

I know that there are 2 positive charges so this results in requiring to be deprotinated with two equivalents of base. I also know that the pI is given by the two amino acids that give the zwiterionic charge, or simply zero charge. However, how to identify those amino acids...?

Help please