How to calculate the pI of a peptide?

  1. 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 cant 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
     
  2. jcsd
Know someone interested in this topic? Share a link to this question via email, Google+, Twitter, or Facebook