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Help! need titration curve for Arginine

  1. Oct 23, 2004 #1
    I have a question

    When you do a titration curve for Arginine and you start it off in the acid exteme (low pH) does it gain anymore Hydrogens other than the one that always bonds to the COO- group? (so does it gain more than a +2 charge)

    To rephrase, do any of the other two Nitrogens (other than the one double bonded to the Carbon in the R-Group) gain additional hydrogens when it acts as a base.
  2. jcsd
  3. Oct 24, 2004 #2


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    Gold Member

    Yes, the formula should be written in low pH like that:


    I don't think that the terminal C(=NH)-NH2 group takes additional protons, since they seem to be amphoteric.

    But I have found this http://www.cem.msu.edu/~reusch/VirtualText/proteins.htm, mentioning that the [itex]C=NH[/itex] group protonates instead to give the same 2+ charge, which is logical as the nitrogen I mentioned is somewhat hindered to react with proton.

    I feel confident that the website will help you very much; I've liked it too.

    Take care.
    Last edited by a moderator: Apr 21, 2017
  4. Oct 24, 2004 #3
    thanks alot for the info :)
    Last edited: Oct 24, 2004
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