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Acidity and basicity in amino acids

  1. Apr 12, 2013 #1
    Hello! I'm having a hard time understanding the acidity and basicity of amino acids.

    I read this: the acidic group in an amino acid is NOT the -COOH but the NH3+ and the basic group is COO- and not the NH2... why?

    Thanks in advance!
  2. jcsd
  3. Apr 12, 2013 #2


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    Just revise about "conjugate acids and bases" e.g.

    http://chemwiki.ucdavis.edu/Physical_Chemistry/Acids_and_Bases/Conjugate_Acids-base_Pairs#Conjugate_Acid-Base_Pairs [Broken]

    "The conjugate acid of a base is formed when the base gains a proton" etc.
    Last edited by a moderator: May 6, 2017
  4. Apr 12, 2013 #3


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    The proper term for 'basicity' is 'alkalinity'.
  5. Apr 14, 2013 #4


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    Individual amino acids exist as zwitterions in plain water. Therefore, the acid part will be the group with the protons and the base will be the group capable of accepting a proton. You haven't asked about the side groups yet. That's where it gets interesting.
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