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Homework Help: Ionic bonds in amino acids

  1. Oct 22, 2007 #1
    i am doing revision for my exams aand was wondering which one of these, high temperature, hydrolysis or pH change would break the ionic bond between amino acids.

    I would go for pH change. I have no reason, it's just instinctively.
  2. jcsd
  3. Oct 22, 2007 #2
    I'll tell you this. One of those cannot be right just based on what you should know as the definition of all the terms involved. Think about the definitions and you'll see what I mean.
  4. Oct 22, 2007 #3
    i think hydrolysis cannot be right. which definition d'you mean? that of an ionic bond?

    pH change will affect the ionic bond bevause of the chamnge in concentratuioin of H+ ions.

    I hope i'm righjt.
  5. Oct 23, 2007 #4
    High temperature will break the bond, while a change in pH will affect the ionic bond (as said by Kushal).
  6. Oct 24, 2007 #5
    Yes the definition of hydrolysis is the breaking of a covalent bond through the addition of a water molecule. One molecule gets an OH and the other gets an H.
  7. Jan 4, 2008 #6
    Hydrolysis will break a peptide bond between amino acids, high temperature will break hydrogen bonds between amino acids so in the case of an enzyme the tertiary structure is broken, and so the active site changes, so enzyme substrate complexes cannot form. pH will effect the ionic bonds.

    Kushal what exam board are you on? AQA Biology B unit 1?
  8. Jan 5, 2008 #7
    aww no, i'm on cambridge A level. i live in mauritius, and we stick to cambridge here, lol.
  9. Jan 7, 2008 #8


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    Could you explain what is meant by the ionic bond between amino acids?
  10. Jan 7, 2008 #9
    the amino acids can exist as zwitter ions; the carboxylic group releases a proton to give COO- while the amine group accepts the proton, giving NH3+. when zwitter ions with opposite charge occur close to each other in the protein structure, there is an electrostatic attraction, called the ionic bond.

    hey chemisttree congrats for your guru award!!! you deserve it....
  11. Jan 7, 2008 #10


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    Ahhh! Thats what I thought you meant. You are definitely talking about individual amino acids.

    When you adjust the pH, you will either pull off a proton (pH up) from the ammonium ion portion or donate one (pH down) to the carboxylate. Yes, this would affect ionic bonding. Since the ionic bond isn't really very strong, an increase in temperature can also overcome this bonding. Of course, I am talking about ionic bonds between separate molecules of amino acids.

    If the question is referring to peptides (or proteins) and is asking how one would break the bonds between individual amino acids within the peptide or protein, hydrolysis seems most appropriate.

    Exactly as Spirochete and CrawfordK have indicated.

    Thanks for the congrats! I'm still getting used to the idea of being nominated and especially the medal. After seeing the efforts of the other winners (past and present), I feel a bit unworthy.
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