Acid-Base Properties of Amino Acids
Investigate the pH-dependent protonation of amino acids.
Tasks
Create and optimize a glycine molecule (). Open Build Menu and select Add Hydrogens for pH... Choose different values of pH : 1,2,3,…,13 and note the effect of pH shift on electrical charge of glycine.
In a new View, create a (Glutamic acid - Lysine) dipeptide using Build Menu > Insert > Peptides... Set pH to 3 and calculate the correspondent electrical charge of the dipeptide. Do the same for pH=7 and 13.
When performing a paper electrophoresis at these pHs, in which direction will the dipeptide move (anode or cathode) ?
Solution
Glycine electrical charge according to pH shift:
pH<5: ; net charge =+1
5≤pH<10: ; net charge =0
10≤pH≤13: ; net charge =-1
Glu-Lys dipeptide:
Further readings
Categories:
Teaching
Updated: December 01, 2009
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This is a companion discussion topic for the original entry at https://avogadro.cc/teaching/acid_base_behaviour_of_amino_acids/