Question

Consider the amino acid, glycine, in its fully protonated form ⁺ H3NCH2CO2H, where the pKa₁ = 2.35 and pKa₂ = 9.78.

a) K_a2 is the equilibrium constant for the second dissociation of ⁺ H3NCH2CO2H. Write the chemical equation that illustrates this equilibrium.

b) Write the structure for the major species at pH = 1.35.

c) Write the structure for the major species at pH = 3.35.

d) Write the structure for the major species at pH = 10.78.

e) Calculate the isoelectric point, pI.

f) What is the name of the technique that could be used to separate the different structures of glycine.

Answer 1

M = cxycoon on the mov=c4cool e bran HT Бka, IN-C4 - Coo And as The second acid dissociation Constant is Pres 9-10 for glycin. New-coo or N-C-005 Pka, 29-00 Ouv- tet I (B) = The first acid dissociation Constant i ų pra =23 for glycine so at -Pe 1.35 major species well cationic H -CH=Coon e At br 3.35 more than half - species will be zwitterionic I rent - CH₂ -cos

6. At pre 3.35 more than half - species will be zwitterionic - q - CH -coo O) At par = 10.78 will be anionic. major species S hn-Cha -coo of) Isoelectric point for glycine ÞIz pra, tbky 2 = 23 +9.6 2 = 6 C) Electrophoresis is the technique used . to separate different structure of glycine.