Answer to Question #150785 in Biochemistry for Taiwo

Question

1. Calculate the isoelectric point of glutamic acid. How does the isoelectric point of glutamic acid differ from glycine.
2. Illustrate the titration curve of lysine showing the cation, zwitterion and anion on the curve.

Answer 1

Part One of the Question

$PI=(Pka1+Pka3)/2$

$Pka1=2.19$

$Pka2=9.67$

$Pka3=4.25$

$PI=(2.19+4.25)/2$

$=6.44/2$

$=3.22$

PI of glycine is 5.97. It differs from glutamic acid since it has two hydrogens attached to the alpha carbon.

Part Two of the Question  

Glutamic Acid pH is 2.19. 

Adding an acid to a solution comprising the zwitterion, the carboxylate group arrests a hydrogen (H+) ion, and the amino acid becomes positively charged. 

Adding a base, it removes an ion of the H+ ion from the amino group of the zwitterion produces a negatively charged amino acid.