Question 20.2: Predict the direction of migration (if any) toward the posit......
Predict the direction of migration (if any) toward the positively or negatively charged electrode for the following amino acids in solutions of the specified pH. Write “isoelectric” if no migration occurs.
a. Lysine at pH = 7.0
b. Glutamic acid at pH = 7.0
c. Serine at pH = 1.0
a. Lysine at pH = 7.0
\begin{matrix} H \\ H_{3}\overset{+}{N}-\overset{|}{\underset{|}{C}}-COO^{-} \\ \ \ \underset{|}{C} H_{2} \\ \ \ \underset{|}{C} H_{2} \\ \ \ \underset{|}{C} H_{2} \\ \ \ \underset{|}{C} H_{2} \\ ^{+}NH_{3} \ \ \end{matrix} \begin{matrix} Net \ positive \\ charge \ (2 \ “+” \ and \\ 1 \ “-”) \\ Migrates \ toward \\ negatively \ charged \\ electrode \end{matrix}
b. Glutamic acid at pH = 7.0
\begin{matrix} H \\ H_{3}\overset{+}{N}-\overset{|}{\underset{|}{C}}-COO^{-} \\ \ \ \underset{|}{C} H_{2} \\ \ \ \underset{|}{C} H_{2} \\ \ \ \ \ \ COO^{-} \end{matrix} \begin{matrix} Net \ negative \ charge \\ (1 \ “+” \ and \ 2 \ “-”)\\ Migrates \ toward \\ positively \ charged \\ electrode \end{matrix}
c. Serine at pH = 1.0
\begin{matrix} H \\ H_{3}\overset{+}{N}-\overset{|}{\underset{|}{C}}-COOH \\ \ \ \underset{|}{C} H_{2} \\ OH \end{matrix} \begin{matrix} One \ positive \ charge \\ Migrates \ toward \ negatively \\ charged \ electrode \end{matrix}