Question 19.3: Peptide Bonds Show the reaction by which glycine and alanine......
Peptide Bonds Show the reaction by which glycine and alanine form a peptide bond.
\begin{matrix}~~\overset{H~}{|~}~~~\overset{~~~O}{~~||}\\H_{2}N-C-C-OH\\\underset{\underset{\mathrm{Glycine}}{\underset{}{\mathrm{H}}}}{|}~~~~~~\end{matrix}~~~~~~\begin{matrix}~~\overset{H~}{|~}~~~\overset{~~~O}{~~||}\\H_{2}N-C-C-OH\\\underset{\underset{\mathrm{Alanine}}{\underset{}{\mathrm{~~~~CH_{3}}}}}{|}~~~~~~\end{matrix}
Peptide bonds form when the carboxylic end of one amino acid reacts with the amine end of a second amino acid to form a dipeptide and water.
\begin{matrix}~~\overset{H~}{|~}~~~\overset{~~~O}{~~||}\\H_{2}N-C-C-OH\\\underset{H}{|}~~~~~~\end{matrix}~~~+~~~\begin{matrix}~\overset{~H}{~|}~~~\overset{~~~~O}{~~~||}\\H_{2}N-C-C-OH\\\underset{CH_{3}~~~~~}{|~~~~~~}\end{matrix}~~→~~\begin{matrix}~\overset{H}{|}~~~~~\overset{O}{||}~~~~~~~~~~~~~~~~~~\overset{H}{|}~~~~~~\overset{O}{||}\\H_{2}N-C-C-NH-C-C-OH\\\underset{H}{|}~~~~~~~~~~~~~~~~~~~~~~~~~\underset{CH_{3}~~~~~}{|~~~~~~}\end{matrix}~~~+~~~H_{2}O
This reaction can also take place between the -NH_{2} end of glycine and the -COOH end of alanine, producing a slightly different dipeptide (one with the amino acids in reverse order).