Question

Write the structure of all possible dipeptides which can be obtained from glycine and alanine.

Give the structure of all the possible dipeptides formed when the following two amino acids form a peptide bond.

Alanine

 

Glycine

Answer 1

\[\begin{array}{cc}
\ce{\underset{(Glycine)}{H2N - CH2 - COOH} + H2N - CH - COOH ->[-H2O] H2N - CH2 - CONH - CH - COOH}\\
\phantom{......................}|\phantom{...........................................}|\phantom{...}\\
\phantom{.........................}\ce{\underset{(Alanine)}{CH3}}\phantom{...................................}\ce{\underset{(Glycyl alanine)}{CH3}}\phantom{}
\end{array}\]

\[\begin{array}{cc}
\ce{H2N - CH - COOH + \underset{(Glycine)}{H2N - CH2 - COOH} ->[][-H2O] H2N - CH - CONH - CH2 - COOH}\\
\phantom{..}|\phantom{..................................................}|\phantom{.......................}\\
\phantom{}\ce{\underset{(Alanine)}{CH3}}\phantom{..........................................}\ce{\underset{(Alanyl glycine)}{CH3}}\phantom{................}
\end{array}\]

Therefore, two dipeptide structures are possible from glycine and alanine.

They are

1. glycyl alanine and
2. Alanyl glycine