The enzyme used in the above reaction is

$\,\begin{array}{*{20}{c}}
{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,COOH}\\
{\,\,\,\,\,\,\,\,\,|}\\
{\mathop {N{H_3}}\limits^{\,\, \oplus } - C - H}\\
{\,\,\,\,\,\,\,\,\,\,|}\\
{\,\,\,\,\,\,\,\,\,\,R}
\end{array}\,\,\,$