$\begin{array}{*{20}{c}}
  {R\,\,\,\,\,\,\,\,\,} \\ 
  {|\,\,\,\,\,\,\,\,\,\,} \\ 
  {{H_3}\mathop {NCHCOOH}\limits^{ + \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} } 
\end{array}$  $\xleftarrow{{acid}}$  $\begin{array}{*{20}{c}}
  {R\,\,\,\,\,\,\,\,} \\ 
  {|\,\,\,\,\,\,\,\,\,} \\ 
  {{H_3}\mathop {NCHCO{O^ - }}\limits^{ + \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,} } 
\end{array}$ $\xrightarrow{{base}}$ $\begin{array}{*{20}{c}}
  {R\,\,\,\,\,\,\,\,} \\ 
  {|\,\,\,\,\,\,\,\,\,} \\ 
  {{H_2}NCHCO{O^ - }} 
\end{array}$