question_answer

The peptide linkage formed between glycine \[\left( N{{H}_{2}}C{{H}_{2}}COOH \right)\]and alanine (\[N{{H}_{2}}\underset{\begin{smallmatrix} |\\ C{{H}_{3}} \end{smallmatrix}}{\mathop{CH}}\,-COOH\]) to give glycylalanine can be shown as

A) \[N{{H}_{2}}-C{{H}_{2}}-NH-\underset{\begin{smallmatrix} |\\ C{{H}_{3}} \end{smallmatrix}}{\mathop{CH}}\,-COOH\]

B) \[N{{H}_{2}}-C{{H}_{2}}-CONH-\underset{\begin{smallmatrix} |\\ C{{H}_{3}} \end{smallmatrix}}{\mathop{CH}}\,-COOH\]

C) \[{{H}_{2}}NCOC{{H}_{2}}-\underset{\begin{smallmatrix} |\\ C{{H}_{3}} \end{smallmatrix}}{\mathop{CH}}\,-CONH\]

D) \[HOOC-C{{H}_{2}}-NH-NH-\underset{\begin{smallmatrix} |\\ C{{H}_{3}} \end{smallmatrix}}{\mathop{CH}}\,-COOH\]

Correct Answer: B

Solution :

The peptide linkage formed between glycine \[\left( {{H}_{2}}N-C{{H}_{2}}-COOH \right)\] and \[\underset{\begin{smallmatrix} |\\ C{{H}_{3}} \end{smallmatrix}}{\mathop{\left( {{H}_{2}}\underset{{}}{\mathop{NCH}}\,-COOH \right)}}\,\]alanine  to give glycylalanine can be shown as