Amide group is present in

Among the following,$L$-serine is

Which of the following tests is not used for testing proteins?

Hydrolysis of proteins gives

Assertion $(A)$: The denaturation of proteins can destroy all $1^{\circ}, 2^{\circ}$ and $3^{\circ}$ protein structures.
Reason $(R)$: Curdling of milk is due to denaturation of proteins.
The correct option among the following is

Which of the following is not an amino acid?