In which of the following processes does protein $NOT$ participate?

$1.78 \ g$ of an optically active $L$-amino acid $(A)$ is treated with $NaNO_{2} / HCl$ at $0^{\circ}C$. $448 \ cm^{3}$ of nitrogen at $STP$ is evolved. $A$ sample of protein has $0.25 \%$ of this amino acid by mass. The molar mass of the protein is

In the given pentapeptide, find out an essential amino acid $(Y)$ and the sequence present in the pentapeptide: Choose the correct answer from the options given below:

Observation of "Ruhemann's purple" is a confirmatory test for the presence of

$A$ nanopeptide contains $\dots$ peptide linkages.

Which of the following amino acids will give a violet-coloured complex with neutral ferric chloride solution?