The main structural linkage of protein is

Sulphur $(S)$ containing amino acids from the following are:
$(a)$ isoleucine
$(b)$ cysteine
$(c)$ lysine
$(d)$ methionine
$(e)$ glutamic acid

Assertion : Proteins are made up of $\alpha-$ amino acids.
Reason : During denaturation,secondary and tertiary structures of proteins are destroyed.

Within the list shown below, the correct pair of structures of alanine in $pH$ ranges $2-4$ and $9-11$ is:
$I$. $H_{3}N^{+}CH(CH_{3})COOH$
$II$. $H_{2}NCH(CH_{3})COO^{-}$
$III$. $H_{3}N^{+}CH(CH_{3})COO^{-}$
$IV$. $H_{2}NCH(CH_{3})COOH$

Can an enzyme be called a polymer?

The functional groups present in Asparagine,a nonessential amino acid,are