Haemoglobin is

The correct statement in respect of the protein haemoglobin is that it

Denaturation of proteins leads to loss of its biological activity by

$HC\equiv CH$ $\xrightarrow[HgSO_4]{H_2SO_4} (A)$ $\xrightarrow[(1) NH_3 + HCN]{(2) H_3O^{\oplus}} (B);$ The product $(B)$ of the given reaction is:

Assertion $(A)$: An optically active amino acid can exist in three forms depending on the $pH$ of the solution.
Reason $(R)$: Amino acids contain both acidic and basic groups; they exist as a zwitterion in aqueous medium,anionic form in basic medium,and cationic form in acidic medium.

Which of the following is not a function of proteins?