The number of chiral carbon(s) present in the peptide, $Ile-Arg-Pro$, is......

$\beta-$pleated sheets of polypeptide chains are present in

For an amino acid,the ionization constant for the carboxyl group is $pK_{a_1} = 2.34$ and for the ammonium ion is $pK_{a_2} = 9.6$. At what $pH$ will the isoelectric point of the amino acid be?

Which of the following amino acids is optically inactive?

For $\alpha$-amino acids having the structure $R-CH(NH_2)-CO_2H$,which of the following statements are true?
$(a)$ Water solubility is maximum at a $pH$ when concentrations of anions and cations are equal.
$(b)$ They give ninhydrin test.
$(c)$ On reacting with nitrous acid,they give off $N_2$.

Zwitter ion is formed by