Which one of the following statement is not ture?

Options

A. `alpha`-Carbon of `alpha`-amino acid is asymmetric
B. All proteins are found in L - form
C. Human body can synthesize all proteins they need
D. At `pH = 7` both amino and carboxylic groups exist in ionised form

Answer

D

Explanation

Only at the pH corresponding to the isoelectric point `(pI)`, the amino acid exist as a dipolar ion with zero net charge. Even though the naturally occuring chiral `alpha`-amino acids can exist as pairs of enantiomers, only L- amino acids are found in proteins.