[" Incorrect statement among "],[" the following is "],[qquad [" The pKa of - COOH group in "],[" an a-amino acid is lower "],[" than the pKa of acetic acid."]],[" Proline is an example of "],[" aromatic heterocyclic ring "],[" containing amino acids "],[" There is two chiral centres "],[" in Leucine "],[" All naturally available amino "],[" acids are essential amino "],[" acids "]