Description of amino acids

Chiral compounds occur when a carbon atom has four different things bonded to it. All but the simplest amino acids (glycine) are chiral because the alpha carbon has an amine group, a carboxylic acid group, and two different groups bonded to it. Some amino acids are even more complicated in that another carbon in the molecule is also chiral.

Name 2 amino acids that have a second chiral carbon atom.