Descrive the term D- and L-configuration used for amino acids with exmaples.

Explanation

Consider the following configurations (I and II) of `alpha`-amino acids
`H_(2)N-underset("L-Amino acid")underset(I)underset(R)underset(|)overset(COOH)overset(|alpha)(C)-H`
`H-underset("D-Amino acid")underset(II)underset(R)underset(|)overset(COOH)overset(alpha|)(C)-NH_(2)`
If the `NH_2` group on the `alpha` carbon is oriented towards left (as in structure I), it is referred to as L- amino acid and if `NH_2` group is oriented towards right (as in structure II), it is referred to as D-amino acid.