D-Amino Acids
This view of D-alanine illustrates a simple rule for distinguishing D-amino acids from the naturally-occuring L-amino acids: With the carboxyl group facing you, D-amino acids have their side chain on the right. Substitution at the other position on the a-carbon would result in a L-amino acid. Verify this rule by viewing L-alanine on the right as follows: Use the same display and coloring for both models; then adjust the L-alanine model so that the carboxyl and amino groups are oriented as shown here. Note that the two models are mirror images of one another.
