L-series amino acids

It is very important to realise that when drugs or medicines are administered to the body there is the opportunity for chiral interactions. This is because the human body is composed of enzymes and receptors that are protein in nature. These proteins are polymers of 20 or so naturally occurring amino acids. With the exception of glycine, all of these amino acids are chiral (all are L-series amino acids - see later) and it must be expected that a chiral drug will interact with these chiral receptors differently from its enantiomer. It is often the case that if a racemic mixture of a chiral drug is administered, only one enantiomer will be active, while the other will be... 

For amino acids the situation is analogous. When the Fischer projection is drawn (carbon chain vertical with most oxidised carbon at the top) all of the natural amino acids found in human proteins are found to have the NHj group on the left-hand side of the Fischer projection and are therefore similar in configuration to l-(—)-glyceraldehyde. These amino acids are consequently known as L-series amino acids (Figure 4.9). 

Figure 4.9 Fischer projection of L-series amino acids.

---