Amino acids are organic compounds whose molecules contain a basic amino group (-NH2) and a carboxyl group (-COOH). 

 

All amino acids except for glycine are “stereoisomers”. A stereoisomer is a compound than can occur in one of the forms – the L-form (left-handed form) and D-form (right-handed form) – which are mirror images of one another. 

 

Most of the amino acids manufactured today are L-amino acids. 

For some reason, the amino acids that make up the proteins in our bodies are all L-amino acids. It used to be thought that D-amino acids did not exist in the natural world, but scientists recently discovered that they do exist and perform a variety of functions. 

 

DL-amino acids also exist. Compromising mixtures of L- and D-amino acids, they are also called racemic mixtures. 

 

As mentioned above, most of the amino acids manufactured today are L-amino acids. This includes glutamate, which is used as an umami seasoning. Unless otherwise stated, all amino acids referred to here are L-amino acids.