Hi, I'm a little confused about the term "naturally occurring amino acid". Does this refer to the chirality of the amino acid at all? Some sources say that L-isomers are the "naturally occurring" amino acids, but others seem to suggest that this is a misconception.

 

I've been given the structure of GABA (gamma aminobutyric acid) and asked if it is considered a naturally occuring amino acid. I know that it's synthesized from glutamate, has no chiral carbon and is not a protein forming amino acid... does that mean its not naturally occurring?

 

Cheers,

rorosingsong

Actually you are already halfway through the correct answer. In short, it is the distinction between naturally occuring and codogenic (or proteinogenic) amino acids.

 

Sometimes they are used interchangeably (wrongly imo).