Which of these is a non-essential amino acid?
Proline (symbol Pro or P) is a proteinogenic amino acid that is used in the biosynthesis of proteins.
It is non-essential in humans, meaning the body can synthesize it from the non-essential amino acid L-glutamate.
Proline is the only proteinogenic amino acid with a secondary amine, in that the alpha-amino group is attached directly to the main chain, making the α carbon a direct substituent of the side chain.
L-Proline is an osmoprotectant and therefore is used in many pharmaceutical, biotechnological applications.