|Molecular weight||115.132 g/mol|
|Names and Identifiers|
|CAS Registry Number||147-85-3|
Proline is a proteinogenic amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated NH2+ form under biological conditions), an α-carboxylic acid group (which is in the deprotonated −COO− form under biological conditions), and a side chain pyrrolidine, classifying it as a nonpolar (at physiological pH), aliphatic amino acid. It is non-essential in humans, meaning the body can synthesize it from the non-essential amino acid L-glutamate. It is encoded by all the codons starting CC (CCU, CCC, CCA, and CCG).
Proline is the only proteinogenic amino acid with a secondary amine, in that the alpha-amino group is attached directly to the side chain, making the α carbon a direct substituent of the side chain.