Image of L-Proline | C5H9NO2 | Supreme Pharmavet
Chemical FormulaC5H9NO2
Molecular weight115.132 g/mol
Names and Identifiers
PubChem Link
Traditional NameL-Proline
CAS Registry Number147-85-3


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.

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