Proline (abbreviated as Pro or P; encoded by the codons CCU, CCC, CCA, and CCG) is an α -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. 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.
Appearance & Physical State
White crystalline powder
Density
1.35
Melting Point
228-233ºC
Boiling Point
252.2ºC at 760 mmHg
Flash Point
106.3ºC
Refractive Index
-85 ° (C=4, H2O)
Water Solubility
soluble
Stability
Stable. Incompatible with strong oxidizing agents.
