Proline was the second amino acid synthesized before its presence as a product of the hydrolysis of the protein molecule was established. Willstatter, investigating the position of the carboxyl group in N-methylproline, first obtained this amino acid in 1900. Next year, Fischer published a synthesis of Proline from phthalimide propylmalonic ester by hydrolyzing casein with hydrochloric acid, with consequent esterification of the amino acids and the next distillation of the esters.

Chemical Structure of L-Proline

Structure of Proline

Identifiers and properties of Proline

IUPAC Name: (2S)-Pyrrolidine-2-carboxylic acid
Symbol: Three-letter code - Pro. One-letter code - P
Molecular Weight (Molar Mass): 115.13046 g/mol
Molecular Formula (Structural Formula): C5H9NO2
Canonical SMILES: C1CC(NC1)C(=O)O
Isomeric SMILES: C1C[C@H](NC1)C(=O)O
CAS Number: 147-85-3
MDL Number: MFCD00064318
Melting point: 228 °C
RNA codons: CCA, CCC, CCG, CCT
Solubility in water: 1623 g/L (25 °C); pKa - 1,99; pKb - 10,60
Rf value in n-butanol/acetic acid/water = 12:3:5 - 0.43
2D Molfile: Get the molfile
3D PDB file: Get the PDB file
Other names: 2-Pyrrolidinecarboxylic acid; (S)-Pyrrolidine-2-carboxylic acid

What is the role of Proline?

In fact, Proline is an essential component of collagen, and therefore is vital for proper functioning of joints and tendons. Besides, this amino acid helps maintain and strengthen heart muscles. Since Proline is a non-essential amino acid, which can be obtained from Glutamic acid, it is not necessary to be obtained additionally from dietary sources. In other words, human body is able to produce enough Proline for its own use. Like many other amino acids, Proline can be easily utilized as an energy source for the body.

Benefits of Proline

As for the benefits of this amino acid, Proline is recognized to be beneficial in two critical ways. Firstly, it is responsible for the creation of collagen, and secondly, it helps diminish arterioscleroses.

As you understand, a lack of Proline can cause a number of problems in the human body. For example, this can lead to multiple strains or tears in the soft tissues of the human body. In addition, a lack of this amino acid can also be liable for slower than normal healing.

As for atherosclerosis, Proline prevents its appearance the following way: every time your heart beats, your arteries expand and contract unless some fat is built up onto the walls of the arteries, which condition is known as atherosclerosis. In this case, Proline is able to help your artery be able to effectively stretch out and go back to its normal size and shape. This ability of the amino acid is essential for maintaining the appropriate pressure levels throughout the body, as well as for the long-distance transportation of blood around the circulatory system.

Food sources

Proline is particularly abundant in protein-rich foods. Here are some examples of foods that contain proline.

Meat. Proline is found in abundance in meat, including beef, chicken, pork, and lamb.

Dairy Products. Dairy foods such as milk, cheese, and yogurt contain proline.

Eggs, especially egg whites, are a good source of proline.

Fish, such as salmon, tuna, and cod, contain proline.

Legumes. Some legumes, like lentils and chickpeas, contain proline.

Soy Products. Foods made from soy, such as tofu and soybeans, are sources of proline.

Nuts and Seeds. Almonds, pumpkin seeds, and sunflower seeds contain proline.

It's important to note that the exact proline content can vary depending on factors like the specific type of food, how it's prepared, and other ingredients in the dish. If you have specific dietary concerns or requirements, it's advisable to consult with a nutritionist or healthcare professional who can provide personalized guidance based on your individual needs. Additionally, nutritional databases and food labels can be helpful resources for more precise information on the proline content of specific foods.