Role and use about proline

Posted by beauty33 on December 28th, 2021

Proline (abbreviated as Pro or P), the chemical formula is C5H9NO2, the molecular weight is 115.13, and it is a cyclic imino acid. α-Imino acid, neutral, isoelectric point is 6.30, water solubility is greater than any amino acid, about 162 g can be dissolved in 100 g of water at 25°C. It is easy to deliquesce and hard to get crystals, and it has a sweet taste. Co-heating with the ninhydrin solution produces a yellow compound. Once in the peptide chain, hydroxylation can occur to form 4-hydroxyproline, which is an important component of animal collagen. Hydroxyproline is also present in a variety of plant proteins, especially related to the formation of cell walls. Plants often have obvious accumulation of proline under drought, high temperature, low temperature, salinity and other adversities. It is widely used in clinical, biological materials, industry, etc.

We know that proline has three forms: DL-proline, L-proline and D-proline. The commonly referred to as proline is L-proline, which is a naturally occurring amino acid. The product is a columnar crystal. It decomposes rapidly when heated to 215-220?. It is soluble in hot water and ethanol. Slightly sweet and hygroscopic. Racemization in alkaline solution. [α] D25-86.5° (water), -60.4° (5N hydrochloric acid). Distributed in a variety of proteins. It is a mid-content amino acid in marine plankton; it also exists in sea water, particulate matter and marine sediments.


Proline is a polar molecule from the perspective of the entire molecular structure, but it is a non-polar amino acid. This is because the polarity of amino acids is judged based on the nature of the side chain rather than the entire amino acid molecule. In reality, there are many non-polar amino acids like this that are polar molecules.

Role and use

Pharmaceutical industry application

Amino acid drugs. One of the raw materials for compound amino acid infusion. It is used for protein supplementation after malnutrition, protein deficiency, severe gastrointestinal diseases, burns and surgery. No obvious side effects.

Plant cold resistance

Proline (Pro) is one of the components of plant protein, and can be widely present in plants in a free state. Under drought, salinity and other stress conditions, proline accumulates in large amounts in many plants. In addition to being an osmotic regulator in plant cytoplasm, the accumulated proline also plays an important role in stabilizing the structure of biological macromolecules, reducing cell acidity, detoxifying ammonia, and regulating cell redox as an energy reservoir.

Under adversity conditions (drought, saline-alkali, heat, cold, freezing), the content of proline in plants increases significantly. The proline content in plants reflects the stress tolerance of plants to a certain extent, and varieties with strong drought resistance tend to accumulate more proline. Therefore, the determination of proline content can be used as a physiological index for drought resistance breeding. In addition, because proline is extremely hydrophilic, it can stabilize the protoplast colloid and the metabolic process in the tissue, so it can lower the freezing point and prevent cell dehydration. Under low temperature conditions, the increase of proline in plant tissues can improve the cold resistance of plants. Therefore, it can also be used as a physiological index for cold resistance breeding.


In vivo effects

In organisms, proline is not only an ideal osmotic adjustment substance, but also as a protective substance for membranes and enzymes and a free radical scavenger, thereby protecting the growth of plants under osmotic stress. The accumulation of another important osmotic adjustment substance in the body in the vacuole, proline can also play a role in regulating the cytoplasmic osmotic balance.

Industrial application

In the synthesis industry, proline can participate in inducing asymmetric reactions and can be used as a catalyst for hydrogenation, polymerization, and water-mediated reactions. When used as a catalyst for such reactions, proline has the characteristics of strong activity and good stereospecificity.

Application in other fields

Proline and its derivatives are usually used as symmetric catalysts in organic reactions. The reduction of CBS and the aldol condensation reaction of proline catalyzed are prominent examples.

During brewing, protein is rich in proline combined with polyphenols, which can produce haze (turbidity).

Synthetic raw material of cholesterol ester inhibitor.

Flavoring agent, which reacts with the sugar to produce an amino-hydrogen radical reaction, which can produce a substance with a special fragrance.

Experimental use

Proline, in its naturally occurring form, is one of the main components of collagen. The DL-type uses gelatin as raw material and undergoes hydrochloric acid hydrolysis and other multi-step treatments to obtain the product hydrochloride. It is a biochemical reagent, used for biochemical and nutritional research, microbial test, and preparation of culture medium. L-form is prepared by esterification and reduction of L-glutamic acid and absolute ethanol.

Qualitative repair

According to a recent study by the University of Illinois, in the protein center of tooth enamel, a simple repetition of amino acids makes teeth stronger and more elastic.

In amphibians and animal models, the researchers compared proline repeats. They found that when the repetition is short, such as in frogs, the teeth will not produce enamel prism, which is important for the firmness of the teeth. Conversely, when protein repeats are longer, they gather a series of molecules to help enamel crystals grow.

The results of this research were published on the online version of \"PLoS Biology\" on December 21, 2009. According to Tom Diekwisch, the head of the study, the professor of biology, the proline repeat is very surprising, which is also very important for understanding the structure and function of many natural proteins, such as mucins, anti- Antifreeze proteins, amyloid, prion protein, etc.

During the growth of tooth enamel, it will be surrounded by foamy protein blocks. The size of protein foam varies in different animals, ranging from 5 nanometers for cows to 20 nanometers for mice and 40 nanometers for frogs. This finding indicates that the longer the proline repeat, the larger the protein foam. In addition, the smaller the protein foam, the longer the enamel crystals.

Researchers hope that these findings can help research in other important scientific fields, including the treatment of neurodegenerative diseases. In addition, this discovery may help design new tooth enamel so that people can have a healthy enamel layer.

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