Physical properties of proteins. The most important chemical properties of proteins

Before you talk about the most important physical and chemical properties of a protein, you need to know what it consists of, what its structure is. Proteins are an important natural biopolymer, amino acids serve as the foundation for it.

What are amino acids

These are organic compounds, which include carboxyl and amine groups. Thanks to the first group, they have carbon, oxygen and hydrogen, and the other - nitrogen and hydrogen. Alpha amino acids are considered the most important because they are needed for the formation of proteins.

Essential amino acids called proteinogenic exist. So they are responsible for the appearance of proteins. There are only 20 of them, and they can form countless protein compounds. Moreover, none of them will be completely identical to the other. This is possible thanks to the combinations of elements that are in these amino acids.

Their synthesis does not occur in the body. Therefore, they get there with food. If a person receives them in insufficient quantities, then the normal functioning of various systems may be disrupted. Proteins are formed due to the polycondensation reaction.

Proteins and their structure

Before moving on to the physical properties of proteins, it is worthwhile to give a more precise definition of this organic compound. Proteins are one of the most significant bioorganic compounds that are formed due to amino acids and are involved in many processes in the body.

The structure of these compounds depends on the order in which amino acid residues alternate. As a result of this, it is as follows:

• primary (linear);
• secondary (spiral);
• tertiary (globular).

Their classification

Due to the huge variety of protein compounds and the varying degrees of complexity of their composition and different structures, for convenience there are classifications that rely on these signs.

In their composition, they are as follows:

• simple;
• complex, which are divided in turn into:

1. a compound of protein and carbohydrates;
2. the combination of proteins and fats;
3. connection of protein molecules and nucleic acids.

By solubility:

• water soluble;
• fat soluble.

A small characteristic of protein compounds

Before moving on to the physical and chemical properties of proteins, it will be useful to give them a small characterization. Of course, their properties are important for the normal functioning of a living organism. In their initial state, these are solids that either dissolve in various liquids or not.

Briefly about the physical properties of proteins, then they determine many of the most important biological processes in the body. For example, such as transportation of substances, construction function, etc. The physical properties of proteins depend on whether they are soluble or not. That's just about these features and will be written later.

Physical properties of proteins

Above has already been written about their state of aggregation and solubility. Therefore, we pass to the following properties:

1. They have a large molecular weight, which depends on certain environmental conditions.
2. Their solubility has a wide range, as a result of which electrophoresis is possible - a method by which proteins are isolated from mixtures.

Chemical properties of protein compounds

Readers now know the physical properties of proteins. Now you need to talk about no less important, chemical. They are listed below:

1. Denaturation . Coagulation of protein under the influence of high temperatures, strong acids or alkalis. During denaturation, only the primary structure is retained, and all biological properties of the proteins are lost.
2. Hydrolysis . As a result of it, simple proteins and amino acids are formed, because the primary structure is destroyed. It is the basis of the digestive process.
3. Qualitative reactions to the determination of protein . There are only two of them, and the third is needed in order to detect sulfur in these compounds.
4. Biuret reaction. Proteins are exposed to a precipitate of copper hydroxide. As a result, staining in purple occurs.
5. Xanthoprotein reaction . Exposure is carried out using concentrated nitric acid. As a result of this reaction, a white precipitate is obtained, which upon heating turns yellow. And if you add an aqueous ammonia solution, an orange color appears.
6. Determination of sulfur in proteins . When the burning of proteins occurs, the smell of a "burnt horn" begins to be felt. This phenomenon is explained by the fact that they contain sulfur.

So, these were all the physical and chemical properties of proteins. But, of course, not only because of them are they considered the most important components of a living organism. They determine the most important biological functions.

Biological properties of proteins

We considered the physical properties of proteins in chemistry. But it is also worth telling about what effect they have on the body and why without them it would not function fully. The following are the functions of proteins:

1. enzymatic. Most reactions in the body occur with the participation of enzymes that are of protein origin;
2. transport. These elements deliver other important molecules to tissues and organs. One of the most significant transport proteins is hemoglobin;
3. structural. Proteins are the main building material for many tissues (muscle, integument, supporting);
4. protective. Antibodies and antitoxins are a special type of protein compounds that form the basis of immunity;
5. signaling. The receptors that are responsible for the functioning of the senses also have proteins in their structure;
6. stocking up. This function is performed by special proteins, which can be a building material and can be sources of additional energy during the development of new organisms.

Proteins are able to turn into fats and carbohydrates. But they can not become squirrels. Therefore, the lack of precisely these compounds is especially dangerous for a living organism. The energy released during protein assimilation is small and inferior to fats and carbohydrates in this regard. However, they are the source of essential amino acids in the body.

How to understand that the body lacks protein? A person's health is deteriorating, fast exhaustion and fatigue comes. Excellent sources of protein are various varieties of wheat, meat and fish products, dairy, eggs and some types of legumes.

It is important to know not only the physical properties of proteins, but also the chemical ones, as well as how important they are for the body from a biological point of view. Protein compounds are unique in that they are sources of essential amino acids that are necessary for the normal functioning of the human body.