Physical properties of proteins. The most important chemical properties of proteins
Before talking about the most important physical andchemical properties of protein, you need to know what it consists of, what its structure is. Proteins are an important natural biopolymer, the basis for it are amino acids.
What are amino acids
These are organic compounds in whichinclude carboxyl and amine groups. Due to the first group they have carbon, oxygen and hydrogen, and the other - nitrogen and hydrogen. The most important are alpha-amino acids, because they are necessary for the formation of proteins.
There are essential amino acids thatcalled proteinogenic. So they are responsible for the appearance of proteins. They are only 20, and protein compounds they can form an infinite number. However, none of them will be completely identical to the other. This is possible due to the combinations of elements that are present in these amino acids.
Their synthesis does not occur in the body. Therefore, they get there together with food. If a person receives them in insufficient quantity, then the normal functioning of various systems may be disrupted. Proteins are formed due to the polycondensation reaction.
Proteins and their structure
Before proceeding to the physical properties of proteins,it is worth giving 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 take part in many processes occurring in the body.
The structure of these compounds depends on the order in which the amino acid residues alternate. As a result, it happens as follows:
- primary (linear);
- secondary (spiral);
- tertiary (globular).
Due to the huge variety of protein compounds and the varying complexity of their composition and different structure, for convenience, there are classifications that rely on these signs.
In their composition they are as follows:
- Complex, which are subdivided in turn into:
- a combination of protein and carbohydrates;
- the combination of proteins and fats;
- a combination of protein molecules and nucleic acids.
A small characteristic of protein compounds
Before moving on to the physical and chemicalproperties of proteins, it will be useful to give them a small characteristic. Of course, their properties are important for the normal functioning of a living organism. In their original state, they are solids that either dissolve in various liquids or not.
If we talk briefly about the physical properties of proteins, they are responsible for many of the most importantbiological processes in the body. For example, such as the transport of substances, building 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 further.
Physical properties of proteins
We have already written about their aggregate state and solubility. Therefore, we proceed to the following properties:
- They have a large molecular mass, which depends on certain environmental conditions.
- Their solubility has a large range, which makes electrophoresis possible, a method by which proteins are extracted from mixtures.
Chemical properties of protein compounds
Readers now know the physical properties of proteins. Now we need to talk about no less important chemical ones. They are listed below:
- Denaturation. Coagulation of the protein under the influence of high temperatures, strong acids or alkalis. With denaturation, only the primary structure is retained, and all the biological properties of proteins are lost.
- Hydrolysis. As a result, simple proteins and amino acids are formed, because the primary structure is destroyed. It is the basis of the digestive process.
- Qualitative reactions to protein determination. There are only two of them, and the third is needed in order to detect sulfur in these compounds.
- Biuret reaction.The proteins are affected by the precipitate of copper hydroxide. As a result, the color is violet.
- Xantoprotein reaction. The impact is carried out with the help ofconcentrated nitric acid. As a result of this reaction, a white precipitate is obtained, which turns yellow when heated. And if you add an aqueous ammonia solution, an orange color appears.
- Determination of sulfur in proteins. When there is a burning of proteins, the smell of burnt horn begins to be felt. This phenomenon is explained by the fact that they contain sulfur.
So, it was all the physical and chemical properties of proteins. But, of course, not only because of them they are considered to be the most important components of a living organism. They determine the most important biological functions.
Biological properties of proteins
We examined the physical properties of proteinsin chemistry. But it is also necessary to tell about the impact they have on the body and why without them it will not function fully. The following are the functions of proteins:
- enzymatic. Most of the reactions in the body take place with the participation of enzymes that have a protein origin;
- transport. These elements carry the delivery of other important molecules to tissues and organs. One of the most important transport proteins is hemoglobin;
- structural. Proteins are the main building material for many tissues (muscular, integumentary, supporting);
- protective. Antibodies and antitoxins are a special kind of protein compounds that form the basis of immunity;
- signaling. The receptors that are responsible for the work of the sensory organs also have proteins in their structure;
- storing. 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 proteins. Therefore, the lack of these compounds is especially dangerous for a living organism. The energy released during the assimilation of proteins is small and inferior in this respect to fats and carbohydrates. However, they are the source of essential amino acids in the body.
How to understand that the body lacks protein? At the person the state of health worsens, there comes a fast exhaustion and fatigue. Excellent sources of protein are various varieties of wheat, meat and fish products, dairy, eggs and some types of leguminous crops.
It is important to know not only the physical properties of proteins,but also chemical, as well as the importance they have 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.