Types of protein structure and their functions

In theory Oparin-Haldane life on our planet originated from coacervate droplets.She was a protein molecule.That is, it can be concluded that these chemicals - the basis of all life that exists today.But what are a protein structure?What role they play in the body and life of humans?What types of proteins exist?Try to understand.

Proteins: general concept

In terms of the chemical structure of a molecule of the substance considered is the sequence of amino acids linked together by peptide bonds.

Each amino acid has two functional groups:

• carboxyl COOH;
• amino group -NH2.

That's between them and is formed due to different molecules.Thus, the peptide bond has the form -CO-NH.A protein molecule may contain hundreds or thousands of such groups, it would depend on the specific substance.Types of proteins are very diverse.Among them are those that contain amino acids which are essential for the organism, and hence must be ingested with food.There are some species that perform important functions in the cell membrane and its cytoplasm.Also highlights the nature of the biological catalysts - enzymes, which are also protein molecules.They are widely used in everyday life of human and not only involved in the biochemical processes of living beings.

molecular weight of the compounds in question may range from a few dozen to a million.Because the number of monomer units in the polypeptide chain infinitely large and depends on the particular substance.Protein in pure form, in its native conformation, can be seen when considering the egg raw.Light yellow, transparent thick colloid mass, which is located inside the yolk - this is the desired substance.The same is said of skim cheese, this product is also almost pure protein in its natural form.

However, not all of the subject compounds have the same spatial structure.In total there are four organizations molecule.Types of protein structures determined by its properties and talk about the complexity of the structure.It is also known that a more spatially entangled molecules undergo rigorous processing in humans and animals.

Types of protein structures

total there are four.Consider what constitutes each of them.

1. Primary.It is typically a linear sequence of amino acids joined by peptide bonds.No spatial twisting, spiraling no.The number of units included in the polypeptide may be up to several thousand.Types of proteins with similar structure - glitsilalanin, insulin, histone, elastin, and others.
2. secondary.It comprises two polypeptide chains which are twisted helically and are oriented towards each other is formed by turns.At the same time there are between the hydrogen bonds that hold them together.Thus is formed a single protein molecule.Forms of this type the following proteins: lysozyme, pepsin and others.
3. tertiary conformation.It is a densely packed and compactly assembled in a tangle secondary structure.Here, there are other types of interaction, in addition to hydrogen bonds - this is the van der Waals interaction and the forces of electrostatic attraction, hydrophilic-hydrophobic contact.Examples of structures - albumin, fibroin, silk protein and other.
4. Quaternary.The most complex structure consists of several polypeptide chains twisted into a spiral, rolled into a ball and combined together in a globule.Examples such as insulin, ferritin, hemoglobin, collagen, illustrate just such a conformation of proteins.

If we consider all of the detailed structure of molecules with a chemical point of view, the analysis will take a long time.Because in fact the higher the configuration, the more difficult and confusing its structure, the more types of interactions observed in the molecule.

denaturation of the protein molecules

One of the most important chemical properties of the polypeptides is their ability to break down under the influence of certain conditions or chemical agents.For example, widely different types of protein denaturation.What is the process?It is the destruction of the native protein structure.That is, if the original molecule had a tertiary structure, the special agents after the action it will collapse.However, the sequence of amino acid residues in the molecule remains intact.Denatured proteins quickly lose their physical and chemical properties.

What agents can lead to the destruction of the process of conformation?There are several.

1. temperature.When heated, the gradual destruction of the quaternary, tertiary, secondary structure of the molecule.Visually, it is possible to observe, for example, in a conventional frying an egg.The resulting "protein" - is the primary structure of the polypeptide of albumin, which was in the crude product.
2. radiation.
3. Action strong chemical agents: acids, alkalis, salts of heavy metals, solvents (eg, alcohol, ether, benzene and other).

This process is sometimes called fusion molecule.Types of protein denaturation depends on the agent, the action of which it came.At the same time, in some cases, there is a reverse process considered.This renaturation.Not all proteins are able to restore back to its structure, but much of it can do it.So, chemists from Australia and the United States implemented the renaturation of boiled chicken eggs with the help of some of the reagents and the method of centrifugation.

This process is important for living organisms for the synthesis of polypeptide chains ribosomes and rRNA in the cells.

hydrolysis of the protein molecule

Along with the denaturation of proteins characteristic of another chemical properties - hydrolysis.This is also the destruction of the native conformation, but not to the primary structure, and to completely separate the amino acids.An important part of the digestive system - the hydrolysis of protein.Types hydrolysis following polypeptides.

1. chemical.Based on the action of acids or alkalis.
2. biological or enzymatic.

However, the essence of the process remains the same and does not depend on what kind of protein hydrolysis are taking place.This produces amino acids which are transported by all cells, organs and tissues.Their further participation in the transformation is the synthesis of new polypeptides have those required specific organism.

in an industrial process of hydrolysis of protein molecules are used just to obtain the desired amino acids.

functions of proteins in the body

Different types of proteins, carbohydrates, fats are vital components for the normal life of any cell.And this means that the whole organism.Therefore, their role is largely explained by the high degree of importance and ubiquity within living beings.There are several basic functions of the polypeptide molecules.

1. catalyst.It is carried enzymes which have proteinaceous structure.About them say later.
2. Structure.Types of proteins and their functions in the body primarily affect the structure of the cell and its shape.In addition, the polypeptides in this role, to form the hair, nails, mollusk shells, feathers.They are certain valves in the cell body.Cartilage also consist of these types of proteins.Examples: tubulin, keratin, actin, and others.
3. Regulatory.This function is shown in polypeptides participation in processes such as transcription, translation, cell cycle, splicing, mRNA and other reading.They all play an important role of regulator.
4. warning.This function is performed by proteins located in the cell membrane.They transmit different signals from one unit to another, and this leads to a post tissue together.Examples: cytokines, insulin, growth factors, and others.
5. Transportation.Some types of proteins and their functions that they perform, are vitally necessary.This happens, for example, the protein hemoglobin.It transports oxygen from cell to cell in the blood.For a man, he is irreplaceable.
6. Spare or Reserve.Such polypeptides accumulate in plants and animal eggs as a source of additional power and energy.Example - globulins.
7. propulsion.A very important feature, especially for protozoa and bacteria.After all, they are able to move only with the help of flagella or cilia.And these organelles by nature is nothing but proteins.Examples of such polypeptides include: myosin, actin, and other kinesin.

It is clear that the function of proteins in the human body and other living beings are very numerous and important.This confirms once again that without connections can not be considered by us life on our planet.

protective function of proteins

polypeptides can protect against various influences: chemical, physical and biological.For example, if the body would be threatened as a virus or bacterium, having the nature of an alien, the immunoglobulins (antibodies) come to them "in the fight", performing a protective role.

If we talk about the physical effects, there is a large role, for example, fibrin and fibrinogen, which are involved in blood clotting.

Protein food

edible protein following:

• full - those that contain all the essential amino acids for the body;
• defective - those in which there is a partial amino acid composition.

However, the human body is important, and those and others.Especially the first group.Everyone, especially during periods of intensive development (childhood and adolescence), and puberty is to maintain a constant level of protein in itself.After all, we have already discussed the functions that perform these amazing molecules, and we know that almost no process, no biochemical reaction within us can not do without the participation of the polypeptides.

That is why you need to consume each day daily norm of proteins that are contained in the following products:

• egg;
• milk;
• cheese;
• meat and fish;
• beans;
• soybeans;
• beans;
• peanuts;
• wheat;
• oats;
• lentils and others.

If consume daily 0.6 grams of polypeptide per kg of body weight, then the person will never be a lack of these compounds.If a long period of time the body loses essential proteins, the disease occurs, a named amino acid starvation.This leads to severe metabolic disorders and as a result, many other ailments.

proteins in the cell

Inside the smallest structural unit of all living things - cells - are also proteins.And there they perform almost all the functions listed above.Primarily formed cytoskeleton consisting of microtubules, microfilaments.It serves to maintain shape and for transport between inside organelles.For protein molecules, both channels or rails, move various ions, compounds.

important role of proteins embedded in the membrane and located on its surface.Here they receptor and signaling functions are carried out, are taking part in the construction of the membrane itself.They stand on guard, and thus play a protective role.What kinds of proteins in the cell can be attributed to this group?Examples are many, here are several.

1. actin and myosin.
2. elastin.
3. Keratin.
4. Collagen.
5. tubulin.
6. hemoglobin.
7. insulin.
8. Transcobalamin.
9. Transferrin.
10. albumin.

all there are hundreds of different types of proteins that are constantly moving inside each cell.

Types of proteins in the body

They, of course, a huge variety.If you try to somehow divide all existing proteins in the group, it can turn around such a classification.

1. globular proteins.It is those represented by the tertiary structure, that is densely packed globules.Examples of such structures include: immunoglobulins, most of enzymes, many hormones.
2. fibrillar proteins.Represent strictly ordered filaments having correct spatial symmetry.This group includes proteins with primary and secondary structure.For example, keratin, collagen, tropomyosin, fibrinogen.

Generally, you can take as a basis the set of attributes to classify proteins found in the body.United does not exist yet.

Enzymes are biological catalysts

protein nature, which greatly accelerates all occurring biochemical processes.Normal metabolism is simply not possible without these connections.All the processes of synthesis and breakdown, assembly of molecules and their replication, transcription and translation, and others carried out under the influence of a specific type of enzyme.Examples of these molecules can serve:

• oxidoreductase;
• transferase;
• catalase;
• hydrolase;
• isomerase;
• lyase and others.

Today, enzymes are used in everyday life.Thus, in the production of washing powders often used so-called enzyme - this is the biological catalysts.They improve the quality of washing under specified temperature conditions.It is easy to bind with dirt particles and remove them from the tissue surface.

However, due to the nature of the protein enzymes can not tolerate too hot water or neighborhood with alkaline or acidic agents.Indeed, in this case, the denaturation process will occur.