The catalytic function of proteins: examples. Basic functions of proteins

Proteins are natural organic compounds that have a high molecular weight structure. The molecule of these substances is an unbranched polymer. Proteins are constructed of 20 amino acids. They represent the structural minimum unit of the molecule - monomer. All the components of the protein are joined together by a polypeptide, in a different way, carbamide, linking into sufficiently long chains. In this case, the molecular weight can range from several thousand to millions of atomic particles.

What can be a protein

To determine the basic functions of protein, it is worthwhile to understand the structure of such substances. At the moment, there are two varieties of this important for human component: fibrillar and globular. Distinguish them mainly due to the difference in the structure of the protein molecule.

The globular substance is perfectly soluble not only in water, but also in saline solutions. In this case, the molecule of such a protein has a spherical shape. Such good solubility can easily be explained by the arrangement of charged amino acid residues, which are surrounded by a hydrated shell, on the surface of the globule. This is what ensures such good contacts with various solvents. It should be noted that the group of globular components includes all enzymes, as well as virtually all biologically active proteins.

As for fibrillar substances, their molecules have a fibrous structure. The catalytic function of proteins is very important. Therefore, it is difficult to imagine its implementation without auxiliary substances. Fibrillar proteins do not dissolve either in saline solutions or in ordinary water. Their molecules are located in parallel in polypeptide chains. Such substances are involved in the formation of certain structural elements of connective tissues. These are elastins, keratins, collagens.

A special group consists of complex proteins, which consist not only of amino acids, but also of nucleic acids, carbohydrates and other substances. All these components play a special role. Of particular importance is the catalytic function of proteins. In addition, substances of this kind are breathing pigments, hormones, and also a reliable protection for any organism. Biosynthesis of protein is carried out on ribosomes. This process is determined by translation with the code of nucleic acids.

The catalytic function of proteins

The catalysis of a variety of chemicals is the most important function of proteins. Such processes are carried out by enzymes. These are proteins that have catalytic specific properties. Each of such substances can carry out one or several similar reactions. The enzymes are catalyzed by the process of cleavage of complex molecules, as well as their synthesis. In another way these reactions are called catabolism and anabolism. The catalytic function of proteins also implies the repair and replication of DNA, as well as the matrix synthesis of RNA.

What is catalysis

Already by 2013, scientists have identified slightly more than 5 thousand enzymes. Such substances can influence the course of almost any biochemical reactions. To make the catalytic function of proteins more understandable, it is worth investigating what is catalysis. From the Greek language this concept is translated as "termination". Catalysis is a change in the rate of any chemical reaction. This occurs under the influence of certain compounds. Enzymes perform the catalytic function of proteins. Examples of this phenomenon are found in everyday life all the time. Just a person does not notice.

An example of a catalytic function

To understand how enzymes work, it is worthwhile to consider several examples. So, what is the catalytic function of proteins. Examples:

1. In photosynthesis, ribulosebisphosphate carboxylase catalyzes the fixation of CO ₂ .
2. Hydrogen peroxide is split to oxygen and water.
3. DNA synthesizes DNA polymerase.
4. Amylase is able to break up starch before maltose.
5. Degradation of carbonic acid: CO ₂ + H ₂ O HCO ₃ + H ⁺ .

The catalytic function of proteins is to accelerate any chemical transformation. Such reactions include synthesis, decay of substances, transfer of individual atoms or electrons from one component to another.

Transport function

The life activity of any cell must be supported by various substances, which are for them not only a building material, but also a kind of energy. Biological functions of proteins include transport. It is these components that supply all important substances to the cells, because the membranes are built of several layers of lipids. It is here that there are various proteins. In this case, the hydrophilic areas are all concentrated on the surface, and the tails are in the thickness of the membranes. This structure does not allow penetrating into cells of very important substances - alkali metal ions, amino acids and sugars. Proteins transfer all these components into cells for their nutrition. For example, hemoglobin transports oxygen.

Receptor

The basic functions of protein provide not only nutrition of cells of living organisms, but also help to recognize signals that come from the external environment and neighboring cells. The most striking example of this phenomenon is the acetylcholine receptors, which is located on the membrane near the inter-neuron contacts. The process itself is very important. Proteins perform a receptor function, their interaction with acetylcholine is manifested in a specific way. As a result, a signal is transmitted inside the cell. However, after a while, the neurotransmitter must necessarily be removed. Only in this case will the cell be able to receive a new signal. This function is performed by one of the enzymes - acetyl holotnasterase, which performs cleavage to choline and hydrolyzacetylcholine acetate.

Protective

The immune system of any living being is capable of responding to the appearance of foreign particles in the body. In this case, the protective function of the protein works. The body produces a large number of lymphocytes, which are capable of damaging pathogenic bacteria, macromolecules, cancer cells and so on. One of the groups of these substances produces the production of special proteins - immunoglobulins. There is a selection of these substances in the circulatory system. Immunoglobulins recognize foreign particles and form a highly specific complex of a certain stage of destruction. This is the protective function of the protein.

Structural

The functions of the protein in the cell proceed unnoticed for a person. Some substances are mostly of structural importance. Such proteins provide mechanical strength of individual tissues in organisms. First of all, it is collagen. This is the main component of the extracellular matrix of all connective tissues in the living body.

It is worth noting that in mammals the collagen is about 25% of the total protein mass. Synthesis of this component occurs in fibroblasts. These are the basic cells of any connective tissue. Procollagen is initially formed. This substance is a precursor and undergoes chemical treatment, which consists in the oxidation of proline residues to hydroxyproline, as well as to the hydroxylin of lysine residues. Collagen is formed in the form of three peptide chains, twisted into a spiral.

These are not all functions of proteins. Biology is a rather complex science that allows you to identify and recognize a variety of phenomena occurring in the human body. Each protein function plays a special role. So, in the elastic tissues, for example in the lungs, the walls of the blood vessels and the skin, there is elastin. This protein is able to stretch, and then return to its original form.

Motor proteins

Muscle contractions are a process in which the energy stored in ATP molecules in the form of pyrophosphate macroergic bonds is transformed into mechanical work. In this case, protein functions in the cell are performed by myosin and actin. Each of them has its own characteristics.

Myosin has an unusual structure. This protein consists of a tail-shaped thread-like length, and also of several globular heads. Myosin is released, usually in the form of a hexamer. This component is formed by several completely identical polypeptide chains, each of which has a molecular weight of 200,000, and also 4 chains, whose molecular weight is only 20,000.

Actin is a globular protein that has the ability to polymerize. In this case, the substance forms a sufficiently long structure, which is commonly called F-actin. Only in this state can the component normally interact with myosin.

Examples of the basic functions of proteins

Every second in the cells of a living organism, all sorts of processes take place that would not have been possible without proteins. An example of the receptor function of such substances can serve as a message to adrenoreceptor cells about adrenaline adherence. Under the influence of light, the decomposition of rhodopsin occurs. A similar phenomenon triggers a reaction and stimulates the wand.

As for the structural function, the best example in this case can be the action of collagen. This substance gives the connective tissues more elasticity.

An example of a transport function is the transfer of hemoglobin oxygen throughout the living organism.

Finally

These are all the basic biological functions of proteins. Each of them is very important for a living organism. In this case, a certain function is performed by the corresponding protein. The absence of such components can lead to disruption of certain organs and systems in the body.