Proteins are natural organic compounds that have a high molecular weight structure. The molecule of these substances is a non-branching polymer. Proteins are built from 20 amino acids. They represent the structural minimal unit of the molecule - the monomer. All components of the protein are interconnected by a polypeptide, in another way, a urea bond, in fairly long chains. In this case, the molecular weight can be from several thousand to millions of atomic particles.
What can be protein
To determine the basic functions of a protein, it is worth understanding the structure of such substances. At the moment, there are two varieties of this component important for humans: fibrillar and globular. They are distinguished 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. Moreover, the molecule of such a protein has a spherical shape. This good solubility can easily be explained by the location of the charged amino acid residues, which are surrounded by a hydration shell, on the surface of the globule. This is what provides such good contact with various solvents. It is worth noting that the group of globular components includes all enzymes, as well as almost 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 excipients. Fibrillar proteins are not soluble in saline solutions, nor in ordinary water. Their molecules are located in parallel in polypeptide chains. Such substances are involved in the formation of some structural elements of connective tissues. These are elastins, keratins, collagen.
A special group consists of complex proteins, which consist not only of amino acids, but also of nucleic acids, carbohydrates and other substances. All of these components play a special role. Of particular importance is the catalytic function of proteins. In addition, substances of a similar plan are respiratory pigments, hormones, as well as reliable protection for any organism. Protein biosynthesis is carried out on ribosomes. This process is determined upon translation by a nucleic acid code.
The catalytic function of proteins
The catalysis of a variety of chemicals is the most important function of proteins. Similar processes are carried out by enzymes. These are proteins that have specific catalytic properties. Each of these substances can carry out one or several similar reactions. The enzymes catalyze the process of splitting complex molecules, as well as their synthesis. Otherwise, these reactions are called catabolism and anabolism. The catalytic function of proteins also implies DNA repair and replication, as well as matrix RNA synthesis.
What is catalysis
By 2013, scientists had identified just over 5 thousand enzymes. Such substances can affect the course of almost any biochemical reaction. To make the catalytic function of proteins more understandable, it is worth understanding what catalysis is. From Greek, this concept translates as "termination." Catalysis is a change in the rate of any chemical reaction. This happens under the influence of certain compounds. Enzymes perform the catalytic function of proteins. Examples of this phenomenon are found in everyday life constantly. Just a person does not notice this.
Catalytic Function Example
To understand how enzymes work, it’s worth considering a few examples. So, what is the catalytic function of proteins. Examples:
- During photosynthesis, ribulose bisphosphate carboxylase catalyses the fixation of CO 2 .
- Hydrogen peroxide breaks down to oxygen and water.
- DNA synthesizes DNA polymerase.
- Amylase is capable of breaking down starch to maltose.
- Carbonic acid degradation: 2 + 2 3 + + .
The catalytic function of proteins is to accelerate any chemical transformations. Such reactions include synthesis, decay of substances, transfer of individual atoms or electrons from one component to another.
Transport function
The vital activity of any cell should be supported by various substances, which are for them not only building material, but also a kind of energy. The biological functions of proteins include transport. It is these components that supply all important substances to cells, because membranes are built of several layers of lipids. It is here that various proteins are located. At the same time, the hydrophilic sites are all concentrated on the surface, and the tails are in the thickness of the membranes. This structure does not allow the penetration of very important substances into the cells - alkali metal ions, amino acids and sugars. Proteins carry all of these components into cells for their nutrition. For example, hemoglobin transports oxygen.
Receptor
The main functions of the protein provide not only the nutrition of cells of living organisms, but also help to recognize signals that come from the environment and neighboring cells. The most striking example of this phenomenon is acetylcholine receptors, which is located on the membrane near interneuronal contacts. The process itself is very important. Proteins perform a receptor function, their interaction with acetylcholine manifests itself in a specific way. As a result, a signal is transmitted inside the cell. However, after some time, the neurotransmitter must be removed. Only in this case the cell will be able to receive a new signal. It is this function that one of the enzymes, acetylcholnesterase, which cleaves to choline and hydrolysis of acetylcholine acetate.
Protective
The immune system of any living creature is able to respond to the appearance of foreign particles in the body. In this case, the protective function of the protein is triggered. The body produces a large number of lymphocytes, which are capable of harming pathogenic bacteria, macromolecules, cancer cells and more. One of the groups of these substances produces specific proteins - immunoglobulins. These substances are released into 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 by humans. Some substances are mostly structurally significant. Such proteins provide the 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 a living organism.
It is worth noting that in mammals, collagen is approximately 25% of the total protein mass. The synthesis of this component occurs in fibroblasts. These are the main cells of any connective tissue. Initially, collagen is formed. This substance is a precursor and undergoes chemical treatment, which consists in the oxidation of proline residues to hydroxyproline, as well as lysine residues to hydroxylin. Collagen is formed in the form of three peptide chains twisted into a spiral.
These are not all the functions of proteins. Biology is a rather complex science that allows you to identify and recognize many phenomena that occur in the human body. Each protein function plays a special role. So, in elastic tissues, for example in the lungs, walls of blood vessels and 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 converted into mechanical work. In this case, the functions of the protein in the cell are performed by myosin and actin. Each of them has its own characteristics.
Myosin has an extraordinary structure. This protein consists of a filamentous enough part - the tail, as well as 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 thousand, as well as 4 chains, the molecular weight of which is only 20 thousand.
Actin is a globular protein that has the ability to polymerize. In this case, the substance forms a rather long structure, which is usually called F-actin. Only in this state can the component interact normally with myosin.
Examples of basic protein functions
Every second in the cells of a living organism all kinds of processes take place that would not have been possible without proteins. An example of the receptor function of such substances is the message to the adrenoreceptor cells about the adrenaline addition. Under the influence of light, rhodopsin decomposes. A similar phenomenon triggers a reaction and excites the wand.
As for the structural function, the best example in this case is the effect of collagen. This substance gives connective tissue more elasticity.
An example of a transport function is the transport of oxygen by hemoglobin throughout a living organism.
Finally
These are all the basic biological functions of proteins. Each of them is very important for a living organism. Moreover, 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.