Proteins are biological polymers with complex structures.They have a high molecular weight and consist of an amino acid prosthetic groups represented by vitamins, lipid and carbohydrate inclusions.Proteins containing carbohydrates, vitamins, lipids or metals, called compound.Only simple proteins composed of amino acids linked together by a peptide bond.
peptides
No matter what structure is a substance monomers of proteins are amino acids.They form a core polypeptide chain, which is then formed fibrillar and globular structure of the protein.When this protein can be synthesized only in living tissue - in plant, bacterial, fungal, and other animal cells.
single organism that can not connect the protein monomers, are viruses and protozoa bacteria.All the other structural proteins are able to form.But what substances are monomers of proteins and how they are formed?This and protein biosynthesis, a polypeptide, and the formation of a complex protein structure of amino acids and their properties, see below.
single monomer molecule protein is any alpha-amino acid.In this protein - a polypeptide chain of linked amino acids.Depending on the number of amino acids involved in its formation are isolated dipeptides (two residues), a tripeptide (3), oligopeptides (containing from 2-10 amino acids) and polypeptides (a plurality of amino acids).
review the structure of proteins
structure of the protein may be a primary, a little more complex - a secondary, more complex - tertiary, and the most difficult - Quaternary.
primary structure - it is a simple circuit which via a peptide bond (CO-NH) connected monomers proteins (amino acids).Secondary structure - is an alpha-helix or beta-sheet.Tertiary - this is even more complicated three-dimensional structure of the protein, which was formed from the secondary due to the formation of covalent, ionic and hydrogen bonding and hydrophobic interactions.
quaternary structure is the most complex and peculiar receptor proteins located on cell membranes.This supramolecular (domain) structure formed as a result of combining several molecules with tertiary structure, supplemented carbohydrate, lipid, or B vitamins.In this case, as in the primary, secondary and tertiary structures of proteins monomers are alpha-amino acids.They are also joined by peptide bonds.The only difference is in the complexity of the structure.
Amino
single monomer protein molecules are alpha-amino acids.There are only 20, and they are hardly the basis of life.The emergence of a peptide bond, protein synthesis was possible.A protein itself then began to perform structure-forming, receptor, enzyme, transport, mediator and other functions.Through this living organism is functioning and able to play.
itself alpha-amino acid is an organic carboxylic acid with an amino group bonded to the alpha-carbon atom.Last situated next to the carboxyl group.Thus monomers of proteins are considered as organic substances which have a terminal carbon atom and bears an amine and a carboxyl group.
compound of amino acids in peptides and proteins
amino acids joined in dimers, trimers and polymers by means of a peptide bond.It is formed by cleavage of hydroxyl (-OH) group from the carboxyl portion of one alpha-amino acid and hydrogen (H) - amino group of another alpha-amino acids.The interaction of water is split off, and the carboxyl-terminal portion is C = O with a free electron about carboxyl carbon residue.In another amino acid residue has (NH) with an available free radical at the nitrogen atom.This allows you to connect the two radicals to form a bond (CONH).It is called a peptide.
variants of alpha-amino acids
Total known 23 alpha-amino acids.They are presented as a list of: glycine, valine, alanine, isoleucine, leucine, glutamate, aspartate, ornithine, threonine, serine, lysine, cystine, cysteine, phenylalanine, methionine, tyrosine, proline, tryptophan, hydroxyproline, arginine, histidine, asparagine andglutamine.Depending on whether they can be synthesized by the human body, these amino acids are divided into the essential and nonessential.
notion of essential and nonessential amino acids
Interchangeable human body can synthesize, whereas essential should come only with food.At the same time, and the essential and nonessential acids are important for protein biosynthesis, because without them, the synthesis can not be completed.Without a single amino acid, even if everyone else present, it is impossible to build the protein that the cell is required to perform its functions.
One mistake at any stage of the biosynthesis - and the protein is unsuitable, because it will not be able to meet the desired structure of the disruption of electron densities and interatomic interactions.Because humans (and other organisms), it is important to consume protein products, which are the essential amino acids.Their absence in the diet leads to a number of disorders of protein metabolism.
The formation of a peptide bond
single monomer proteins are alpha-amino acids.They gradually joined in polypeptide chain, the structure of which is stored in advance in the genetic code of DNA (or RNA if treated bacterial biosynthesis).In this protein - a strict sequence of amino acid residues.This chain is arranged in a certain structure in the cell performs a pre-programmed function.
stage sequence of protein biosynthesis
The formation of the protein consists of a chain of stages: replication region of DNA (or RNA), RNA synthesis information type, its output in the cytoplasm from the nucleus, the compound with the ribosome and the gradual insertion of amino acid residues that are supplied transfer RNA.A substance which is a monomer protein, is involved in the enzymatic cleavage reaction of a hydroxyl group and a hydrogen proton, and then joins the extensible polipetidnoy chain.
thus obtained polypeptide chain, which is already in the cellular endoplasmic reticulum is ordered in a certain predetermined structure and supplemented carbohydrate or lipid moiety when required.This process is called "maturation" of the protein, after which he sent to the cellular transport system to a destination.
functions synthesized proteins
protein monomers are amino acids needed to build their primary structure.Secondary, tertiary and quaternary structure has formed itself, although sometimes also requires the participation of enzymes and other substances.However, they are not the main, though it is imperative that the proteins perform their function.
amino acid that is a monomer protein, can hold the attachment of carbohydrates, metals, or vitamins.Education tertiary or quaternary structure makes it possible to find more places for the location of the inserted groups.This provides a derivative of the protein, which plays a role of the enzyme, receptor, transporter substances into or out of the cell, immunoglobulin structural component of the cell membrane or organelles of muscle protein.
protein formed from amino acids, are the only basis of life.Today, it is believed that life arose just after the appearance of amino acids, due to its polymerization.After all, the intermolecular interactions of proteins and is the beginning of life, including intelligent.All other biochemical processes, including energy, are necessary for the implementation of protein biosynthesis, and as a result, the further continuation of life.
