Protein biosynthesis occurs in all organs, tissues and cells.The largest amount of protein synthesized in the liver.Ribosomes perform protein biosynthesis.Chemically ribosomes - nucleoproteins composed of RNA (50-65%) and protein (35-50%).Ribonucleic acids are components of granular endoplasmic reticulum, where there biosynthesis and move the synthesized protein molecules.
ribosomes in the cell are in the form of clusters of 3 to 100 units - policy (polyribosome).Ribosomes are usually connected to each other kind of thread, visible under an electron microscope - and RNA.
Each ribosome to synthesize their own Odin polypeptide chain, the group - and some of these chains of protein molecules.
stages of protein biosynthesis
Activation of amino acids.In hyaloplasm of interstitial fluid by diffusion, osmosis or active transport of the amino acids act.Each type of amino and imino acids interacts with individual enzymes - aminoatsilsintetazoy.Reactions activated cations magnesium, manganese, cobalt.There is an activated amino acid.
Protein biosynthesis (second stage) - and interconnection activated amino acid with tRNA.Activated amino acids (aminoacyl adenylate) using enzymes transferred to the t-RNA of the cytoplasm.The process is catalyzed by aminoacyl tRNA synthetase.Amino acid residue is coupled with the hydroxyl of the carboxyl group of the second atom Carbo ribose nucleotide tRNA.
Protein biosynthesis (third stage) - transportation complex of the activated amino acid to the tRNA to the ribosome of the cell.An amino acid linked to the tRNA, is transferred from hyaloplasm on ribosomes.The process is catalyzed by specific enzymes, in which the body is not less than 20. Some amino acids are transported several tRNA (e.g., valine and leucine - three tRNA).This process uses the energy of ATP and GTP.The fourth stage is characterized by the biosynthesis of the binding of aminoacyl-tRNA complex with mRNA - ribosome.Aminoacyl-tRNA, going to the ribosome interacts with mRNA.Each tRNA has a section consisting of three nucleotides - anticodon.The mRNA corresponds to section three nucleotides - the codon.Each codon correspond to the tRNA anticodon and one amino acid.During the biosynthesis of ribosomes to join as aminoacyl-tRNA the amino acids, which are then in the manner determined by the placement of codons in mRNA formed in the polypeptide chain.
next stage of protein biosynthesis - is the initiation of the polypeptide chain.After two neighboring aminoacyl-tRNA anticodon joined their codon and RNA, the conditions for the synthesis of a polypeptide chain.Formed peptide bond.These processes are catalyzed peptide synthetases, activated cations Mg and initiation factors of protein nature F1, F2, F3.The source of the chemical energy is guanozintrifosfatnaya acid.
Termination of the polypeptide chain.The ribosome, which was synthesized on the surface of the polypeptide chain, the chain reaches the end of mRNA, as the "jumps" out of it.To the opposite end of the mRNA at its new location joins the ribosome, which synthesizes another polypeptide molecule.Polypeptide chain detaches from the ribosome and is excreted in hyaloplasm.This reaction is carried out using a specific release factor (factor R), which is connected with the ribosome and facilitates the hydrolysis of the ether linkage between the polypeptide and tRNA.
hyaloplasm The polypeptide chains are formed from simple and complex proteins.Formed secondary, tertiary and in many cases - the quaternary structure of the protein molecule.Thus the proteins are in the cell.
