conformation (structure) of the peptide chain is ordered and unique to each protein.In special circumstances there is a rupture of a large number of links, which stabilized the spatial structure of the molecule compounds.As a result, the gap is completely entire molecule (or a substantial portion thereof) takes the form of random coil.This process is called 'denaturation'.This change can trigger heat from sixty to eighty degrees.Thus, each molecule, the resulting gap may differ in conformation from the others.
protein denaturation occurs under the influence of any agents capable of destroying non-covalent bonds.This process may occur under alkaline or acidic conditions, the surface of the phase section, under the influence of certain organic compounds (phenols, alcohols and others).Denaturation of the protein may occur under the influence of guanidinium chloride or urea.These agents form weak bonds (hydrophobic, ionic, hydrogen) with carbonyl or amino groups of the peptide backbone with a number of groups of amino acid residues, replacing the existing protein own hydrogen bonds within the molecule.As a result, a change occurs in the secondary and tertiary structure.
Resistance to denaturing agents depends largely on the presence of the protein molecule compounds disulfide bonds.Trypsin inhibitor has three connection S - S. Provided recovery protein denaturation occurs without other influences.If subsequently placed compound conditions, where oxidation is carried cysteine SH-groups and the formation of disulfide bonds, the initial conformation restored.The presence of even a single disulfide bond significantly increases the stability of the spatial structure.
Denaturation of protein, usually accompanied by a decrease in solubility.Along with this often forms a precipitate.There he is in the form of "coagulated protein."At high concentrations of the compounds in the solution, the "phasing" undergoes the entire solution, as, for example, it happens when boiling eggs.When denaturing protein loses its biological activity.On this principle, the use of carbolic acid (phenol aqueous solution) as an antiseptic agent.
Instability of the spatial structure, a high probability of failure under the influence of various agents significantly impede the isolation and study of protein.It is also created certain problems when using the compounds in medicine and industry.If
protein denaturation was carried out by exposure to high temperatures, the slow cooling under certain conditions the process renativatsii - restoration of the native (original) conformation.This fact shows that the laying of the peptide chain is in accordance with the primary structure.
Formation native conformation (the original location) is a spontaneous process.In other words, this arrangement corresponds to the minimum amount of free energy contained in a molecule.Possible resulting conclude that the spatial structure of the compound is encoded in the amino acid sequence in the peptide chain.This in turn means that all polypeptides related alternation of amino acids (e.g., mioglobinovye peptide chains) will receive an identical conformation.
proteins may have significant differences in the primary structure, even if little or absolutely identical in conformation.
