Tandem mass spectrometry is an advanced technique of structural elucidation of proteins. In case of portions analysis, the proteins are firstly digested by protease enzymes and then the mass spectrometer estimates the probable structure of protein by passing a beam of electrons through it. This technique is based upon the principle of ionization of the biomolecules and them the arrangement of these molecules on bases of their mass to charge ratio. The complete data is used to create a 3D structure of protein on the computer screen and it can also detect the domains and the structural flexibility of the protein molecule. Nuclear overhauser effect is principle of this technique in which the spinning ability of components of molecule (amino acids in case of proteins) is used to calculate the distances among them. Nuclear Magnetic Resonance Spectroscopy (NMR Spectroscopy)īased upon the magnetic properties of atomic nuclei of certain biomolecules, this technique is useful to detect the 3D structure of proteins but limited to proteins of 35kDa. The process is repeated several times to detect the other aminao acids of protin molecule. Then under at acidic pH, this terminal aminao acid is cleaved to yield a thiozolinone product that is later extracted and then the technique of electrophoresis or chromatography is performed to identify that amino acid. The reaction results in phenythiocarbamoyl product. In this technique, reaction of phenyl isothiocyanate with the N-terminal amino acid of protein molecule under alkaline conditions. The whole data is used by computer to estimate the most probable location of each component of the protein molecule and thus creates a 3D structure of protein on screen. An x-ray source is used to aim high power x-rays on the protein molecule that scatters the rays in various directions.Ī detector detects these scatted x-rays of different wave lengths and intensities. The principle of this technique is thatthe structure of protein is detected by the growth of crystal/structure of protein. This technique is useful for detection of 3D structure of protein. Here are some methods used for structural elucidation of proteins: 1. Methods Used For Structural Elucidation of Proteins Quaternary structure: A three dimensional structure formed of multiple subunits held together by disulphide bridges and non-covalent interactions is quaternary structure.Tertiary Structure: The α-helix and β-sheets further fold together to form a globular structure of protein that is tertiary structure and held together by disulphide bridges as well.Secondary Structure: These structures are formed by the coiling and folding of primary structure and these structures are α-helix and β-sheets in which the folding is held together by hydrogen bonds also.Primary Structure: This structure is simply the linear arrangenment of amino acids that are held together by peptide and covalent bonds. There are four main structures of proteins: Also, for the type of bonding among them. Proteins can have different structure depending upon the type of amino acids from which they are formed. Proteins are essential part of living systems as they are involved in structure and function of cell.Īll the proteins are composed of amino acid molecules joined together by peptide linkage. Proteins are nitrogenous organic compound that are polymers of large numbers of amino acid units joined together by peptide bonds.
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