![]() The spatial arrangement of these polypeptide chains with respect to each other is know as quaternary structure. ![]() (4) Quaternary structure : Two or more amino acids chains or polypeptide chains forms complex protein. The polypeptide in tertiary strcuture held by disulphide or hydrogen bonds or van der Waals forces or electrostatic forces of attraction. This is the website for The Protein Coil Library, a library of protein structure fragments derived from the Protein Data Bank (PDB). (3) Tertiary structure : The secondary structure on folding gives rise to molecular shapes i.e., fibrous and globular. ![]() The contraction results in a pleated sheets called β-pleated sheet. The poly peptide chains are stretched out resulting in a flat sheet. (ii) β - pleated structure: The polypeptide chain lie side by side and are held together by intermolecular hydrogen bonding. secondary structure and 7276 of protein exists in aperiodic form, the degree of stabilization by helix and structure is very low 49, 50. The hydrogen bonding between − ∣ C = O and -NH groups occurs in different parts of the same chain resulting in folding of polypeptide chain. (i) α-Helix structure : In β- Helix structure a poly peptide chain gets coiled by twisting into right handed spiral known as α -helix. There are two differet types of structures α helix and β - pleated sheets. (2) Secondary structure : When long amino acid chain is coiled, looped or folded, it gives particular shape to a protein molecule, it is referred as secondary structure. Each protein has amino acids linked with each other in a specific sequence and this sequence of amino acids is termet as primary structure.Īny change in the primary structures creates different protein molecule. (1) Primary structure : In primary structure, proteins contain polypeptide chain. ![]() The evolution of secondary structures during molecular dynamics. The structure and shape of proteins can be studied at four different levels called primary, secondary, tertiary and quaternary.Įach level is more complex than the previous one. The investigation on the types of secondary structure (SS) of a protein is important. ![]()
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