Polymer structure
The size and shape of Polymers are intimately connected to their properties. Generally the shape of both natural and synthetic polymers are described on the basis of the four level of structure.
1) Primary Structure
The primary structure of polymers describe the precise sequence of the polymer chain. For example primary protein(a polymer of amino acids) structure is a sequence of amino acids.
In polymers such as proteins, polysaccharides and nucleic acid, a general unit is repeated in the sequence called repeating structural unit. The repeating structural units of some polymers are given below.
2) Secondary structure
The secondary structure of polymers describe the molecular shape or conformation of polymer chain. The secondary protein structure occurs when the sequence of amino acids are linked by hydrogen bonds. For linear polymer the shape approaches a helical or sheet arrangement depending on the nature of polymer. The helical arrangement and sheet arrangement are shown below.
3) Tertiary structure
In tertiary structure three dimensional folding occurs due to side chain interactions. The tertiary protein structure occurs when certain attractions are present between alpha helices and pleated sheets.
4) Quaternary structure
The quaternary structure of polymers describe the overall folding of tertiary structures. The tertiary structure may be different or similar. The quaternary protein structure consist of more than one amino acid chain.
Comments
Post a Comment