Biomolecules-proteins

Proteins are the most abundant bio molecules of the living system.All proteins are polymers of

Structure of proteins: Two amino acids are linked together by peptide linkage.It is formed between -COOH group and the -NH2 group.

A polypeptide( many amino acids linked) with more than hundred amino acids joined and having molecular mass higher than 10,000 u is called a protein.

Classification of structure of proteins:

     1)primary structure: Each amino acid in a protein is linked with another in a particular        sequence and this is primary structure of that  protein.Any change in this structure creates a different protein.    

    2)secondary structure: is the shape in which polypeptide chains exist..

    3)Tertiary structure:Represents the irregular folding of the secondary structure.
        Gives rise to two shapes of proteins: 
                   Fibrous-  polypeptide chains run in parallel and are held together by hydrogen,di-sulphide bonds.generally insoluble in water. examples: keratin, myosin.

                   Globular- chains of polypeptide coil around to give a spherical shape usually     soluble in water.examples:insulin,albumin.

4)Quaternary structure: Refers to the spatial arrangement of two or more polypeptide chains grouped together(also called sub units).