Proteins are polymers of amino acids and are the most abundant organic molecules of the living system constituting about 50% of the cellular dry weight.
Amino acids are organic compounds containing two functional groups i.e. amino (-NH2
) group and carboxyl (-COOH) group along with a side chain specific to each amino acid.
STRUCTURE OF AMINO ACIDS:
Chemically, an amino acid consists of four components
- Carboxylic group (-COOH), which is basic in nature.
- Amino group (-NH2), which is acidic in nature.
- R side chain which is specific for each amino acid and accounts for the different types of amino acids.
- Hydrogen atom linked to the central carbon atom.
If both the carboxyl group and amino groups are attached to the same carbon, the amino acid is termed as α amino acid.
- There are almost 400 identified amino acids occurring in nature however, only 20 are involved in protein formation in living organisms.
- These 20 proteins arrange in various combinations to produce different types of proteins in living organism.
The adjacent amino acids in a polypeptide protein chain are linked together via peptide bonds.