In a large protein like haemoglobin, or in case of an enzyme, the molecule undergoes further folding and coiling to attain functional conformation. This is termed the Tertiary Structure. The coils and folds of the protein molecule are so arranged as to hide non-polar amino acid side chains inside and expose the polar side chains. The 3-dimensional conformation of a protein brings distant amino acid side chains closer. The active sites of proteins such as enzymes are thus formed. The conformation of proteins is easily changed by pH, temperature and chemical substances and hence the function of proteins is liable and subject to regulation.
In tertiary structure, the polypeptide chain having secondary structure is twisted and folded to produce a stable, three dimensional structure, which may be maintained by three types of bonds e.g. Ionic bond, Hydrogen bond and Disulphide bond. Disulphide bond arises between two amino acids containing sulphur as cysteine. This bond is strongest of all the bonds. In a large protein like haemoglobin, or in case of an enzyme, the molecule undergoes further folding and coiling to attain functional conformation. This is termed the Tertiary Structure. The coils and folds of the protein molecule are so arranged as to hide non-polar amino acid side chains inside and expose the polar side chains. The 3-dimensional conformation of a protein brings distant amino acid side chains closer. The active sites of proteins such as enzymes are thus formed.