Question

What is meant by tertiary structure of proteins?

Answer 1

Hint:- Proteins are polymers of amino acids. These are the most important and abundant intracellular organic molecules. The protein structure is described at four levels- primary, secondary, tertiary and quaternary.

Complete step-by-step solution:-
- Primary structure is the basic structure of protein and include number and sequence of amino acids in
each polypeptide. It is a linear chain with a C-terminal end and N-terminal end.
- In the secondary structure the thread of the primary structure is folded in the form of alpha-helix. It is
stabilized by hydrogen bonds between oxygen of the carboxylic group of one amino acid and NH group
of the next amino acid.
- The tertiary structure of proteins consists of polypeptide chains folded to form a three-dimensional
globular structure. They have foldings of various types to form a hollow sphere, rods, or fibers. It is
stabilized by various bonds like an ionic bond, hydrophobic bond, hydrogen bond, and covalent
interactions. It is the most important structure of protein for all biological activities. For example all
enzymatic proteins and myoglobins.
- In a quaternary structure, there is an assembly of more than one polypeptide or subunits. Thus, the
individual polypeptide or subunit are arranged with respect to one another, for example, haemoglobin is
a form of two alpha chains and two beta chains. Lactic acid dehydrogenase is another example.

Note:- So proteins are formed by the various permutations and combinations of the amino acids and thus each protein is different from other. Tertiary structure of the protein is considered the active and functional structure of the protein.