Question

What is the difference between native protein and denatured proteins?

Answer 1

As we know that protein is a polypeptide with more than hundreds of amino acids having molecular weight higher than that of ten thousand. Proteins can be natural or denatured where a biological activity of a protein is lost due to folding or unfolding of globules and helixes.

Complete answer: We know very well that proteins are high molecular mass complexes and biopolymers of alpha amino acids which are present in all living cells. Proteins occur in every part of the body and they form the fundamental basis of structure and functions of life.
Proteins can be classified on the basis of their structure as primary, secondary, tertiary and quaternary proteins. Primary proteins include one or more than one polypeptide chain arranged linearly. Secondary proteins are those which can exist in alpha-helix and beta-pleated sheets formed due to regular folding of the backbone of the polypeptide chain. Tertiary protein involves further folding of secondary structures of proteins.
Now, a protein can be natural or native which basically means that a protein possesses a particular biological activity and a unique three-dimensional structure. The native proteins chiefly exist in primary, secondary, tertiary and quaternary structures.
But when this native protein is subjected to various changes under different provided conditions like pH change, the secondary and tertiary structure of protein are destroyed but the primary structures remain intact and thus a protein loses its natural biological activity resulting in a denatured protein.
For instance: the coagulation of egg white on boiling or curing of milk which is caused due to the formation of lactic acid by the bacteria present in milk.

Note: Always remember that when the chemical and physical properties of native protein are changed, the biological activity of a protein is lost. A protein can be globular and fibrous based on their molecular mass where fibrous protein like keratin are formed due to parallel sun of polypeptide chains and globular proteins like insulin are formed when polypeptide chains coils around in a spherical shape.