Question

How do the 4 levels of protein folding relate to one another?

Answer 1

Answer:

There are four stages of the protein folding which are classified as primary, secondary, tertiary and quaternary levels. Let us discuss each one by one.

a). Primary level of protein folding

It is the most basic level of protein folding and it consist of only the building blocks of proteins, i.e. it only consist of a sequential chain of amino acids, known as a polypeptide chain. Since it is the most basic form, it can influence all three other stages depending upon the amino acid incorporated and their respective positions in the polypeptide chain.

b). Secondary level of protein folding

This is the second level of protein folding and is a 2D arrangement. It is comprised of different levels of primary polypeptide chains interlinked together to form a 3 dimensional arrangements in form of sheets or helix. Secondary structure may have alpha helix or beta sheets depending upon how primary polypeptide chains interact. As indicated by the name, if polypeptides form a spiral shape interlinked with hydrogen bonds between different amino acids, it is called helix. If the polypeptides sits one above the other with the help of hydrogen bonds, this give a sheet like formation.

c). Tertiary level of protein folding

Third level of the protein folding is produced from the 3 dimensional arrangement of the protein. In this protein structure, certain groups which are not amino acids or polypeptides may get incorporated into the structure. These groups can be different metals such as iron in hemoglobin, copper in carbon monoxide dehydrogenase, copper in ceruloplasmin etc. Chins are held together by the hydrogen bonds.

d). Quaternary level of protein folding

This is the topmost level of protein folding. It consists of multiple polypeptide chains interacting together to form a tertiary protein folding. Let us have some examples of quaternary proteins for better understanding.

i. hemoglobin 4 different polypeptide chains that form one functional protein.

ii. Nicotinic receptor has 5 different polypeptide chain which forms the protein receptor.

iii. Chloride channels in the neurons have 5 polypeptide chains which forms a pore or opening for the passage of chlorine in or out of the neuron.