Hint: The structures of building blocks of enzymes are made up of amino acids. They have a different level of structures like primary, secondary, tertiary, and quaternary. Chemically all enzymes are globular proteins. Amino acids have acid groups and amine groups.
Complete step by step answer:
All biological reactions are catalyzed by a special catalyst called enzymes. The enzymes are defined as a biological catalyst or simply biocatalyst. An enzyme facilitates a biochemical reaction by providing alternate lower activation energy pathways thereby increases the rate of the reaction.
Chemically all enzymes are globular proteins. However, some enzymes are also associated with some non-protein components called co-factor for their activity. These cofactors are of two types:
(a)- Inorganic ions such as zinc, magnesium, iron, copper, cobalt, etc.
(b)- Organic molecules: These are of two types:
(i)- The coenzyme is small organic molecules that are only loosely held to the protein and can be easily separated by dialysis. These are usually derived from vitamins such as thiamine, riboflavin, niacin, etc.
(ii)- Prosthetic groups are also an organic group which is tightly held to the protein by covalent bond but can be easily separated only by careful hydrolysis. Most of these are derived from vitamins such as biotin.
Regardless of the nature of the cofactor, the protein-cofactor complex is called the holoenzyme while the inactive protein part left after the removal of the cofactor is called the apoenzyme. Thus,
Catalytic action of enzyme: This works as a lock and key mechanism.
The first function of an enzyme is to hold the substrate molecule for a chemical reaction.
The second function of the enzyme is to provide a functional group which will attack the substrate to carry out the chemical reaction.
The enzyme has a specific action with a single substrate and it is explained with lock and key mechanism. In this, lock is the enzyme and key is the substrate. Only the correctly sized substrate will fit into the enzyme like lock and key.
This analogy was proposed first in 1894 by Emil Fischer.
Hence, the correct answer is an option (b)- protein with a specific structure.
Note: You may get confused between edible protein and protein with specific structure because the main constituents are protein but to be specified they have special structures. Don’t get confused between holoenzyme and apoenzyme.