Question

Consider the following statement:
(A) Coenzyme or metal ion that is tightly bound to enzyme protein called a prosthetic group.
(B) A complex catalytic active enzyme with its bound prosthetic group is called apoenzyme.
Select the correct option.
(a) Both (A) and (B) are true
(b) (A) is true but (B) is false
(c) Both (A) and (B) are false
(d) (A) is false but (B) is true

Answer 1

Hint: There are specific types of partner that are required to enzyme to function: one which is organic in nature and binds loosely to the enzyme, like- apo glucose oxidase for glucose sensor and other which are proteinous in nature and bind tightly to the enzyme, like- heme in hemoglobin.

Complete answer:
The enzyme requires a catalyst to increase the rate of chemical reaction, this catalyst is known as cofactor. Co-factor can be an organic group or inorganic group that attaches to the enzyme either covalently or tightly. Organic cofactor can be divided into coenzyme which refers to the functional properties of an enzyme with cofactor and the prosthetic group refers to the structural properties of cofactor with the enzyme. Apoenzyme is an inactive form of the enzyme which can bind to the substrate but cannot transform into the product.

Additional information:
-An enzyme is highly specific to the substrate and plays a major role in carrying out chemical reactions efficiently.
-The enzyme contains a site for the attachment of substrate by weak forces known as active site or the catalytic site or substrate site.
-The enzyme needs helper molecules that can assist in the biochemical transformation of the substrate to the product known as a cofactor.
- Cofactor can be inorganic like- enzyme carbonic anhydrase requires Zn++ and hexokinase requires Mg++ or organic like- Glycogen phosphorylase requires the small organic molecule pyridoxal phosphate.
- The organic cofactor is further divided into a prosthetic group which is a tightly bound organic cofactor like- ‘heme’ prosthetic group tightly bound to ‘globin’ protein and coenzyme which is loosely bound organic cofactor like NAD+ bound to YADH (yeast alcohol dehydrogenase).

So, the correct answer is," (A) is true but (B) is false."

Note:
-Enzyme term is coined by Friedrich Wilhelm Kuhne.
-The active site in the enzyme contains amino acids like aspartic acid, glutamic acid, lysine, serine, etc.
-A coenzyme is chemically changed by the enzymatic reaction in which they participate whereas the prosthetic group can occur only in a separate phase of the enzymatic reaction sequence.