Which of the following statements about the naming of enzymes is correct?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → Enzymes are generally named after the compound upon which they work, as in maltase, the enzyme that catalyses hydrolysis of maltose into glucose.
Most enzymes take their name from the compound or class of compounds they act on: the enzyme that hydrolyses maltose is maltase. Only sometimes is an enzyme named after the reaction it is used in; oxidoreductases, which catalyse an oxidation together with a reduction, are named in this way. In both cases the name ends in -ase.
Why the other options are incorrect
Option (1) Enzymes are generally named after the reaction in which they are used, as in maltase, the enzyme that catalyses hydrolysis of maltose into glucose. — Incorrect. Naming after the reaction is the exception, not the general rule; and maltase is named after its substrate, maltose, not after a reaction.
Option (2) Enzymes are generally named after the compound upon which they work, as in oxidoreductases, the enzymes that catalyse the oxidation of one substrate with simultaneous reduction of another substrate. — Incorrect. The general rule is right, but oxidoreductases are an example of naming after the reaction, not after a compound.
Option (3) Enzymes are generally named after the compound upon which they work, and the ending of the name of an enzyme is -ose, as in maltose for the enzyme that hydrolyses maltose. — Incorrect. The general rule is right, but the name of an enzyme ends in -ase, not -ose; the enzyme for maltose is maltase, while maltose itself is the sugar.
NCERT (2026-27 edition):
10.3 Enzymes – “They are generally named after the compound or class of compounds upon which they work. For example, the enzyme that catalyses hydrolysis of maltose into glucose is named as maltase.”
“Sometimes enzymes are also named after the reaction, where they are used. For example, the enzymes which catalyse the oxidation of one substrate with simultaneous reduction of another substrate are named as oxidoreductase enzymes. The ending of the name of an enzyme is -ase.”