Q.7 Match List-I with List-II
| List-I | List-II |
|---|---|
| Enzyme | Type of reaction catalyzed |
| (A) Alcohol Dehydrogenase | (I) Bond formation coupled to ATP hydrolysis |
| (B) Trypsin | (II) Transfer of electrons |
| (C) Hexokinase | (III) Hydrolysis reactions |
| (D) Pyruvate carboxylase | (IV) Transfer of functional groups |
Choose the correct answer from the options given below:
- (A) – (I), (B) – (II), (C) – (III), (D) – (IV)
- (A) – (I), (B) – (III), (C) – (III), (D) – (IV)
- (A) – (II), (B) – (III), (C) – (IV), (D) – (I)
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(A) – (II), (B) – (III), (C) – (I), (D) – (IV)
The correct matching for this enzyme-reaction question is, as it accurately pairs each enzyme with its primary catalytic mechanism.
Question Breakdown
This matching question from exams like GATE Life Sciences tests enzyme classification by reaction type, focusing on oxidoreductases, hydrolases, transferases, and ligases.
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Option 1: (A)–(I), (B)–(II), (C)–(III), (D)–(IV) Incorrect—misassigns Alcohol Dehydrogenase (electron transfer) to bond formation and Hexokinase (ATP-coupled) to hydrolysis.
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Option 2: (A)–(I), (B)–(III), (C)–(III), (D)–(IV) Incorrect—wrongly places Alcohol Dehydrogenase under bond formation (it’s oxidation-reduction) and duplicates hydrolysis for both Trypsin and Hexokinase.
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Option 3: (A)–(II), (B)–(III), (C)–(I), (D)–(IV) Correct—Alcohol Dehydrogenase transfers electrons (II); Trypsin hydrolyzes peptide bonds (III); Hexokinase forms bonds via ATP hydrolysis (I); Pyruvate carboxylase transfers carboxyl groups (IV).
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Option 4: (A)–(III), (B)–(IV), (C)–(I), (D)–(II) Incorrect—confuses Alcohol Dehydrogenase (not hydrolysis), Trypsin (not group transfer), and Pyruvate carboxylase (not electron transfer).(A) – (III), (B) – (IV), (C) – (I), (D) – (II)
Introduction to Enzyme Matching List-I List-II
Enzyme matching List-I List-II questions assess classification of enzymes like Alcohol Dehydrogenase, Trypsin, Hexokinase, and Pyruvate Carboxylase by reaction types such as electron transfer, hydrolysis, ATP-coupled bond formation, and group transfer. These are staples in GATE Life Sciences PYQs, linking biochemistry to metabolic pathways.
Alcohol Dehydrogenase Reaction
Alcohol Dehydrogenase (A) catalyzes oxidation of alcohols to aldehydes/ketones, transferring hydride (electrons) from substrate to NAD⁺, forming NADH—classified as electron transfer (II). Zinc and residues like His-51 facilitate deprotonation and hydride shift in this reversible oxidoreductase reaction.
Trypsin Hydrolysis Mechanism
Trypsin (B), a serine protease, performs hydrolysis reactions (III) by cleaving peptide bonds after lysine/arginine via nucleophilic attack by Ser-195 in its catalytic triad. This endopeptidase action is pH-dependent and inhibited by SERPINs.
Hexokinase Bond Formation
Hexokinase (C) transfers phosphate from ATP to glucose, forming glucose-6-phosphate—a bond formation coupled to ATP hydrolysis (I), typical of kinases (ligases in some classifications). This commits glucose to glycolysis with high substrate affinity.
Pyruvate Carboxylase Group Transfer
Pyruvate Carboxylase (D) biotin-dependently transfers a carboxyl group from CO₂ to pyruvate, forming oxaloacetate for gluconeogenesis—anaplerosis via group transfer (IV), allosterically activated by acetyl-CoA.
Enzyme (List-I) Reaction Type (List-II) Key Cofactor/Feature Biological Role (A) Alcohol Dehydrogenase (II) Electron transfer NAD⁺, Zn²⁺ Alcohol metabolism (B) Trypsin (III) Hydrolysis Catalytic triad Protein digestion (C) Hexokinase (I) ATP hydrolysis bond formation ATP, Mg²⁺ Glycolysis entry (D) Pyruvate Carboxylase (IV) Functional group transfer Biotin Gluconeogenesis -
