Enzyme classification: Which activities are catalyzed by transferases (group-transfer enzymes)?

Introduction:Transferases catalyze the transfer of functional groups between molecules. Recognizing typical group transfers helps classify enzymes quickly in biochemistry questions and exams.

Given Data / Assumptions:

• EC 2 class (transferases).
• Common transferred groups include one-carbon units and sugars.
• Representative examples: methyltransferases and glycosyltransferases.

Concept / Approach:Methyltransferases move CH3 groups from donors like S-adenosylmethionine to acceptors (DNA, proteins, metabolites). Glycosyltransferases move sugar moieties (e.g., UDP-glucose) onto acceptors to form glycosidic bonds. Both are canonical transferase reactions.

Step-by-Step Solution:Identify functional group types involved: methyl and glycosyl.Match to EC classification: both fall under transferases.Therefore, choose the option that includes both activities.

Verification / Alternative check:Enzyme Commission numbers: EC 2.1.x for one-carbon transfer (e.g., methyltransferases) and EC 2.4.x for glycosyltransferases, confirming both are transferases.

Why Other Options Are Wrong:Transfer of methyl groups: incomplete; does not include glycosyl.

Transfer of glycosyl groups: incomplete; does not include methyl.

None of these: incorrect because both are valid transferase activities.

Common Pitfalls:

• Confusing transferases with lyases or ligases.
• Assuming “transfer” refers only to phosphate (kinases are a subset, EC 2.7).

Final Answer:Both (a) and (b)