The class of enzymes that cleave covalent bond in a substrate through elimination reaction and yield a double bond or ring structure in the resulting product
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A classic example of a lyase is aldolase in glycolysis, which cleaves fructose 1,6-bisphosphate into dihydroxyacetone phosphate and glyceraldehyde 3-phosphate.
Another is fumarase (when running in reverse).
Step 1: Understanding the Concept:
Enzymes are systematically classified by the Enzyme Commission (EC) into six main functional classes based on the type of chemical reaction they catalyze. Detailed Explanation:
Let us review the definition of each enzyme class in the options:
- Lyases (EC 4) (A): These enzymes catalyze the cleavage of C-C, C-O, C-N, and other covalent bonds by elimination reactions, leaving double bonds or rings.
Alternatively, they can catalyze the reverse reaction (addition of groups to double bonds). They do not require water (hydrolysis) or oxidation/reduction to break these bonds.
- Oxidoreductases (EC 1) (B): These catalyze oxidation-reduction reactions, transferring electrons or hydrogen atoms.
- Transferases (EC 2) (C): These catalyze the transfer of functional groups (such as methyl or phosphate groups) from one molecule to another.
- Isomerases (EC 5) (D): These catalyze structural rearrangements within a single molecule (isomerization). Step 2: Final Answer:
Lyases are the class of enzymes that cleave bonds through elimination, yielding a double bond or ring structure. This corresponds to option (A).
