- Malonate is competitive inhibitor of TCA cycle and structurally similar to
(1) Succinate (2) Malate
(3) Oxaloacetate (4) α-keto glutarate
Malonate is a well-known competitive inhibitor of the tricarboxylic acid (TCA) cycle, specifically targeting the enzyme succinate dehydrogenase. Understanding which molecule malonate structurally resembles helps explain its inhibitory mechanism and its impact on cellular respiration.
This article explores malonate’s role as a competitive inhibitor and identifies the TCA cycle intermediate it mimics.
Malonate and Its Role in the TCA Cycle
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Malonate is a dicarboxylic acid structurally similar to succinate, a four-carbon dicarboxylic acid intermediate in the TCA cycle.
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It competes with succinate for binding to the active site of succinate dehydrogenase (Complex II of the electron transport chain).
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By binding to the enzyme, malonate prevents succinate oxidation to fumarate, effectively blocking the TCA cycle and electron transport chain activity.
Structural Similarity to Succinate
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Succinate has two carboxyl groups attached to a four-carbon backbone.
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Malonate mimics this structure closely, allowing it to fit into the succinate binding site of succinate dehydrogenase.
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This structural mimicry underlies its competitive inhibition.
Impact of Malonate Inhibition
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Blocking succinate dehydrogenase halts the TCA cycle at the succinate step.
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This leads to decreased production of FADH₂ and NADH downstream.
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Consequently, ATP production via oxidative phosphorylation is reduced, impairing cellular energy metabolism.
Why Other Molecules Are Not Mimicked by Malonate
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Malate: Has an additional hydroxyl group and different structure; malonate does not mimic malate.
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Oxaloacetate: A four-carbon keto acid with a different structure; malonate does not resemble it closely.
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α-Ketoglutarate: A five-carbon keto acid; structurally distinct from malonate.
Summary Table
Option Structural Similarity to Malonate Role in TCA Cycle Correctness as Malonate Mimic Succinate High Substrate of succinate dehydrogenase Correct Malate Low TCA intermediate after fumarate Incorrect Oxaloacetate Low TCA intermediate before citrate Incorrect α-Ketoglutarate Low TCA intermediate before succinyl-CoA Incorrect Conclusion
Malonate is a competitive inhibitor of the TCA cycle enzyme succinate dehydrogenase due to its structural similarity to succinate. This mimicry allows malonate to bind the enzyme’s active site, blocking succinate oxidation and disrupting energy metabolism.
Correct answer: (1) Succinate
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23 Comments
Kirti Agarwal
September 18, 2025Succinate
Neha Yadav
September 20, 2025Malonate is similar to Succinate and target the succinate dehydrogenase
Bhawna Choudhary
September 21, 2025Malonate is one of the compititive inhibitors of kreb cycle
Malonate inhibit succinate dehydrogenase enzyme due to this conversion of succinate to fumarate is block
Sonal Nagar
September 22, 2025Succinate
Aafreen Khan
September 23, 2025Malonate is a structural analog of succinate and acts as a competitive inhibitor by binding to the active site of succinate dehydrogenase
HIMANI FAUJDAR
September 23, 2025Ans Malonate is a competitive inhibitor and structurally similar to succinate because it is a substrate of succinate dehydrogenase enzyme,
Which bind the enzyme’s active site, blocking succinate oxidation and disrupting energy metabolism.
Dharmpal Swami
September 23, 2025Melonate is a competitive inhibitor of krebs cycle
Bind with succinate dehydrogenase and block the formation of fumrate
Anurag Giri
September 23, 2025Succinate has two carboxyl groups attached to a four-carbon backbone.
Malonate mimics this structure closely, allowing it to fit into the succinate binding site of succinate dehydrogenase.
This structural mimicry underlies its competitive inhibition
Manisha choudhary
September 23, 2025Malonate dicarboxylic acid h and succinate bhi structure similar h
Malonate succinate s compete krta h and saccinate dehydrogenase enzyme (complex -2) s bind kr jata h succinate step p TCA cycle ko halts krta h
Pallavi Ghangas
September 23, 2025malonet is competitive inhibitor of succinate dehydrogenase
Aakansha sharma Sharma
September 23, 2025Malonate is similar to Succinate and target the succinate dehydrogenase
Heena Mahlawat
September 24, 2025Succinate
Roopal Sharma
September 24, 2025Malonate is structurally similar to succinate .
Nilofar Khan
September 24, 2025Malonate is competitive inhibitor of TCA cycle and structurally similar to succinate
Deepika sheoran
September 24, 2025Succinate
Minal Sethi
September 24, 2025Succinate
Soniya Shekhawat
September 25, 2025Malonate is competitive inhibitor of TCA cycle and structurally similar to succinate block succinate dehydrogenase and prevent formation of fumerate.
Mohd juber Ali
September 25, 2025Malonate(4c) structurlly similar to succinate (4c)and compete with succinate to bind active site of succinate dehydrogenase malonate prevents succinate oxidation to fumarate
Kavita Choudhary
September 26, 2025Matlate is competative inhibitior of TCA cycle and structuraly similar to succinate
Avni
September 26, 2025Correct answer: (1) Succinate
Varsha Tatla
September 27, 2025Malonate is structuraly similar to succinate that is compitative inhibitor for binding of succinate dehyrogenase
Arushi Saini
September 27, 2025Malonate is a competitive inhibitor of the TCA cycle enzyme succinate dehydrogenase due to its structural similarity to succinate. This mimicry allows malonate to bind the enzyme’s active site, blocking succinate oxidation and disrupting energy metabolism.
Payal Gaur
September 27, 2025Malonate is a compitative inhibitor of the TCA cycle and similar to succinate, bind with succinate dehydrogenase inhibit formation of fumarate