Succinyl-CoA synthetase (SCS) is a critical enzyme in the tricarboxylic acid (TCA) cycle that catalyzes the substrate-level phosphorylation step converting succinyl-CoA to succinate. A notable functional difference exists between the enzyme in plant and animal mitochondria concerning the type of nucleoside triphosphate produced during this reaction.

This article explains this difference and its metabolic significance.

Succinyl-CoA Synthetase and Nucleoside Triphosphate Production

• SCS catalyzes the reversible reaction:

  $$\text{Succinyl-CoA}+\text{NDP}+\text{Pi}\leftrightarrow \text{Succinate}+\text{CoA}+\text{NTP}$$

  where NDP is a nucleoside diphosphate (ADP or GDP) and NTP is the corresponding nucleoside triphosphate (ATP or GTP).

• The enzyme facilitates substrate-level phosphorylation, generating either ATP or GTP depending on the isoform and organism.

Differences Between Plants and Animals

• In plants:
  Succinyl-CoA synthetase primarily produces ATP during the conversion of succinyl-CoA to succinate in mitochondria. This ATP contributes directly to the cellular energy pool.

• In animals:
  Two isoforms of SCS exist: one specific for ATP and another specific for GTP. The GTP-producing isoform is prevalent in tissues involved in anabolic metabolism (e.g., liver, kidney), while the ATP-specific isoform is found in tissues with high oxidative metabolism (e.g., heart, skeletal muscle).

• This difference reflects tissue-specific metabolic demands and regulatory mechanisms.

Summary Table

Conclusion

The major functional difference between succinyl-CoA synthetase in plant and animal mitochondria is that it:

• Produces ATP in plants

• Produces GTP in animals

This distinction highlights metabolic specialization across species and tissues.

Correct answer: (3) Produces ATP in plants and GTP in animal

title: Major Functional Difference Between Succinyl-CoA Synthetase in Plant and Animal Mitochondria
slug: succinyl-coa-synthetase-plant-vs-animal-mitochondria
meta-description: Explore how succinyl-CoA synthetase differs between plants and animals, producing ATP in plants and GTP in animals, and understand the implications for energy metabolism.

Succinyl-CoA synthetase (SCS) is a critical enzyme in the tricarboxylic acid (TCA) cycle that catalyzes the substrate-level phosphorylation step converting succinyl-CoA to succinate. A notable functional difference exists between the enzyme in plant and animal mitochondria concerning the type of nucleoside triphosphate produced during this reaction.

This article explains this difference and its metabolic significance.

Succinyl-CoA Synthetase and Nucleoside Triphosphate Production

• SCS catalyzes the reversible reaction:

  $$\text{Succinyl-CoA}+\text{NDP}+\text{Pi}\leftrightarrow \text{Succinate}+\text{CoA}+\text{NTP}$$

  where NDP is a nucleoside diphosphate (ADP or GDP) and NTP is the corresponding nucleoside triphosphate (ATP or GTP).

• The enzyme facilitates substrate-level phosphorylation, generating either ATP or GTP depending on the isoform and organism.

Differences Between Plants and Animals

• In plants:
  Succinyl-CoA synthetase primarily produces ATP during the conversion of succinyl-CoA to succinate in mitochondria. This ATP contributes directly to the cellular energy pool.

• In animals:
  Two isoforms of SCS exist: one specific for ATP and another specific for GTP. The GTP-producing isoform is prevalent in tissues involved in anabolic metabolism (e.g., liver, kidney), while the ATP-specific isoform is found in tissues with high oxidative metabolism (e.g., heart, skeletal muscle).

• This difference reflects tissue-specific metabolic demands and regulatory mechanisms.

Summary Table

Conclusion

The major functional difference between succinyl-CoA synthetase in plant and animal mitochondria is that it:

• Produces ATP in plants

• Produces GTP in animals

This distinction highlights metabolic specialization across species and tissues.

Correct answer: (3) Produces ATP in plants and GTP in animal