Methylmalonyl-CoA Mutase

Definition

Methylmalonyl-CoA mutase is an enzyme that catalyzes a key step in the catabolism of certain amino acids and odd-chain fatty acids. It is an essential enzyme involved in the breakdown and utilization of these molecules for energy production within the body.

5 Must Know Facts For Your Next Test

1. Methylmalonyl-CoA mutase catalyzes the conversion of methylmalonyl-CoA to succinyl-CoA, a key step in the catabolism of certain amino acids and odd-chain fatty acids.
2. The enzyme requires the cofactor cobalamin (vitamin B12) for its activity, and vitamin B12 deficiency can lead to the accumulation of methylmalonyl-CoA and impaired energy metabolism.
3. Impaired methylmalonyl-CoA mutase activity can result in the metabolic disorder methylmalonic acidemia, characterized by the accumulation of methylmalonic acid and other toxic metabolites.
4. The succinyl-CoA produced by the methylmalonyl-CoA mutase reaction can then enter the tricarboxylic acid (TCA) cycle, where it can be further metabolized to generate ATP and other essential molecules.
5. Methylmalonyl-CoA mutase is a key enzyme in the catabolism of triacylglycerols, as it is involved in the breakdown of odd-chain fatty acids released during β-oxidation.

Review Questions

• Explain the role of methylmalonyl-CoA mutase in the catabolism of triacylglycerols.
  • Methylmalonyl-CoA mutase plays a crucial role in the catabolism of triacylglycerols by catalyzing the conversion of methylmalonyl-CoA to succinyl-CoA, a key intermediate that can then enter the tricarboxylic acid (TCA) cycle. This enzyme is involved in the breakdown of odd-chain fatty acids released during the β-oxidation of triacylglycerols, allowing for the further metabolism of these molecules to generate energy in the form of ATP.
• Describe the relationship between methylmalonyl-CoA mutase and vitamin B12 (cobalamin) in the context of energy metabolism.
  • Methylmalonyl-CoA mutase requires the cofactor cobalamin (vitamin B12) for its proper functioning. Vitamin B12 deficiency can lead to the accumulation of methylmalonyl-CoA, which can impair energy metabolism and contribute to the development of metabolic disorders like methylmalonic acidemia. The dependence of methylmalonyl-CoA mutase on vitamin B12 highlights the importance of adequate nutrient intake for the efficient catabolism of certain amino acids and odd-chain fatty acids, which are essential for energy production within the body.
• Analyze the significance of the methylmalonyl-CoA mutase reaction in the overall context of triacylglycerol catabolism and energy homeostasis.
  • The methylmalonyl-CoA mutase reaction is a crucial step in the catabolism of triacylglycerols, as it facilitates the conversion of methylmalonyl-CoA, an intermediate in the breakdown of odd-chain fatty acids, into succinyl-CoA. Succinyl-CoA can then enter the tricarboxylic acid (TCA) cycle, where it can be further metabolized to generate ATP and other essential molecules. The efficient functioning of methylmalonyl-CoA mutase, supported by adequate vitamin B12 levels, is therefore vital for maintaining energy homeostasis and overall metabolic health. Impairment of this enzyme can lead to the accumulation of toxic metabolites and disruption of energy production pathways, highlighting the significance of this reaction in the broader context of triacylglycerol catabolism and energy metabolism.

Related terms

Cobalamin (Vitamin B12): A cofactor required for the proper functioning of methylmalonyl-CoA mutase. Vitamin B12 deficiency can lead to the accumulation of methylmalonyl-CoA and impaired energy metabolism.

Propionyl-CoA:

A metabolic intermediate that is converted to methylmalonyl-CoA by the action of methylmalonyl-CoA carboxylase, an enzyme upstream of methylmalonyl-CoA mutase in the catabolic pathway.

Succinyl-CoA:

The product of the methylmalonyl-CoA mutase reaction, which can then enter the tricarboxylic acid (TCA) cycle for further energy production.