Succinyl-CoA: Difference between revisions

Latest revision as of 10:50, 15 February 2025

Overview[edit]

Succinyl-CoA is a key intermediate in the citric acid cycle (also known as the Krebs cycle or tricarboxylic acid cycle), which is a central metabolic pathway in aerobic respiration. It plays a crucial role in the conversion of energy stored in nutrients into adenosine triphosphate (ATP), the energy currency of the cell.

Structure[edit]

Succinyl-CoA is a thioester of succinic acid and coenzyme A. The structure of succinyl-CoA includes a four-carbon dicarboxylic acid (succinic acid) linked to coenzyme A via a thioester bond. This high-energy bond is crucial for its role in metabolic reactions.

Role in Metabolism[edit]

Succinyl-CoA is involved in several important metabolic pathways:

Citric Acid Cycle[edit]

In the citric acid cycle, succinyl-CoA is formed from _-ketoglutarate through the action of the enzyme _-ketoglutarate dehydrogenase complex. This reaction is a key step in the cycle, as it involves the decarboxylation of _-ketoglutarate and the reduction of NAD+ to NADH.

Succinyl-CoA is then converted to succinate by the enzyme succinyl-CoA synthetase, which is coupled with the phosphorylation of guanosine diphosphate (GDP) to guanosine triphosphate (GTP) or adenosine diphosphate (ADP) to ATP, depending on the organism. This is one of the few substrate-level phosphorylation reactions in the citric acid cycle.

Heme Biosynthesis[edit]

Succinyl-CoA is also a precursor in the biosynthesis of heme, an essential component of hemoglobin, myoglobin, and various cytochromes. In this pathway, succinyl-CoA condenses with glycine to form _-aminolevulinic acid, a key step catalyzed by the enzyme _-aminolevulinic acid synthase.

Ketone Body Metabolism[edit]

In the metabolism of ketone bodies, succinyl-CoA is involved in the conversion of acetoacetate to acetoacetyl-CoA, which is then further metabolized to acetyl-CoA. This process is important during periods of fasting or low carbohydrate intake, where ketone bodies serve as an alternative energy source.

Clinical Significance[edit]

Disruptions in the pathways involving succinyl-CoA can lead to metabolic disorders. For example, deficiencies in the enzymes of the citric acid cycle can result in energy production issues, while defects in heme biosynthesis can lead to conditions such as porphyria.

Related Pages[edit]

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-'''Succinyl-CoA''' is a significant intermediate in multiple metabolic pathways in [[biochemistry]]. It is a substrate in the [[citric acid cycle]], also known as the Krebs cycle or TCA cycle, and plays a crucial role in the [[synthesis]] of [[heme]] in mammals.
+{{DISPLAYTITLE:Succinyl-CoA}}
+== Overview ==
+[[File:Succinyl-CoA.svg|thumb|right|Structure of Succinyl-CoA]]
+'''Succinyl-CoA''' is a key intermediate in the [[citric acid cycle]] (also known as the [[Krebs cycle]] or [[tricarboxylic acid cycle]]), which is a central metabolic pathway in [[aerobic respiration]]. It plays a crucial role in the conversion of energy stored in nutrients into [[adenosine triphosphate]] (ATP), the energy currency of the cell.
 == Structure ==
+Succinyl-CoA is a [[thioester]] of [[succinic acid]] and [[coenzyme A]]. The structure of succinyl-CoA includes a four-carbon dicarboxylic acid (succinic acid) linked to coenzyme A via a thioester bond. This high-energy bond is crucial for its role in metabolic reactions.
+== Role in Metabolism ==
+Succinyl-CoA is involved in several important metabolic pathways:
-Succinyl-CoA is a molecule composed of a [[succinate]] moiety, a [[coenzyme A]] moiety, and a high-energy bond connecting them. The succinate moiety is a four-carbon dicarboxylic acid, while coenzyme A is a complex molecule that carries acyl groups in the body.
+=== Citric Acid Cycle ===
+In the citric acid cycle, succinyl-CoA is formed from [[_-ketoglutarate]] through the action of the enzyme [[_-ketoglutarate dehydrogenase complex]]. This reaction is a key step in the cycle, as it involves the decarboxylation of _-ketoglutarate and the reduction of [[NAD+]] to [[NADH]].
-== Role in Metabolism ==
+Succinyl-CoA is then converted to [[succinate]] by the enzyme [[succinyl-CoA synthetase]], which is coupled with the phosphorylation of [[guanosine diphosphate]] (GDP) to [[guanosine triphosphate]] (GTP) or [[adenosine diphosphate]] (ADP) to ATP, depending on the organism. This is one of the few substrate-level phosphorylation reactions in the citric acid cycle.
-Succinyl-CoA plays a pivotal role in the citric acid cycle. It is the only intermediate that participates in a substrate-level phosphorylation, in which a phosphate group is transferred from the substrate molecule to [[adenosine diphosphate]] (ADP) to form [[adenosine triphosphate]] (ATP). This reaction is catalyzed by the enzyme [[succinyl-CoA synthetase]].
+=== Heme Biosynthesis ===
+Succinyl-CoA is also a precursor in the biosynthesis of [[heme]], an essential component of [[hemoglobin]], [[myoglobin]], and various [[cytochromes]]. In this pathway, succinyl-CoA condenses with [[glycine]] to form [[_-aminolevulinic acid]], a key step catalyzed by the enzyme [[_-aminolevulinic acid synthase]].
-In addition to its role in the citric acid cycle, succinyl-CoA is also involved in the synthesis of heme, a component of [[hemoglobin]], the oxygen-carrying molecule in red blood cells. The process, known as the [[heme synthesis pathway]], begins in the mitochondria with the condensation of succinyl-CoA and [[glycine]] to form [[delta-aminolevulinic acid]] (ALA).
+=== Ketone Body Metabolism ===
+In the metabolism of [[ketone bodies]], succinyl-CoA is involved in the conversion of [[acetoacetate]] to [[acetoacetyl-CoA]], which is then further metabolized to [[acetyl-CoA]]. This process is important during periods of fasting or low carbohydrate intake, where ketone bodies serve as an alternative energy source.
 == Clinical Significance ==
+Disruptions in the pathways involving succinyl-CoA can lead to metabolic disorders. For example, deficiencies in the enzymes of the citric acid cycle can result in energy production issues, while defects in heme biosynthesis can lead to conditions such as [[porphyria]].
-Abnormalities in the metabolism of succinyl-CoA can lead to various clinical conditions. For instance, a deficiency in the enzyme succinyl-CoA synthetase can result in a buildup of succinyl-CoA, leading to a condition known as [[succinyl-CoA ligase deficiency]], which can cause a range of symptoms from mild to severe, including developmental delay, muscle weakness, and failure to thrive.
+== Related Pages ==
+* [[Citric acid cycle]]
+* [[Coenzyme A]]
+* [[Heme]]
+* [[Metabolism]]
+* [[Thioester]]
 [[Category:Biochemistry]]
 [[Category:Metabolism]]
-{{biochemistry-stub}}
-{{medicine-stub}}