OGDH

OGDH or Oxoglutarate dehydrogenase is a key enzyme involved in the Krebs cycle, also known as the citric acid cycle or TCA cycle. This enzyme catalyzes the conversion of alpha-ketoglutarate into succinyl-CoA and carbon dioxide, a critical step in the cycle that is responsible for the majority of cellular energy production.

Structure

OGDH is a large, multi-subunit enzyme complex located in the mitochondria. It is composed of multiple copies of three different subunits: E1, E2, and E3. The E1 subunit is a thiamine pyrophosphate-dependent enzyme, the E2 subunit is a dihydrolipoamide succinyltransferase, and the E3 subunit is a dihydrolipoamide dehydrogenase.

Function

The primary function of OGDH is to catalyze the decarboxylation of alpha-ketoglutarate, a process that involves the removal of a carboxyl group. This reaction produces succinyl-CoA, a compound that is then used in the next step of the Krebs cycle. The reaction also produces NADH, a molecule that is used in the electron transport chain to produce ATP, the main energy currency of the cell.

Clinical significance

Mutations in the genes encoding the subunits of OGDH can lead to a variety of metabolic disorders, including alpha-ketoglutarate dehydrogenase deficiency. This rare disorder is characterized by a buildup of alpha-ketoglutarate and a decrease in the levels of succinyl-CoA and NADH. Symptoms can include developmental delay, seizures, and lactic acidosis.

File:Alpha-ketoglutarate.svg

Alpha-ketoglutarate, the substrate of OGDH

See also

• Krebs cycle
• Enzyme
• Mitochondria
• Metabolic disorders