succinate dehydrogenase (quinone) activity

Definition

Target type: molecularfunction

Catalysis of the reaction: a quinone + succinate = a quinol + fumarate. [RHEA:40523]

Succinate dehydrogenase (quinone) activity is a crucial step in the electron transport chain, a series of protein complexes embedded in the inner mitochondrial membrane that drives ATP production. This activity, catalyzed by the enzyme succinate dehydrogenase (SDH), is responsible for the oxidation of succinate to fumarate, a key reaction in the citric acid cycle. The electrons released during this oxidation are transferred to ubiquinone (Q), a small lipid-soluble molecule that acts as an electron carrier in the respiratory chain. The transfer of electrons from succinate to ubiquinone is coupled to the translocation of protons across the inner mitochondrial membrane, creating a proton gradient that is used to drive ATP synthesis by ATP synthase.

Specifically, SDH, also known as complex II of the electron transport chain, consists of four subunits: SDHA, SDHB, SDHC, and SDHD. SDHA and SDHB are located in the mitochondrial matrix and contain the active site for succinate oxidation. SDHC and SDHD are embedded in the inner mitochondrial membrane and bind ubiquinone. The enzyme utilizes a flavin adenine dinucleotide (FAD) prosthetic group to accept electrons from succinate and a series of iron-sulfur clusters to transfer these electrons to ubiquinone. The transfer of electrons to ubiquinone is energetically favorable, driving the translocation of protons across the membrane. The proton gradient created by this process contributes to the overall electrochemical potential difference across the mitochondrial membrane, which is essential for ATP production.

In summary, succinate dehydrogenase (quinone) activity plays a critical role in cellular respiration by catalyzing the oxidation of succinate, generating electrons that are used to reduce ubiquinone, and contributing to the proton gradient that drives ATP synthesis.'
"

Proteins (1)

Compounds (1)