Succinate dehydrogenase

Jump to: navigation, search
File:Succinate Dehydrogenase 1YQ3 and Membrane.png
The structure of the Succinate-coenzyme Q reductase complex in a phospholipid membrane. The intermembrane space lies to the top of the image. SDHA, SDHB, SDHC and SDHD. Adapted from PDB: 1YQ3​.

WikiDoc Resources for Succinate dehydrogenase

Articles

Most recent articles on Succinate dehydrogenase

Most cited articles on Succinate dehydrogenase

Review articles on Succinate dehydrogenase

Articles on Succinate dehydrogenase in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Succinate dehydrogenase

Images of Succinate dehydrogenase

Photos of Succinate dehydrogenase

Podcasts & MP3s on Succinate dehydrogenase

Videos on Succinate dehydrogenase

Evidence Based Medicine

Cochrane Collaboration on Succinate dehydrogenase

Bandolier on Succinate dehydrogenase

TRIP on Succinate dehydrogenase

Clinical Trials

Ongoing Trials on Succinate dehydrogenase at Clinical Trials.gov

Trial results on Succinate dehydrogenase

Clinical Trials on Succinate dehydrogenase at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Succinate dehydrogenase

NICE Guidance on Succinate dehydrogenase

NHS PRODIGY Guidance

FDA on Succinate dehydrogenase

CDC on Succinate dehydrogenase

Books

Books on Succinate dehydrogenase

News

Succinate dehydrogenase in the news

Be alerted to news on Succinate dehydrogenase

News trends on Succinate dehydrogenase

Commentary

Blogs on Succinate dehydrogenase

Definitions

Definitions of Succinate dehydrogenase

Patient Resources / Community

Patient resources on Succinate dehydrogenase

Discussion groups on Succinate dehydrogenase

Patient Handouts on Succinate dehydrogenase

Directions to Hospitals Treating Succinate dehydrogenase

Risk calculators and risk factors for Succinate dehydrogenase

Healthcare Provider Resources

Symptoms of Succinate dehydrogenase

Causes & Risk Factors for Succinate dehydrogenase

Diagnostic studies for Succinate dehydrogenase

Treatment of Succinate dehydrogenase

Continuing Medical Education (CME)

CME Programs on Succinate dehydrogenase

International

Succinate dehydrogenase en Espanol

Succinate dehydrogenase en Francais

Business

Succinate dehydrogenase in the Marketplace

Patents on Succinate dehydrogenase

Experimental / Informatics

List of terms related to Succinate dehydrogenase


Overview

Succinate-coenzyme Q reductase (EC 1.3.5.1 ; succinate dehydrogenase) is an enzyme complex bound to the inner mitochondrial membrane. It is the only enzyme that participates in both the citric acid cycle and the mitochondrial electron transport chain (in this role it is often called Complex II). It is the only citric acid cycle enzyme that is membrane-bound. It is found in many aerobic and anaerobic organisms including Escherichia coli. The enzyme complex is a heterotetramer divided into three domains: SDHA, the catalytic domain; SDHB, the electron transfer subunit; SDHC/SDHD, the dimeric membrane anchor that contains β -type heme.

Function of the Succinate-coenzyme Q Reductase Complex

File:SuccDeh.svg
Function of the SDH Complex. Electron path shown by red arrows.
File:Succinate Dehydrogenase 1YQ3 Electron Carriers Labeled.png
Electron carriers of the SDH complex, from top right to bottom left; FADH2, 3x iron-sulphur centres, Haem and ubiquinnone.

The function of the enzyme is illustrated by following the transfer of electrons from succinate to ubiquinol. The electron path is shown in the diagram by the red arrows.

  1. Succinate is oxidized to fumarate by the SDHA subunit. SDHA contains a flavin adenine dinucleotide (FAD) cofactor that is covalently linked to a conserved histidine residue. This causes the oxidized FAD to be reduced to FADH2 in a two electron process. This is part of the citric acid cycle.
  2. The electron transfer subunit (SDHB) contains several iron-sulfur centers which relay electrons from SDHA to the membrane domains: a [2Fe-2S] cluster, a [4Fe-4S] cluster and a [3Fe-4S] cluster.
  3. These tunnelling electrons are transferred to Coenzyme Q, first to a ubiquinone molecule bound to the SDHC/SDHD dimer, reducing it to ubiquinol (QH2). Quinone reduction is a two-electron process and requires the formation of a ubisemiquinone radical intermediate.
  4. The resulting ubiquinol molecule is released, free to diffuse through the inner mitochondrial membrane to interact with subsequent enzymes of the mitochondrial respiratory chain (electron transport chain). A heme cofactor is also found within the membrane domain but its function has yet to be discovered.

Role in Disease

The fundamental role of succinate-coenzyme Q reductase in the electron transfer chain of mitochondria makes it vital in most multicellular organisms, removal of this enzyme from the genome has also been shown to be lethal at the embryonic stage in mice.

SDHB, SDHC and SDHD exhibit classic tumor suppressor gene behavior. SDHA has never been reported to be a tumor suppressor. The resulting disease depends on which gene is mutated.

The precise mechanism for each of these disease pathways is still being determined. See the specific gene for more details. Other diseases linked to succinate dehydrogenase include hereditary paraganglioma, obsessive compulsive disorder, generation of aromatic flatulants, and dwarfism.


Additional images

External links

de:Succinat-Dehydrogenase it:Succinato deidrogenasi (ubichinone)



Linked-in.jpg