3-keto acid CoA transferase

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3-keto acid-CoA transferase 1
3-keto acid-CoA transferase 1
Bands / surface model of the SCOT dimer according to PDB  3DLX
Properties of human protein
Mass / length primary structure 481 amino acids
Secondary to quaternary structure Homodimer
Identifier
Gene name OXCT1
External IDs
Enzyme classification
EC, category 2.8.3.5 ,  transferase
Response type Transfer of CoA
Substrate Succinyl-CoA + 3-keto acid
Products Succinate + 3-keto acid CoA

3-keto acid-CoA transferases (Scot) are enzymes which transfer coenzyme A from succinyl-CoA to γ- keto acids (especially acetoacetate ). This is the rate-limiting reaction step in the breakdown of the keto body ; the other two reactions are reversals of the building reactions. Scot enzymes are found in higher eukaryotes and some bacteria . Two scots are known to exist in humans: 3-keto acid – CoA transferase 1 (Scot-S) and 3-keto acid – CoA transferase 2 (Scot-t) .

The presence of scot in the tissue indicates whether keto bodies can be broken down there and used as an energy supplier. Both scot can be found in the mitochondria matrix. Scot-S is not found in the liver but can be found abundantly in the heart , kidneys , brain and muscles . Scot-t is only localized in the testicles (" t estis"). Mutations in OXCT1 - gene can Scot S deficiency and this is a form of ketoacidosis cause. With physical training, the Scot activity in muscles can be increased many times over, especially in diabetics.

Scot-S is one of the proteins whose tryptophan residues by reactive oxygen species nitrided be. It has been shown in rats that protein nitrated in this way accumulates in heart muscles with age. The modified enzyme had a higher activity than the unchanged one.

Catalyzed equilibrium

Acetoacetate + succinyl-CoA ⇔ acetoacetyl-CoA + succinate

CoA is transferred to acetoacetate. Instead of acetoacetic acid, many other γ-keto acids can act as substrates, but the reaction is then slowed down. Instead of succinyl-CoA, malonyl-CoA is also accepted. The intermediate is an unstable acid anhydride that is formed with the protein.

Individual evidence

  1. ↑ Swiss Institute of Bioinformatics (SIB): PROSITE documentation PDOC00980. Retrieved September 20, 2011 .
  2. ↑ a b UniProt P55809
  3. ↑ El Midaoui A, Chiasson JL, Tancrède G, Nadeau A: Physical training reverses defect in 3-ketoacid CoA-transferase activity in skeletal muscle of diabetic rats . In: Am. J. Physiol. Endocrinol. Metab. . 288, No. 4, April 2005, pp. E748-52. doi : 10.1152 / ajpendo.00515.2004 . PMID 15774485 .
  4. ↑ Bregere C, Rebrin I, Sohal RS: Detection and characterization of in vivo nitration and oxidation of tryptophan residues in proteins . In: Meth. Enzymol. . 441, 2008, pp. 339-49. doi : 10.1016 / S0076-6879 (08) 01219-6 . PMID 18554544 .
  5. ↑ expasy entry

Web links

Wikibooks: Biochemie_und_Pathobiochemie: ketone body biosynthesis  - learning and teaching materials