3-oxoacid CoA-transferase

3- ketoacid CoA transferase ( Scot ) are called enzymes, the coenzyme A from succinyl- CoA to γ -keto acids (especially acetoacetate ) transmitted. This is the rate-limiting step in the degradation reaction of ketone bodies; the other two reactions are reversals of the assembly reactions. Scot - enzymes are found in higher eukaryotes and some bacteria. In humans two Scot are known: 3- ketoacid CoA transferase 1 ( Scot -S ) and 3- keto acid CoA -transferase 2 ( Scot -t).

The presence of Scot in the tissue indicates whether ketone bodies can be broken down and used as an energy there. Both Scot can be found in the mitochondrial matrix. Scot -S is not present in the liver, but can be abundant detected in heart, kidney, brain and muscles. Scot -t is localized only in the testis ( " testis "). Mutations in the gene can cause OXCT1 Scot S deficiency and this is a form of ketoacidosis. With the physical training Scot activity can be increased by a multiple in the muscles, in particular in diabetics.

Scot -S is one of the proteins, the tryptophan residues are nitrated by reactive oxygen species. In rats it has been demonstrated that such nitrated protein accumulates in aged heart muscle. The modified enzyme showed a higher activity than the unmodified.

Catalysed equilibrium

Acetoacetate succinyl -CoA ⇔ acetoacetyl-CoA succinate

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

Human Genome Organisation Succinyl-CoA Nitration Digital Object Identifier
13322
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