Sandbox 212: Difference between revisions
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The extraction of a hydrogen atom leads to the development of a tetrahedral oxyanion intermediate. This oxyanion is stabilized by the side chain hydroxyl of serine 554 through hydrogen bonding as well as by the positive charge on the trimethylammonium group of carnitine. Since the positive charge of the carnitine substrate is necessary for the carnitine acyltransferase mediated reaction to happen, this catalysis can be described as '''substrate-assisted catalysis'''.<ref>PMID:15591000</ref> | The extraction of a hydrogen atom leads to the development of a tetrahedral oxyanion intermediate. This oxyanion is stabilized by the side chain hydroxyl of serine 554 through hydrogen bonding as well as by the positive charge on the trimethylammonium group of carnitine. Since the positive charge of the carnitine substrate is necessary for the carnitine acyltransferase mediated reaction to happen, this catalysis can be described as '''substrate-assisted catalysis'''.<ref>PMID:15591000</ref> | ||
== Regulation == | == Regulation == | ||
One of the most common regulation system involves inhibition by malonyl-CoA, an intermediate in the synthesis of fatty acids. Malonyl-CoA inhibits long-chain carnitine acyltransferase activity by all three enzymes at similar concentrations in the physiological range. Moreover, the mitochondrial ( CAT) and peroxisomal (COT) enzymes can also be regulated through mRNA transcription by a number of shared factors. Although the microsomal enzyme is less well studied, there does, indeed, appear to be a pattern of coordinate regulation for this system. | |||
== Carnitine acetyltransferase deficiency and diseases == | == Carnitine acetyltransferase deficiency and diseases == | ||
Mutation and dysregulation of CPTs are linked to serious human diseases. Recessive mutations of CPT-I and CPT-IICPT-I and CPT-II are crucial for the beta-oxidation of long-chain fatty acids in the mitochondria by enabling their transport across the mitochondrial membrane. can produce hypoketonemia and hypoglycemia in patients, while CPT-II deficiency is the most common cause of abnormal lipid metabolism in skeletal muscle.Single-point mutations as well as insertions/deletions in the CPT genes can produce the clinical phenotype. The hypoglycemia observed in patients with reduced CPT-I activity suggests that antagonists of CPT-Is may be able to lower blood glucose levels. A covalent CPT-I inhibitor, etomoxir, can lower blood glucose levels in diabetic animals and humans, showing that such inhibitors may be efficacious for the treatment of type 2 diabetes. | Mutation and dysregulation of CPTs are linked to serious human diseases. Recessive mutations of CPT-I and CPT-IICPT-I and CPT-II are crucial for the beta-oxidation of long-chain fatty acids in the mitochondria by enabling their transport across the mitochondrial membrane. can produce hypoketonemia and hypoglycemia in patients, while CPT-II deficiency is the most common cause of abnormal lipid metabolism in skeletal muscle.Single-point mutations as well as insertions/deletions in the CPT genes can produce the clinical phenotype. The hypoglycemia observed in patients with reduced CPT-I activity suggests that antagonists of CPT-Is may be able to lower blood glucose levels. A covalent CPT-I inhibitor, etomoxir, can lower blood glucose levels in diabetic animals and humans, showing that such inhibitors may be efficacious for the treatment of type 2 diabetes. | ||
== References == | == References == | ||
<references/> | <references/> | ||