Publications

• Carnitine palmitoyltransferase 2: New insights on the substrate specificity and implications for acylcarnitine profiling.

  Violante S., Ijlst L., van Lenthe H., de Almeida I.T., Wanders R.J., Ventura F.V.

  Over the last years acylcarnitines have emerged as important biomarkers for the diagnosis of mitochondrial fatty acid beta-oxidation (mFAO) and branched-chain amino acid oxidation disorders assuming they reflect the potentially toxic acyl-CoA species, accumulating intramitochondrially upstream of ... >> More

  Over the last years acylcarnitines have emerged as important biomarkers for the diagnosis of mitochondrial fatty acid beta-oxidation (mFAO) and branched-chain amino acid oxidation disorders assuming they reflect the potentially toxic acyl-CoA species, accumulating intramitochondrially upstream of the enzyme block. However, the origin of these intermediates still remains poorly understood. A possibility exists that carnitine palmitoyltransferase 2 (CPT2), member of the carnitine shuttle, is involved in the intramitochondrial synthesis of acylcarnitines from accumulated acyl-CoA metabolites. To address this issue, the substrate specificity profile of CPT2 was herein investigated. Saccharomyces cerevisiae homogenates expressing human CPT2 were incubated with saturated and unsaturated C2-C26 acyl-CoAs and branched-chain amino acid oxidation intermediates. The produced acylcarnitines were quantified by ESI-MS/MS. We show that CPT2 is active with medium (C8-C12) and long-chain (C14-C18) acyl-CoA esters, whereas virtually no activity was found with short- and very long-chain acyl-CoAs or with branched-chain amino acid oxidation intermediates. Trans-2-enoyl-CoA intermediates were also found to be poor substrates for CPT2. Inhibition studies performed revealed that trans-2-C16:1-CoA may act as a competitive inhibitor of CPT2 (K(i) of 18.8 microM). The results obtained clearly demonstrate that CPT2 is able to reverse its physiological mechanism for medium and long-chain acyl-CoAs contributing to the abnormal acylcarnitines profiles characteristic of most mFAO disorders. The finding that trans-2-enoyl-CoAs are poorly handled by CPT2 may explain the absence of trans-2-enoyl-carnitines in the profiles of mitochondrial trifunctional protein deficient patients, the only defect where they accumulate, and the discrepancy between the clinical features of this and other long-chain mFAO disorders such as very long-chain acyl-CoA dehydrogenase deficiency. << Less

  Biochim. Biophys. Acta 1802:728-732(2010) [PubMed] [EuropePMC]

  This publication is cited by 10 other entries.

• Rat liver metabolism of dicarboxylic acids.

  Vamecq J., Draye J.P., Brison J.

  Recently, we demonstrated in rat liver that dicarboxylic acids containing more than five carbons can be activated by a microsomal dicarboxylyl-CoA synthetase (J. Vamecq, E. de Hoffmann, and F. Van Hoof. Biochem. J. 230: 683-693, 1985). The products of this reaction, dicarboxylyl-CoA esters, were f ... >> More

  Recently, we demonstrated in rat liver that dicarboxylic acids containing more than five carbons can be activated by a microsomal dicarboxylyl-CoA synthetase (J. Vamecq, E. de Hoffmann, and F. Van Hoof. Biochem. J. 230: 683-693, 1985). The products of this reaction, dicarboxylyl-CoA esters, were found to be substrates for an H2O2-generating dicarboxylyl-CoA oxidase. In the present work we report that 1) the catalytic center or the essential domains of dicarboxylyl-CoA synthetase are located at the cytosolic aspect of the endoplasmic reticulum membrane; 2) dicarboxylyl-CoA oxidase is optimally active on dodecanedioyl-CoA and is a peroxisomal enzyme; 3) cyanide-insensitive dodecanedioyl-CoA oxidation (NADH production) is catalyzed by rat liver homogenates. Cell fractionation studies disclose that, similar to dodecanedioyl-CoA oxidase (H2O2 production), the cyanide-insensitive dodecanedioyl-CoA oxidizing activity also belongs to peroxisomes; 4) a dodecanedioyl-CoA oxidoreductase reaction can be assayed by the dichlorphenolindophenol procedure in rat liver homogenates, and the activity is abundant in peroxisomal, mitochondrial, and soluble fractions; 5) by contrast with monocarboxylyl-CoA esters, the dicarboxylyl-CoAs are apparently not substrates for mitochondrial fatty acid oxidation; however, the use of dicarboxylylcarnitine esters as direct substrate for mitochondria suggests the existence of an active beta-oxidation of dicarboxylates in these organelles, which is further confirmed by experiments in which mitochondria are permeabilized with digitonin; 6) the in vivo oxidation of infused dodecanedioic acid results in a rapid appearance in urine of medium-chain dicarboxylic acids, with only 30-50% of the infused dose recovered in urine. << Less

  Am J Physiol 256:G680-8(1989) [PubMed] [EuropePMC]

  This publication is cited by 6 other entries.