| Autor: |
Ventura, Fátima V., Ijlst, Lodewijk, Ruiter, Jos, Ofman, Rob, Costa, Catarina G., Jakobs, Cornelis, Duran, Marinus, De Almeida, Isabel Tavares, Bieber, Loran L., Wanders, Ronald J. A. |
| Předmět: |
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| Zdroj: |
European Journal of Biochemistry; May98 Part 1, Vol. 253 Issue 3, p614-618, 5p, 2 Charts, 3 Graphs |
| Abstrakt: |
Using isolated rat liver mitochondria, in the absence or presence of malonyl-CoA (an inhibitor of carnitine palmitoyltransferase I), we have found that carnitine palmitoyltransferase II (CPT II) is active with palmitoyl-CoA as well as with its β-oxidation intermediates. A partially purified CPT II fraction from rat liver mitochondria was shown to be able to convert 3-hydroxypalmitoyl-CoA to 3-hydroxypalmitoylcarnitine, which could be identified by fast-atom-bombardment mass spectrometry. This apparent broad specificity of CPT II was further evaluated by kinetic studies using purified CPT II. It was found that CPT II readily accepts 3-oxopalmitoyl-CoA, palmitoyl-CoA, 3-hydroxypalmitoyl-CoA and 2,3-unsaturated palmitoyl-CoA as substrates with decreasing order of affinity. The apparent Vmax values found for the first three compounds were of the same order of magnitude; the 2,3-unsaturated acyl-CoA was the poorest substrate. Kinetic studies with purified CPT II showed 3-hydroxypalmitoyl-CoA to have the lowest K0.5 value (20 ± 6 μM) of all the CoA esters studied; the highest K0.5 value (65 ± 17 μM) was found for the 3-oxo intermediate. These findings support the hypothesis that CPT II is involved in the export of toxic long-chain acyl-CoA esters from the mitochondria by first converting them into the corresponding carnitine esters, followed by transport out of the mitochondria and subsequently out of the cell. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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