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Verfasst von:Baumgart-Vogt, Eveline [VerfasserIn]   i
 Fahimi, H. Dariush [VerfasserIn]   i
 Stich, Andrea [VerfasserIn]   i
 Völkl, Alfred [VerfasserIn]   i
Titel:L-lactate dehydrogenase A4- and A3B isoforms are bona fide peroxisomal enzymes in rat liver
Verf.angabe:Eveline Baumgart, H. Dariush Fahimi, Andrea Stich, Alfred Völkl
Jahr:1996
Umfang:10 S.
Fussnoten:Online verfügbar: 6. Februay 1996, Artikelversion: 4. Januar 2021 ; Im Titel sind "3" und "4" tiefgestellt ; Gesehen am 20.01.2025
Titel Quelle:Enthalten in: The journal of biological chemistry
Ort Quelle:Bethesda, Md. : ASBMB Publications, 1905
Jahr Quelle:1996
Band/Heft Quelle:271(1996), 7, Seite 3846-3855
ISSN Quelle:1083-351X
Abstract:The subcellular localization of L-lactate dehydrogenase (LDH) in rat hepatocytes has been studied by analytical subcellular fractionation combined with the immunodetection of LDH in isolated subcellular fractions and liver sections by immunoblotting and immunoelectron microscopy. The results clearly demonstrate the presence of LDH in the matrix of peroxisomes in addition to the cytosol. Both cytosolic and peroxisomal LDH subunits have the same molecular mass (35.0 kDa) and show comparable cross-reactivity with an anti-cytosolic LDH antibody. As revealed by activity staining or immunoblotting after isoelectric focussing, both intracellular compartments contain the same liver-specific LDH-isoforms (LDH-A4 > LDH-A3B) with the peroxisomes comprising relatively more LDH-A3B than the cytosol. Selective KCl extraction as well as resistance to proteinase K and immunoelectron microscopy revealed that at least 80% of the LDH activity measured in highly purified peroxisomal fractions is due to LDH as a bona fide peroxisomal matrix enzyme. In combination with the data of cell fractionation, this implies that at least 0.5% of the total LDH activity in hepatocytes is present in peroxisomes. Since no other enzymes of the glycolytic pathway (such as phosphoglucomutase, phosphoglucoisomerase, and glyceraldehyde-3-phosphate dehydrogenase) were found in highly purified peroxisomal fractions, it does not seem that LDH in peroxisomes participates in glycolysis. Instead, the marked elevation of LDH in peroxisomes of rats treated with the hypolipidemic drug bezafibrate, concomitantly to the induction of the peroxisomal β-oxidation enzymes, strongly suggests that intraperoxisomal LDH may be involved in the reoxidation of NADH generated by the β-oxidation pathway. The interaction of LDH and the peroxisomal palmitoyl-CoA β-oxidation system could be verified in a modified β-oxidation assay by adding increasing amounts of pyruvate to the standard assay mixture and recording the change of NADH production rates. A dose-dependent decrease of NADH produced was simulated with the lowest NADH value found at maximal LDH activity. The addition of oxamic acid, a specific inhibitor of LDH, to the system or inhibition of LDH by high pyruvate levels (up to 20 mM) restored the NADH values to control levels. A direct effect of pyruvate on palmitoyl-CoA oxidase and enoyl-CoA hydratase was excluded by measuring those enzymes individually in separate assays. An LDH-based shuttle across the peroxisomal membrane should provide an efficient system to regulate intraperoxisomal NAD+/NADH levels and maintain the flux of fatty acids through the peroxisomal β-oxidation spiral.
DOI:doi:10.1074/jbc.271.7.3846
URL:Bitte beachten Sie: Dies ist ein Bibliographieeintrag. Ein Volltextzugriff für Mitglieder der Universität besteht hier nur, falls für die entsprechende Zeitschrift/den entsprechenden Sammelband ein Abonnement besteht oder es sich um einen OpenAccess-Titel handelt.

Volltext: https://doi.org/10.1074/jbc.271.7.3846
 Volltext: https://www.sciencedirect.com/science/article/pii/S0021925817459369
 DOI: https://doi.org/10.1074/jbc.271.7.3846
Datenträger:Online-Ressource
Sprache:eng
K10plus-PPN:1915141591
Verknüpfungen:→ Zeitschrift

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