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Dehydrogenases of the pentose phosphate pathway in rat liver peroxisomes.
Eur J Biochem. 1989 Jul 15; 183(1):75-82.EJ

Abstract

Subcellular distribution of pentose-phosphate cycle enzymes in rat liver was investigated, using differential and isopycnic centrifugation. The activities of the NADP+-dependent dehydrogenases of the pentose-phosphate pathway (glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase) were detected in the purified peroxisomal fraction as well as in the cytosol. Both dehydrogenases were localized in the peroxisomal matrix. Chronic administration of the hypolipidemic drug clofibrate (ethyl-alpha-p-chlorophenoxyisobutyrate) caused a 1.5-2.5-fold increase in the amount of glucose-6-phosphate and phosphogluconate dehydrogenases in the purified peroxisomes. Clofibrate decreased the phosphogluconate dehydrogenase, but did not alter glucose-6-phosphate dehydrogenase activity in the cytosolic fraction. The results obtained indicate that the enzymes of the non-oxidative segment of the pentose cycle (transketolase, transaldolase, triosephosphate isomerase and glucose-phosphate isomerase) are present only in a soluble form in the cytosol, but not in the peroxisomes or other particles, and that ionogenic interaction of the enzymes with the mitochondrial and other membranes takes place during homogenization of the tissue in 0.25 M sucrose. Similar to catalase, glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase are present in the intact peroxisomes in a latent form. The enzymes have Km values for their substrates in the millimolar range (0.2 mM for glucose-6-phosphate and 0.10-0.12 mM for 6-phosphogluconate). NADP+, but not NAD+, serves as a coenzyme for both enzymes. Glucose-6-phosphate dehydrogenase was inhibited by palmitoyl-CoA, and to a lesser extent by NADPH. Peroxisomal glucose-6-phosphate and phosphogluconate dehydrogenases have molecular mass of 280 kDa and 96 kDa, respectively. The putative functional role of pentose-phosphate cycle dehydrogenases in rat liver peroxisomes is discussed.

Authors+Show Affiliations

All-Union Research Center for Medico-Biological Problems of Narcology, Moscow, USSR.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

2753047

Citation

Antonenkov, V D.. "Dehydrogenases of the Pentose Phosphate Pathway in Rat Liver Peroxisomes." European Journal of Biochemistry, vol. 183, no. 1, 1989, pp. 75-82.
Antonenkov VD. Dehydrogenases of the pentose phosphate pathway in rat liver peroxisomes. Eur J Biochem. 1989;183(1):75-82.
Antonenkov, V. D. (1989). Dehydrogenases of the pentose phosphate pathway in rat liver peroxisomes. European Journal of Biochemistry, 183(1), 75-82.
Antonenkov VD. Dehydrogenases of the Pentose Phosphate Pathway in Rat Liver Peroxisomes. Eur J Biochem. 1989 Jul 15;183(1):75-82. PubMed PMID: 2753047.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Dehydrogenases of the pentose phosphate pathway in rat liver peroxisomes. A1 - Antonenkov,V D, PY - 1989/7/15/pubmed PY - 1989/7/15/medline PY - 1989/7/15/entrez SP - 75 EP - 82 JF - European journal of biochemistry JO - Eur. J. Biochem. VL - 183 IS - 1 N2 - Subcellular distribution of pentose-phosphate cycle enzymes in rat liver was investigated, using differential and isopycnic centrifugation. The activities of the NADP+-dependent dehydrogenases of the pentose-phosphate pathway (glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase) were detected in the purified peroxisomal fraction as well as in the cytosol. Both dehydrogenases were localized in the peroxisomal matrix. Chronic administration of the hypolipidemic drug clofibrate (ethyl-alpha-p-chlorophenoxyisobutyrate) caused a 1.5-2.5-fold increase in the amount of glucose-6-phosphate and phosphogluconate dehydrogenases in the purified peroxisomes. Clofibrate decreased the phosphogluconate dehydrogenase, but did not alter glucose-6-phosphate dehydrogenase activity in the cytosolic fraction. The results obtained indicate that the enzymes of the non-oxidative segment of the pentose cycle (transketolase, transaldolase, triosephosphate isomerase and glucose-phosphate isomerase) are present only in a soluble form in the cytosol, but not in the peroxisomes or other particles, and that ionogenic interaction of the enzymes with the mitochondrial and other membranes takes place during homogenization of the tissue in 0.25 M sucrose. Similar to catalase, glucose-6-phosphate dehydrogenase and phosphogluconate dehydrogenase are present in the intact peroxisomes in a latent form. The enzymes have Km values for their substrates in the millimolar range (0.2 mM for glucose-6-phosphate and 0.10-0.12 mM for 6-phosphogluconate). NADP+, but not NAD+, serves as a coenzyme for both enzymes. Glucose-6-phosphate dehydrogenase was inhibited by palmitoyl-CoA, and to a lesser extent by NADPH. Peroxisomal glucose-6-phosphate and phosphogluconate dehydrogenases have molecular mass of 280 kDa and 96 kDa, respectively. The putative functional role of pentose-phosphate cycle dehydrogenases in rat liver peroxisomes is discussed. SN - 0014-2956 UR - https://www.unboundmedicine.com/medline/citation/2753047/Dehydrogenases_of_the_pentose_phosphate_pathway_in_rat_liver_peroxisomes_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0014-2956&date=1989&volume=183&issue=1&spage=75 DB - PRIME DP - Unbound Medicine ER -