Biomedical subjects

M Fransen

Publications and source records attributed to M Fransen.

39 records · Page 3Linked to original sources

PubMed1994

Large-scale purification and further characterization of rat pristanoyl-CoA oxidase.

The elution of pristanoyl-CoA oxidase from butyl-Sepharose required unusually high concentrations of ethylene glycol, enabling the large-scale purification of this oxidase in a single chromatographic step. The enzyme, the native molecular mass of which was estimated previously at 415 kDa by gel filtration (Van Veldhoven, P.P., Vanhove, G., Vanhoutte, F., Dacremont, G., Eyssen, H. J. & Mannaerts, G. P. (1991) J. Biol. Chem. 266, 24676-24683), migrated as a 513-kDa protein during native gel electrophoresis. It showed a typical flavoprotein spectrum and probably binds 4 mol FAD/mol enzyme. Its amino acid composition was different from those of other known acyl-CoA oxidases. Screening of different rat tissues, either for enzyme activity or by immunoblotting, revealed the highest level of pristanoyl-CoA oxidase in liver, followed by kidney, intestinal mucosa, spleen and lung. The oxidase activities, measured with 2-methylpalmitoyl-CoA as the substrate, in livers from other vertebrates including man were low compared to rat. This was also confirmed by immunoblotting which provided a clear signal only in rat liver, possibly indicating that pristanoyl-CoA oxidase might be a rat-specific oxidase.

Amino Acids↗

PubMed1993

The CoA esters of 2-methyl-branched chain fatty acids and of the bile acid intermediates di- and trihydroxycoprostanic acids are oxidized by one single peroxisomal branched chain acyl-CoA oxidase in human liver and kidney.

Rat liver peroxisomes contain three acyl-CoA oxidases: palmitoyl-CoA oxidase, which oxidizes the CoA esters of straight chain fatty acids and prostaglandins; pristanoyl-CoA oxidase, which oxidizes the CoA esters of 2-methyl-branched fatty acids (e.g. pristanic acid); and trihydroxycoprostanoyl-CoA oxidase, which oxidizes the CoA esters of the bile acid intermediates di- and trihydroxycoprostanic acids (Van Veldhoven, P. P., Vanhove, G., Asselberghs, S., Eyssen, H. J., and Mannaerts, G. P. (1992) J. Biol. Chem. 267, 20065-20074). In the present report we demonstrate that human liver peroxisomes contain only two acyl-CoA oxidases: palmitoyl-CoA oxidase, which oxidizes the CoA esters of straight chain fatty acids and prostaglandins, and a novel branched chain acyl-CoA oxidase, which oxidizes the CoA esters of 2-methyl-branched fatty acids as well as those of the bile acid intermediates (which also possess a 2-methyl substitution in their side chains). The branched chain acyl-CoA oxidase was purified to near homogeneity by means of column chromatography. It appeared to be a 70-kDa monomeric protein that did not cross-react with antisera raised against rat palmitoyl-CoA oxidase and pristanoyl-CoA oxidase. No indication was found for the presence of a separate trihydroxycoprostanoyl-CoA oxidase in human liver. The branched chain acyl-CoA oxidase was present also in human kidney, suggesting that it is expressed in other extrahepatic tissues as well. Our results explain a number of clinical-chemical observations made in certain cases of peroxisomal beta-oxidation disorders.

Acyl Coenzyme A↗

PubMed1992

Presence of small GTP-binding proteins in the peroxisomal membrane.

Highly purified peroxisomal membranes stripped from their peripheral membrane proteins and only minimally contaminated with other membranes, contained three GTP-binding proteins of 29, 27 and 25 kDa, respectively. Bound radioactive GTP was displaced by unlabelled GTP, GTP analogs and GDP but not by GMP or other nucleotides. GTP binding was markedly decreased by trypsin treatment of intact purified peroxisomes; it increased 2-3-fold after pretreatment of the animals with a peroxisome proliferator. We conclude that the peroxisomal membrane contains small GTP-binding proteins that are exposed to the cytosol and that are firmly anchored in the membrane. We speculate that these proteins are involved in peroxisome multiplication by fission or budding during peroxisome biogenesis and proliferation.

Animals↗