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S Beeckmans

Publications and source records attributed to S Beeckmans.

30 records · Page 2Linked to original sources
PubMed1983

Chicken heart citrate synthase: some mechanism studies.

Some mechanism studies on chicken and pig citrate synthase are described. Gibacron Blue F3GA apparently binds into both the oxaloacetate and the acetyl-CoA subsites of the enzyme. Protection by ligands against urea-induced denaturation indicates that several di(tri)-carboxylic acids bind into the oxaloacetate subsite, whereas ATP, but not Mg2+ ATP, binds into the acetyl-CoA subsite. Oxaloacetate, citrate and D-malate induce a transconformation in the enzyme, whereas alpha-ketoglutarate, L-malate and succinate do not.

Animals↗
PubMed1981

Demonstration of physical interactions between consecutive enzymes of the citric acid cycle and of the aspartate-malate shuttle. A study involving fumarase, malate dehydrogenase, citrate synthesis and aspartate aminotransferase.

By means of covalently immobilized fumarase and mitochondrial or cytoplasmic malate dehydrogenase we were able to detect physical interactions between different enzymes of the citric acid cycle (fumarase with malate dehydrogenase, malate dehydrogenase with citrate synthase and fumarase with citrate synthase) and between the enzymes of both mitochondrial and cytoplasmic halves of the aspartate-malate shuttle (aspartate amino-transferase and malate dehydrogenase). The interactions between fumarase and malate dehydrogenase were also investigated by immobilizing one enzyme indirectly through antibodies bound to Sepharose-protein A. Our results are consistent with a model in which maximally four molecules of malate dehydrogenase are bound to one fumarase molecule. This complex is able to bind either citrate synthase or aspartate aminotransferase. We propose that these enzymes bind alternatively, in order to allow the cell to perform citric acid cycle or shuttle reactions, according to its needs. The physiological meaning and implications on the regulation of metabolism of the existence of a large citric acid cycle/malate-aspartate shuttle multienzyme complex are discussed.

Animals↗
PubMed1977

A new purification procedure for fumarase based of affinity chromatography. Isolation and characterization of pig-liver fumarase.

A new procedure has been developed for the isolation of fumarase (EC 4.2.1.2). It is described for the purification of pigheart and liver enzyme. Pyromellitic acid has been covalently coupled to Sepharose-4B with diaminopropanol as spacer arr. When a dialysed 0.55 saturated ammonium sulphate precipitate is applied to the column, in Tris-acetate buffer, pH 7.3, fumarase remains quantitatively bound. It is eluted by competition, together with a few other proteins, by the natural product L-malate. Malate is removed from the eluate by dialysis. After this highly efficient purification step the enzyme is very easily crystallized. The final yield by 67% for both pig heart and liver preparations. The specific activity of fumarase purified from both tissues is found to be the same. Polyacrylamide gel electrophoresis in dodecylsulphate shows one single band corresponding with a subunit molecular weightof 48500. A single band is also obtained by electrophoresis in acid urea. This new procedure based on biospecific affinity chromatography allows a fast and easy preparation of gram quantities of fumarase.

Amino Acids↗
PubMedDate not supplied

Not the presence but the synthesis of HSPS correlates with thermotolerance in a fibrosarcoma MO4 cell-line.

This study reports the induction of heat shock proteins (hsps) and thermotolerance in a MO4 cell line. An enhanced synthesis of hsp68, hsp70 and hsp90 was observed. After 6 hrs, the synthesis of hsp68 and hsp70 decreased to the control value. Hsp90 synthesis was absent after 10 hrs. However, hsps were found to be stable for longer periods of time (more than 48 hrs). A coupled study of hsps and SF demonstrated that an induction of hsps were followed by a change in the slope of the survival curve. Thermotolerance, as expressed by the observed SF after a second heating, is only present during the first 4 hrs and decayed between 4 and 8 hrs. We could not find a correlation between the presence of hsps and thermotolerance, but only between the synthesis of hsps and thermotolerance in MO4 cells.

Animals↗