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H Dreyfus

Publications and source records attributed to H Dreyfus.

At least 91 records · Page 5Linked to original sources
PubMed1982

Topographic distribution of enzymes synthesizing phosphatidylcholine and phosphatidylethanolamine in chicken brain microsomes.

The localization of phosphatidylethanolamine and phosphatidylcholine biosynthetic enzymes within the transverse plane of chicken brain microsomes was investigated by using proteases (trypsin and pronase) and neuraminidase. Treatment of intact microsomes with the proteases inactivated the phosphocholine transferase completely and the ethanolamine phosphotransferase only slightly. This latter enzyme was, however, completely inactivated when deoxycholate-treated microsomes were exposed to proteases. Treatment of intact microsomes with neuraminidase had no effect on both phosphotransferases, although 65% of the sialic acid of sialoglycoproteins and 37% of that of gangliosides were removed. With deoxycholate-disrupted microsomes nearly all sialic acid from the sialoglycoproteins and about 70% of that of gangliosides were released. In parallel, the phosphoethanolamine transferase was 90% inactivated. It is suggested that phosphocholine transferase is localized on the outer face of the microsomal vesicle, whereas the phosphoethanolamine transferase could be a sialoglycoprotein, possibly situated on the inner face of the vesicle, or perhaps a transmembrane protein.

Animals↗
PubMed1981

[Role of sialo compounds in choline uptake by synaptosomes].

Two kinetic mechanisms are responsible for the uptake of choline in Rat brain synaptosomal fractions with different affinity towards the substrate (high affinity mechanism: Km 5.1 microM, Vmax 44 pmol/mg prot/min.; low affinity mechanism: 35.7 microM, Vmax 286 pmol/mg prot/min). The treatment of synaptosomal fractions with neuraminidase (15 min. at 37 degrees C) followed by 1 min. incubation with various concentrations of [14C] choline reduces the uptake in parallel with the disappearance of the high affinity mechanism (Km 202.2 microM, Vmax 119 pmol/mg prot/min.), without influencing the synthesis of acetylcholine.

Acetylcholine↗
PubMed1981

Chloroquine-induced accumulation of gangliosides and phospholipids in skeletal muscles. Quantitative determination and characterization of stored lipids.

High doses of the lysosomotropic drug chloroquine result in lipid storage in many organs in animals. We used miniature pigs, type Göttingen, to study the lipid accumulation in skeletal muscle after chloroquine intoxication for more than 200 days. The lipids of the quadriceps muscle in intoxicated and in age-matched control pigs were characterized and determined. The lipid storage was larger in skeletal muscle than in any other organ of the intoxicated pigs. The concentration of phospholipids was increased threefold, acidic phospholipids relatively more than neutral ones. The lysosome-specific acidic phospholipid bis(monoacylglyceryl)phosphate content was almost 50-fold larger in the intoxicated pigs than in the controls. Cholesterol was increased slightly more than the phospholipids, but there was no particular accumulation of cholesteryl esters, which has been shown to occur in the liver. For the first time a storage of gangliosides, relatively more pronounced than of other lipids, was demonstrated in skeletal muscle in the drug-induced lipidosis. The concentration of total gangliosides was increased 10--15-fold, and the pattern of gangliosides showed some distinct changes resulting in at least a 100-fold increase in the concentration of ganglioside GM2 (II3NeuAc-GgOse4Cer).

Animals↗