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B Nasser

Publications and source records attributed to B Nasser.

4 recordsLinked to original sources

Interactions of the mitochondrial membrane rat liver D-3-hydroxybutyrate dehydrogenase with glass beads during adsorption chromatography. Relationships with the activation of the enzyme by phospholipids.

D-3-Hydroxybutyrate dehydrogenase (BDH) is an NAD(+)-dependent dehydrogenase of the mitochondrial inner membrane involved in the energetic balance between the liver and peripheral organs in mammals. It allows the conversion of ketone bodies (acetoacetate and D-3-hydroxybutyrate) and it is one of the best documented lipid-requiring enzymes with a dependence on lecithins. After release of proteins from the membrane by phospholipase A2 treatment of salt-treated mitochondria, the rat liver enzyme is absorbed on controlled-pore glass beads. After batch washing, the enzyme, devoid of lipids (apoBDH), is specifically eluted at pH 8.05-8.15 with a 0.1 M Tris-1 M LiBr buffer under reducing conditions (5 mM dithiothreitol). It appears that during BDH absorption, the glass beads mimic the phospholipid surface of biomembranes.

Animals

[Effects of synthetic bioactive lipids on the activity of D-beta-hydroxybutyrate dehydrogenase, a membrane enzyme].

The structural requirements of lecithins analogs for purified D-beta-hydroxybutyrate dehydrogenase activation have been studied with chemically defined phospholipids. It appears that the trimethylamine group of choline can be changed by a pyridinium group. On the other hand, the decrease of density of the positive charges on the liposomes surface obtained by dilution of such bearing molecules with negative or non charged phospholipids increases the enzyme reactivation. Finally, the PAF acether, a lipid mediator, is able to reactivate the enzyme in similar conditions as these obtained with mitochondrial phosphatidylcholines.

Chemical Phenomena

Phospholipid polar head specificity of D-3-hydroxybutyrate dehydrogenase activation studied by new synthetic phospholipids and analogues.

D-3-hydroxybutyrate dehydrogenase, an inner-mitochondrial enzyme responsible for the interconversion of two ketone bodies, is a well known phospholipid dependent enzyme. Newly synthesized phospholipid analogues were used to study the structural requirement for lipid activation of the purified enzyme. A positive charge on the polar head is required but must be at the surface of lipid vesicles. In contrast the maximum velocity and the Michaelis constant values are not strongly dependent on the nature of the zwitterionic phospholipid polar head.

Animals