Purification and properties of rat liver microsomal stearyl coenzyme A desaturase.

A requirement for lipids by the microsomal stearyl coenzyme A desaturase.

Hen liver microsomes, when extracted with aqueous acetone, lose their ability to desaturate stearyl coenzyme A to oleate. The desaturase activity of these particles is partially restored by addition of lipid micelles prepared from microsomal lipid. Fractionation of the microsomal lipid yields fractions which are tested for their ability to restore the desaturase activity. A mixture of phospholi...

The binding of cytochrome b 5 to liver microsomes.

The 40-44 hydrophobic peptide segment, present in cytochrome bS obtained by nonhydrolytic means, but absent from lipase or trypsin-extracted cytochrome bg, has been found to be required for the binding of a loto 20-fold molar excess of cytochrome bs to liver microsomes. At saturation, the bound cytochrome bs constitutes nearly 20% of the total protein of the vesicle preparations. This extra bou...

Degradation of stearoyl-coenzyme A desaturase: endoproteolytic cleavage by an integral membrane protease.

Stearoyl-coenzyme A desaturase (SCD) is a key regulator of membrane fluidity, turns over rapidly, and represents a prototype for selective degradation of resident proteins of the endoplasmic reticulum. Using detergent-solubilized, desaturase-induced rat liver microsomes we have characterized a protease that degrades SCD. Degradation of SCD in vitro is highly selective, has a half-life of 3-4 h,...

Dietary effects on stearyl coenzyme A desaturase in Morris hepatomas.

The purification and properties of microsomal palmitoyl-coenzyme A synthetase.

The isolation and purification of palmitoyl-CoA synthetase from rat liver microsomes is described. Several methods suitable for enzyme assay are described. The general properties and kinetic parameters of the purified enzyme were determined and are discussed in relationship to microsomal fatty acid activation.