The substrate specificity of rat liver microsomal glutathione transferase toward glutathione has been examined in a systematic manner. Out of a glycyl-modified and eight gamma-glutamyl-modified glutathione analogues, it was found that four (glutaryl-L-Cys-Gly, alpha-L-Glu-L-Cys-Gly, alpha-D-Glu-L-Cys-Gly, and gamma-L-Glu-L-Cys-beta-Ala) function as substrates. The kinetic parameters for three o...

Conditions have been developed for the solubilization of hepatic microsomal carnitine acyltransferase activity in good yield, with excellent long-term stability and with retention of malonyl-CoA sensitivity. Solubilized microsomal carnitine acyltransferase activity can be separated into malonyl-CoA-sensitive and -insensitive activities either by gel filtration on Superdex 200 or by anion-exchan...

The activation of microsomal glutathione S-transferase in oxidative stress was investigated by perfusing isolated rat liver with 1 mM tert-butyl hydroperoxide (t-BuOOH). When the isolated liver was perfused with t-BuOOH for 7 min and 10 min, microsomal, but not cytosolic, glutathione S-transferase activity was increased 1.3-fold and 1.7-fold, respectively, with a concomitant decrease in glutath...

The transverse distribution of enzyme proteins and phospholipids within microsomal membranes was studied by analyzing membrane composition after treatment with proteases and phospholipases. Upon trypsin treatment of closed microsomal vesicles, NADH- and NADPH-cytochrome c reductases as well as cytochrome b5 were solubilized or inactivated, while cytochrome P-450 was partially inactivated. When ...

1. The distribution of DPN and DPNH pyrophosphatases and DPNase in centrifugally prepared fractions of organs of several species of animals is reported. 2. A DPNH pyrophosphatase was found in the soluble fraction of pigeon and of rabbit liver. This enzyme did not split DPN but accounted for over 50 per cent of the DPNH pyrophosphatase activity of the whole homogenates. 3. All the organs tested,...

Purified rat liver ATP citrate lyase is shown to bind to the microsomal fraction of rat liver. Under the same conditions the enzyme does not bind significantly to the mitochondrial fraction or to the outer membrane prepared from the mitochondrial fraction. The binding component of the microsomal fraction is further identified as the endoplasmic reticulum, and a protein component of the membrane...

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.

The consumption of diets formulated with Cruciferae vegetables, e.g., cauliflower, cabbage, and Brussels sprouts, has been shown to result in a stimulation of the intestinal and hepatic microsomal enzyme systems in rats. This study was designed to determine if this increase in intestinal and hepatic microsomal enzyme activity affected the hepatic response to polybrominated biphenyls (PBB). Afte...

The properties of the microsomal vitamin K-dependent carboxylase from the livers of the adult ox and dicoumarol-treated calf were investigated. The enzymes from both sources utilized glutamic residues of synthetic peptides as substrates and could be solubilized with Triton X-100 similarly to the enzyme from vitamin K-deficient rat liver. Under the optimal assay conditions, the microsomes from c...

Problem statement: Our previous research has shown that mitochondrial ATPase may have a role in the action of dopaminergic D2 receptors. It is therefore, thought of interest to investigate the effect of bromocriptine, sulpiride or their combination on the mitochondrial and microsomal ouabain sensitive and ouabain insensitive Na/K-ATPase in the liver of rats. Approach: In vivo treatment was carr...