Enzymes microsomal

PGH2 + Enzyme (microsomal prostaglandin E synthase, mPGES) PGE2... 

Evidence for the involvement of a single, multifunctional enzyme— microsomal glucose-6-phosphatase—in the above variety of hydrolytic and synthetic reactions has been summarized recently by the author (10) as follows ... 

Ethanol is not metabolized by cytochrome P-450 enzymes (microsomal drug-metabolizing systems, or MEDS). However, it is metabolized to a certain extent by the microsomal ethanol-oxidizing system (MEOS). 

These studies can be done with liver microsomes, hepatocytes, and recombinant preparations of CYP enzymes. Microsomes are membrane fragments prepared from homogenized liver, while hepatocytes are liver cells that have been collected from collagenase-perfused liver. These are then cocultured with collagen, and fibroblasts... 

Microsomal fractions contain 3a- and 3 -hydroxysteroid dehydrogenases which do not appear to be derived from cytosol [171]. Thus, microsomal 3a-hydroxysteroid dehydrogenase preferentially utilized [4B- H]NADH instead of [4A- H]NADPH preferred by the cytosolic enzyme. Microsomal 3)3-hydroxysteroid dehydrogenase was inactive toward ethanol, and thus is not an active component of alcohol dehydrogenase [172]. These dehydrogenases were active with ,9, C21, C24 and C27... 

Without the enzyme microsomal triglyceride transfer protein (MTP), hepatic triglycerides cannot be transferred to apoB-100. Patients with dysfunctional MTP fail to make any of the apoB-containing lipoproteins (VLDL, IDL, or LDL). MTP also plays a key role in the synthesis of chylomicrons in the intestine, and mutations of MTP that result in the inability of triglycerides to he transferred to either apoB-100 in the liver or apoB-48 in the intestine prevent VLDL and chylomicron production and cause the genetic disorder abetalipoproteinemia. 

BIOACCUMULATION bioconcentration in fish will occur, however fish will rapidly metabolize it by the action of the enzyme microsomal oxidase... 

In vitro studies involving human metabolism of pharmaceuticals have been routine for many years and are gaining popularity for agricultural chemicals as well (Hodgson, 2003). This effort is aided by the increased availability of human tissues and recombinant human enzymes. Microsomes, S9,... 

Suneja SK, Wagle DS, Ram GC. Effect of oral administration of T-2 toxin on glutathione shuttle enzymes, microsomal reductase and lipid peroxidation in rat liver. Toxicon. 1989 27(9) 995 1001. 

Figure 12.62 Biodegradation of atrazine (G-SH = reduced glutathione, enzyme = microsomal monoxidase).

Enzyme Microsomal (S-9) preparation supplemented with cofactors. % Survivors pol Ai /% survivors p>ol... 

Wagle, S. R. Studies on biosynthesis of insulin by pH-5 enzymes-microsome system from fetal dog pancreas. Biochim. et Biophys. Acta 95, 180 (1965). 

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