title: Subfractionation of smooth microsomes from rat liver.
abstract: Total smooth microsomes from rat liver isolated on a Cs(+)-containing sucrose gradient were concentrated and subsequently fractionated by zone centrifugation on a stabilizing sucrose gradient. The prerequisite for fractionation is to prepare total smooth microsomes in a nonaggregated condition, as well as to utilize a procedure which counteracts enzyme inactivation. The median equilibrium density of the various smooth microsomal vesicles ranges from 1.10 to 1.18. The phospholipid/protein ratio is identical in all subfractions, but cholesterol, on a PLP basis, is enriched in the subfractions with the highest sedimentation velocity. The enzyme distribution pattern reveals a pronounced heterogeneity. A number of NADH- and NADPH-oxidizing enzymes are concentrated in the upper part of the gradient and exhibit a certain degree of separation from G6Pase. Mg(++)-ATPase and AMPase are enriched in the lower part of the gradient. No specific enrichment of newly synthesized NADPH-cytochrome c reductase activity occurs in any of the subfractions after phenobarbital treatment. These data demonstrate that smooth microsomes, by adequate fractionation procedure, can be separated into subfractious of heterogeneous composition.
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D002458:Cell Fractionation; D002462:Cell Membrane / Q000032:analysis; D002499:Centrifugation, Density Gradient; D002501:Centrifugation, Zonal; D002784:Cholesterol / Q000032:analysis; D004579:Electron Transport; D003576:Electron Transport Complex IV / Q000032:analysis; D005374:Filtration; D005952:Glucose-6-Phosphatase / Q000032:analysis; D005990:Glycerol / Q000378:metabolism; D008099:Liver / Q000166:cytology*; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D008995:Monoamine Oxidase / Q000032:analysis; D009243:NAD / Q000032:analysis; D009249:NADP / Q000032:analysis; D010634:Phenobarbital / Q000494:pharmacology; D010743:Phospholipids / Q000032:analysis; D010744:Phosphoric Monoester Hydrolases / Q000032:analysis; D011506:Proteins / Q000032:analysis; D012313:RNA / Q000032:analysis; D051381:Rats; D013997:Time Factors; D014316:Tritium
chemical_list: D010743:Phospholipids; D011506:Proteins; D009243:NAD; D014316:Tritium; D009249:NADP; D012313:RNA; D002784:Cholesterol; D008995:Monoamine Oxidase; D003576:Electron Transport Complex IV; D010744:Phosphoric Monoester Hydrolases; D005952:Glucose-6-Phosphatase; D000251:Adenosine Triphosphatases; D005990:Glycerol; D010634:Phenobarbital