Pig liver microsomes

Stndies of the antoxidation of carotenoids in liposomal suspensions have also been performed since liposomes can mimic the environment of carotenoids in vivo. Kim et al. stndied the antoxidation of lycopene," P-carotene," and phytofluene" " in liposomal snspensions and identified oxidative cleavage compounds. Stabilities to oxidation at room temperature of various carotenoids incorporated in pig liver microsomes have also been studied." The model took into account membrane dynamics. After 3 hr of reactions, P-carotene and lycopene had completely degraded, whereas xanthophylls tested were shown to be more stable. 

The researeh on dehydroepiandrosterone (DHEA) is limited beeause of the laek of radiolabeled metabolites. Robinzon et al. [126] showed that, using pig liver mierosomes, the radiolabeled metabolites of DHEA can be prepared in stable, pure form for bioehemical smdies. They utilized pig liver microsomal (PLM) fractions to prepare pH]-labeled 7a-hydroxy-DHEA (7a-OH-DHEA), 7[3-hydroxy-DHEA (7P-OH-DHEA), and 7-oxo-DHEA substrates from 50 pM [1,2,6,7-3H]DHEA. The metabolites were separated by silica gel PLC plates using ethyl aeetate-hexane-gla-eial aeetic acid (18 8 , v/v) as the mobile phase, extracted with ethyl aeetate, and dried under a stream of nitrogen. The purity of markers was determined with the use of TLC and GC/MS. 

Rendic, S., Ruf, S., Weher, P. and Kajfez, F. (1984). Cimetidine and ranitidine Their interaction with human and pig liver microsomes and with purified cytochrome P-450. Eta J. Drug Metab. Pharmacokinet. 9 195-200. 

Hajjar NP, Hodgson E. 1982. Sulfoxidation of thioether-containing pesticides by the flavin-adenine dinucleotide-dependent monooxygenase of pig liver microsomes. Biochem Pharmacol 31 745-752. 

The indomethacin-hydrolyzing enzyme from pig liver microsomes was purified and partially characterized [60]. The enzyme was found to be different from known pig liver esterases, since it did not hydrolyze naphth-l-yl-acetate and (4-nitrophenyl)acetate, which are typical substrates for these car-boxy lesterases. The amino acid sequence of the enzyme showed high homology with the mouse carboxylesterase isoenzyme ES-male. Human liver car-... 

Garfinkel, D. (1958) Studies on pig liver microsomes. I. enzymic and pigment composition of different microsomal fractions. Arch. Biochem. Biophys. 77, 493-509. 

The same phenomenon was observed for mitraciliatine (10) and the closed ring E alkaloids 14-19, where the percentage metabolism by O-demethylation estimated by formaldehyde production ( 1%) was much less than the degree of total metabolism (25-69%). Nevertheless, both hirsutine and mitraciliatine gave detectable amounts of a compound assumed by TLC analysis to be an 0-(17)-demethyl metabolite, whereas such was not the case with 14-19. Hirsutine and mitraciliatine were also metabolized (to unidentified products) by both rat and guinea pig liver microsomes, which did not metabolize alkaloids 4-6, 9, and 11-13. 

Monocrotaline (169) Guinea pig liver microsomes (Monocrotaline A -oxide) (170) (-) 170... 

The metabolism of atropine (227) by rat and guinea pig liver microsomes has been studied (197-199). French workers noted the formation of nora-tropine (229), apoatropine (233), and a phenolic metabolite formulated as the ortho-phenol 230 (197, 198) by liver microsomes from the rat, and they reported that hydrolysis of the ester function of 227 did not occur with enzymes from this source (197, 198). The structure of 229 was determined by TLC comparisons of the metabolite with an authentic sample and by correlation of the formation of the metabolite with the release of formaldehyde in the incubation mixture. The structure of 233 was deduced by TLC and UV spectral comparisons of isolated metabolite with authentic sample, and the phenol 230 was identified by TLC color reactions and by comparison with a phenolic sample obtained by Udenfried oxidation of atropine. In the absence of more definitive data on the phenolic products of this reaction, the structure 230 proposed for the phenolic metabolite of atropine... 

FMO was first purified to homogeneity from pig liver microsomes and subsequently from the livers of several other mammalian species. It is a highly lipophilic protein containing FAD as the only flavin, with a monomeric molecular mass of 56,000 per mole of FAD. Investigations to date indicate that there are at least five, or possibly six, forms, named FMOl through FM06. 

C. Le Page, M. Schaefer, A. M. Batt, and G. Siest, Dev. Biochem., 13,363 (1980). QSAR in a Series of Secondary Amines Derived from Perhexilline Maleate with Purified Phenobarbital-Induced Pig Liver Microsomal Cytochrome P-450. 

Fhllllpson, J.D., Banda, S S., Gorrod, J.W. 1976 Metabolic N-Oxldatlon of Atropine, Hyosclne, and The Corresponding Nor-Alkalolds by Guinea-Pig Liver Microsomal Preparations. J. Riarm. Pharmacol. 28 687-691. 

Table I. Effect of Deficiency on Electron Transport Components and Drug Enzymes in Guinea Pig Liver Microsomes...

Others such as pig liver microsomal FAD-containing monooxygenase have to be isolated from tissue with very low yields141 or like hydrocarbon monooxygenase from Pseudomonas oleovorans 12 131 require several protein components and cofactors, substantially limiting the use of these enzymes for the production of oxidized sulfur compounds. 

Figure 1. Proposed biotransformation pathway of furazolidone by pig liver microsomes (52).

Sono, H., Y. Sonoda, and Y. Sato (1991). Purification and characterization of cytochrome P-45014DM (lanosterol 14a-demethylase) from pig liver microsomes. Biochim. Biophys. Acta 1078, 388-394. 

Smyser, B. P. and Hodgson. E. (1985). Metabolism of phosphorus-containing compounds by pig liver microsomal FAD-containing monooxygenase, Biochem. Phatvuicol 34,1145-1150. 

Cytochrome P450 Guinea pig Liver microsomes 1.45 nmol/mg protein 7... 

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