Untitled

Frezza

et al. 1989

Biochemical Journal

This study investigated whether the same cytochrome P-450 (P-450) isoenzymes were inducible in cultures of chick-embryo hepatocytes as in the liver of chicken embryos. We purified two isoenzymes of cytochrome P-450 from the livers of 17-day-old-chick embryos: one of molecular mass approx. 50 kDa induced in vivo by the phenobarbital-like inducer glutethimide, and the second of approx. 57 kDa induced by 3-methylcholanthrene. Rabbit antiserum against the 50 kDa protein inhibited benzphetamine demethylase activity in hepatic microsomes (microsomal fractions) from glutethimide-treated chick embryo. Antiserum to the 57 kDa protein inhibited ethoxyresorufin de-ethylase activity in hepatic microsomes from methylcholanthrene-treated chick embryo. Cultured chick hepatocytes were treated with chemicals known to induce isoenzymes of P-450 in rodent liver. The induced P-450s were quantified spectrophotometrically and characterized by immunoblotting and enzyme assays. From these studies, chemical inducers were classified into three groups: (i) chemicals that induced a P-450 isoenzyme of 50 kDa and increased benzphetamine demethylase activity: glutethimide, phenobarbital, metyrapone, mephenytoin, ethanol, isopentanol, isobutanol, lindane, lysodren; (ii) chemicals that induced a P-450 isoenzyme of 57 kDa and increased ethoxyresorufin de-ethylase activity: 3-methylcholanthrene and 3,3',4,4'-tetrachlorobiphenyl; and (iii) the mono-alpha-substituted 2,3',4,4',5-pentabromobiphenyl, which induced both proteins and both activities. The immunochemical data showed that chick-embryo hepatocytes in culture retain the inducibility of glutethimide- and methylcholanthrene-induced isoenzymes of P-450 that are inducible in the liver of the chicken embryo.

Section: Fig 3 Immunoblots Of Microsomes From Induced Hepatocyte Cumentioning

confidence: 90%

Immunochemical detection of different isoenzymes of cytochrome P-450 induced in chick hepatocyte cultures

Frezza

et al. 1989

Biochemical Journal

European Journal of Biochemistry

“…Among these are phenobarbital [15, 161, several polychlorinated biphenyls [30] (this article), ychlordane [44], trans-stilbeneoxide [44], 1,l -dichlorophenyl-2,2-dichloroethylene [45], 2-diethylaminoethyl-2,2-diphenylvalerateHC1 (SKF-525A) [44].…”

Section: Discussionmentioning

confidence: 99%

Induction of cytochrome P‐450 b, e‐type isozymes by polychlorionated biphenyls in rat liver

Scholte

Velde

Groot

et al. 1985

We have studied the induction of cytochrome P-450 b,e-type antigen and mRNA by phenobarbital, 4,4'-dichlorobiphenyl and 2,4,5,2',4',5'-hexachlorobiphenyl in male Wistar rat liver. Chronic treatment of rats with 4,4'-dichlorobiphenyl leads to a relatively slow, 20-fold increase in the cytochrome P-450 b,e-type antigen level and to an equivalent increase in the concentration of the corresponding mRNA. Treatment of rats with phenobarbital or 2,4,5,2',4',5'-hexachlorobiphenyl results in a faster and more pronounced increase of cytochrome P-450b,e-type antigen and mRNA levels. Analysis of clones from cDNA banks showed that two types of sequences are induced by phenobarbital corresponding to cytochrome P-450 b and cytochrome P-450c respectively.2,4,5,2',4',5'-Hexachlorobiphenyl appears to induce primarily a cytochrome P-45Ob-type sequence. The implications of these results for the study of the mechanism of induction are discussed. . Dependent on the rat strain used, a variety of alleles is expressed. All of the isozymes of this class are immunologically indistinguishable but can be identified by chromatographic methods [16, 231. In order to elucidate the mechanism of induction, information about the number and structure of the genes involved is necessary. In recent years several groups have succeeded in the molecular cloning of cDNA of messenger RNAs coding for isozymes induced by phenobar- The study presented here describes the induction of cytochrome P-450 b,e-type isozyines and corresponding mRNAs by polychlorinated biphenyls. Polychlorinated biphenyls form a group of related substances which can be divided into subgroups on the basis of their induction properties. Some polychlorinated biphenyl congeners are strong inducers of cytochrome P-45Oc whereas others induce only cytochrome P-450 b,e-type antigen [29, 301. The molecular basis for this is not understood but probably relates to the properties of the receptor systems involved. We have studied the isozymes and mRNAs induced in male Wistar rat liver by 4,4'-dichlorobiphenyl and 2,4,5,2',4',5'-hexachlorobiphenyl.We report here the molecular cloning of sequences induced by 2,4,5,2',4',5'-hexachlorobiphenyl and their comparison to sequences induced by phenobarbital. MATERIALS AND METHODS A iiinialsMale Wistar rats (200 g) were obtained from a local breeding farm. Sprague-Dawley rats and New Zealand White rabbits (3 kg) were from T N O (Rijswijk). All animals were kept under a 12-h day-/night regime at 22°C and 60% relative humidity. Rats were fed standard chow and tap water ad libitum Rats were starved during 18 h before sacrifice. InductionDetails of the induction regime are stated in the legends of the figures. Phenobarbital was administered as a 0.1% solution in the drinking water. 2,4,5,2',4',5'-Hexachlorobi-

“…( 1 2 ; R =H,MeorPh) in reactions using sulphonamides as the chiral auxiliaries. 8 The addition sequence used in Method D was (i) (l), (ii) ArCHO, (iii) Ti (OPr'), and (iv) Et,Zn. This should lead to the initial formation of the chiral Schiff's base (6), which would react further with Ti(OPri)4 to give (11).…”

mentioning

confidence: 99%

Asymmetric ethylation of aromatic aldehyde by diethylzinc in the presence of chiral auxiliaries derived from (S)-[4-HOC6H4CH2CH(NH2)CPh2OH]

Wardell

Worayingyong

1995

Appl. Organomet. Chem.

A comparative study has been carried out on enantioselective ethylation of aromatic aldehydes (ArCHO) by diethylzinc (EGZn) in the presence of catalytic amounts of (S)-[4-HOC,H4CH,CH(NH2)CPh,0H](1) or chiral auxiliaries derived from (1). Various procedures have been adopted; these involved (i) different sequences of addition of the reagents ArCHO, Et,Zn and (l), and (ii) use of titanium(1-V)isopropoxide [Ti(OPr'),] or the boranetetrahydrofuran addition compound (BH, THF) as additional reagents. In all but one of the procedures adopted, (S)-ArCH(0H)Et was selectively formed; enantiomeric excess values up to 87% were obtained.