共查询到20条相似文献,搜索用时 78 毫秒
1.
The involvement of cytochrome b5 in different cytochrome P450 monooxygenase and palmitoyl CoA desaturase activities in microsomes from insecticide-resistant (LPR) house flies was determined using a specific polyclonal antiserum developed against house fly cytochrome b5. Anti-b5 antiserum inhibited the reduction of cytochrome b5 by NADH-cytochrome b5 reductase. The antiserum also inhibited palmitoyl CoA desaturase, methoxycoumarin-O-demethylase (MCOD), ethoxycoumarin-O-deethylase (ECOD), and benzo[a]pyrene hydroxylase (aromatic hydrocarbon hydroxylase, AHH) activities. However, methoxyresorufin-O-demethylase (MROD) and ethoxyresorufin-O-deethy-lase (EROD) activities were not affected by this antiserum. These results demonstrate that cytochrome b5 is involved in fatty acyl CoA desaturase activities and in certain cytochrome P450 monooxygenase activities (i.e., MCOD, ECOD, and AHH) in LPR house fly microsomes. Other cytochrome P450 monooxygenase activities (i.e., MROD and EROD) may not require cytochrome b5. The results suggest that cytochrome b5 involvement with cytochrome P450 monooxygenase activities is dependent upon the cytochrome P450 isoform involved. © 1994 Wiley-Liss, Inc. 相似文献
2.
A Dhawan D Parmar M Das P K Seth 《Biochemical and biophysical research communications》1990,170(2):441-447
Distribution of the mixed function oxidases (MFO's) catalyzed by presence of multiple forms of cytochrome P-450 (P-450) was investigated in the neuronal and glial cells of the brain. The neuronal cells exhibited 2-3 fold higher activity of P-450 dependent arylhydrocarbon hydroxylase (AHH), 7-ethoxycoumarin-o-deethylase (ECOD) and 7-ethoxy-resorufn-o-deethylase (EROD) than the glial cells. Pretreatment with phenobarbital (PB) significantly increased (60-85%) the activity of ECOD in neuronal and glial cells, while a 140% increase was observed in neuronal AHH activity. Exposure to 3-methylcholanthrene (MC) resulted in a significant induction of the activity of AHH (102-345%), ECOD (115-150%) and EROD (75-120%) in the neuronal and glial cell preparations. The neurons, in general, exhibited greater sensitivity towards PB and MC induction. The present data indicate the differential sensitivity of these enzymes in neuronal and glial cells which could be used as a model to understand the selective action of certain neurotoxic agents. 相似文献
3.
The activities of 7-ethoxyresorufin-O-deethylase (EROD), 7-pentoxyresorufin-O-deethylase (PROD), 7-ethoxycoumarin-O-deethylase (ECOD) and aromatic hydrocarbon hydroxylase (AHH) were measured in hepatic microsomes from male and female Wistar rats and Syrian golden hamsters in order to probe the basal activity and the inducibility by phenobarbital (PB) and 3-methylcholanthrene (MC) of different P-450 isoenzymes. The basal activities of EROD and ECOD, but not PROD and AHH, were higher in male hamsters than in male rats. No sex-related difference in enzyme activities was observed with hamsters, whereas male rats had a higher ECOD and AHH activity than female rats. Induction by PB led to a 450-fold and 250-fold increase in PROD activity in male and female rat liver microsomes, respectively, while MC had a more pronounced inductive effect on EROD activity in this species. In hamsters, EROD activity was induced by MC but not by PB. Unexpectedly PROD activity in male and female hamster liver microsomes was only moderately induced by PB, the extent being lower than on induction by MC. Therefore, the activity of PROD, which is useful as a specific enzymatic assay for P-450 IIB in the rat liver, cannot be used to probe PB-like inducers in the hamster liver. 相似文献
4.
A Arillo M Bagnasco C Bennicelli F Melodia L Viganò 《Bollettino della Società italiana di biologia sperimentale》1992,68(8-9):543-548
The induction in fish liver of some enzyme activities, and typically of microsomal mixed-function oxidases (MFO), provides the earliest biological warning signal of exposure to pollutants. Our studies provided evidence that the basal levels of cytochrome P-450 and specific MFO activities, such as arylhydrocarbon hydroxylase (AHH) and ethoxyresorufin deethylase (EROD), were strongly influenced by the diet in freshwater fish (Oncorhynchus mykiss). The response of fish liver to a known enzyme inducer, i.e., beta-naphthoflavone, was also affected by the diet, which therefore should be carefully controlled in laboratory studies. Under field conditions MFO activities were significantly enhanced in the liver of O. mykiss kept in polluted river water as well as in the liver of the seawater fish Diplodus annularis collected from a polluted harbour area, as compared to specimens of the same species collected from an unpolluted reference area. 相似文献
5.
Development and characterization of a rainbow trout liver cell line expressing cytochrome P450-dependent monooxygenase activity 总被引:1,自引:0,他引:1
Lucila E. J. Lee Janine H. Clemons Daniel G. Bechtel Sarah J. Caldwell Kyu-Bo Han Maria Pasitschniak-Arts Dick D. Mosser Niels C. Bols 《Cell biology and toxicology》1993,9(3):279-294
A cell line RTL-W1, has been developed from the normal liver of an adult rainbow trout by proteolytic dissociation of liver fragments. RTL-W1 can be grown routinely in the basal medium, L-15, supplemented with 5% fetal bovine serum. In this medium, the cells have been passaged approximately 100 times over an 8-year period. The cells do not form colonies or grow in soft agar. The cultures are heteroploid. The cell shape was predominantly polygonal or epithelial-like, but as cultures became confluent, bipolar or fibroblast-like cells appeared. Among the prominent ultrastructural features of RTL-W1 were distended endoplasmic reticulum and desmosomes. Benzo[a]pyrene was cytotoxic to RTL-W1. Activity for the enzyme, 7-ethoxyresorufin O-deethylase (EROD), which is a measure of the cytochrome P4501A1 protein, increased dramatically in RTL-W1 upon their exposure to increasing concentrations of either -naphthoflavone (BNF) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). With these properties, RTL-W1 should be useful for studying the expression of the cytochrome P450 enzymes and as a tool for assessing the toxic potency of environmental contaminants.Abbreviations AHH
aryl hydrocarbon hydroxylase
- B[a]P
benzo[a]pyrene
- BNF
-naphthoflavone
- CHSE-214
Chinook salmon embryo cells
- CYP
cytochrome P450
- DMSO
dimethyl sulfoxide
- ECOD
7-ethoxycoumarinO-deethylase
- EDTA
ethylenediaminetetraacetic acid
- EROD
7-ethoxyresorufinO-deethylase
- FBS
fetal bovine serum
- HEPES
N-[-hydroxyethyl]piperazine-N-[2-ethanesulfonic acid]
- H4IIE
rathepatoma cells
- PCB
polychlorinated biphenyls
- PHH
planar halogenated hydrocarbons
- TCDD
2,3,7,8-tetrachlorodibenzo-p-dioxin
- TEM
transmission electron microscopy
- TEFs
toxic equivalent factors
- TS
0.05 mM Tris 0.2M sucrose
- RLE
rat liver epithelial cells
- RTL-W1
rainbow trout liver-Waterloo 1 cells 相似文献
6.
The mutagenicity of benzo[alpha]pyrene and 2-aminoanthracene for Salmonella typhimurium TA98 in the plate-incorporation test was studied using liver S9 from untreated and aroclor-1254-treated rats. The induction of liver S9 protein, arylhydrocarbon hydroxylase (AHH), and cytochrome P448/450 was followed with time. There was no change in protein concentrations with induction; AHH and cytochrome levels were increased at 1, 3, 5 and 7 days post Aroclor treatment. Benzo[alpha]pyrene mutagenicity was enhanced with Aroclor treatment while 2-aminoanthracene mutagenicity was depressed. The benzo[alpha]pyrene mutagenicity showed a positive correlation with the levels of AHH and cytochrome on the plate; 2-aminoanthracene showed a negative correlation with activity in induced samples. 相似文献
7.
Zamaratskaia G Zlabek V Chen G Madej A 《Animal : an international journal of animal bioscience》2009,3(8):1124-1132
The present study aimed to evaluate some cytochrome P450 metabolic enzyme activities in hepatic microsomes prepared from entire male pigs (uncastrated pigs), surgically castrated pigs and pigs immunized against gonadotropin-releasing hormone (immunocastrated pigs). The activities of the following enzymes were measured: ethoxyresorufin O-deethylase (EROD, CYP1A1/1A2), methoxyresorufin O-deethylase (MROD, CYP1A2), pentoxyresorufin O-depentylase (PROD, CYP2B), coumarin hydroxylase (COH, CYP2A) and p-nitrophenol hydroxylase (PNPH, CYP2A/2E1). The total cytochrome P450 contents were not affected by either surgical or immunocastration. Hepatic microsomal activities for EROD, PROD, COH and PNPH were lower in entire male pigs compared with surgically castrated and immunocastrated pigs (P < 0.05). Surgically and immunocastrated male pigs were similar with respect to EROD, MROD, PROD and COH activities (P > 0.05), whereas surgically castrated pigs exhibited lower PNPH activity compared with immunocastrated pigs (P = 0.029). The effect of different concentrations of testicular steroids - testosterone, 17β-estradiol, free estrone and androstenone - on enzyme activities was evaluated by in vitro microsomal study. Testosterone at the concentration of 8 pmol/ml inhibited EROD activities and estradiol-17β at the concentration of 1.8 pmol/ml inhibited PROD activities in hepatic microsomes from surgically castrated pigs. The highest concentration of androstenone (7520 pmol/ml) inhibited COH activities, whereas a 42-fold lower concentration of androstenone (180 pmol/ml) stimulated COH activities in surgically castrated pigs. Both free estrone (3.5 pmol/ml) and androstenone (55 pmol/ml) inhibited EROD activities in microsomes from entire male pigs. Stimulation of COH activities by the highest dose of free estrone (18 pmol/ml) was recorded in microsomes from entire male pigs. However, these effects of steroids were not concentration-dependent and the maximum extent did not exceed ±15% variation compared with the controls. There was no inhibition of PNPH activities in the hepatic microsomes from either entire or castrated pigs. In conclusion, we showed that EROD, PROD, COH and PNPH activities were lower in entire male pigs compared with those in surgically and immunocastrated pigs. Direct inhibition by the testicular steroids - testosterone, 17β-estradiol, free estrone and androstenone - was not the primary cause of the reduced enzyme activities. 相似文献
8.
U Lange A Goksyr D Siebers L Karbe 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》1999,123(4):246
Concentrations of total cytochrome P450 and cytochrome P450 1A (CYP 1A) and activities of ethoxycoumarin O-deethylase (ECOD), ethoxyresorufin O-deethylase (EROD) and pentoxyresorufin O-depentylase (PROD) were measured in the liver of prespawning, spawning and postspawning dab (Limanda limanda) from the German Bight. Between all P450-dependent parameters measured significant correlations were found. Generally, during prespawning and spawning season higher values were measured in the liver of males compared to females, but the ratio between sexes changed during spawning time, when concentrations and activities in the liver of males decreased and increased in the liver of females. The activity and the signal-to-noise ratio decrease in the order EROD, ECOD and PROD. This decrease is accompanied by an increase in Km. The findings indicate that the different activities can be attributed to the strongly overlapping substrate specificity and the different enzyme affinities of one enzyme, CYP 1A, towards the three substrates. A biphasic kinetic of ECOD indicates that in addition to CYP 1A a second isozyme catalyses the O-deethylation of ethoxycoumarin in the liver of dab. Interestingly, the ratio between EROD activity and CYP 1A concentration varied seasonally but did not differ significantly between sexes. 相似文献
9.
Three groups of isomeric nitrogen heterocycles, phenylpyridines, phenylimidazoles and pyridylimidazoles were studied in relation to the effect of steric factors on type II binding to cytochrome P-450 and inhibition of aryl hydrocarbon (benzo[a]pyrene) hydroxylase (AHH) activity in hepatic microsomes from phenobarbital(PB)- and β-naphthoflavone(βNF)-induced rats. Type II binding affinity was lower (higher Ks) in compounds with substituents on the carbon adjacent to the nitrogen undergoing ligand interaction than in those where steric hindrance near the nitrogen was minimal. Binding affinities of the compounds as measured by their Ks values, were quite similar in both PB- and βNF-induced microsomes. In PB-induced microsomes, type II binding affinity was generally reflected by the ability of the compounds to inhibit AHH activity. In contrast, most of the compounds evaluated were inactive as AHH inhibitors in βNF-induced microsomes. 相似文献
10.
Variants of the mouse hepatoma cell clone inducible for aryl hydrocarbon (benzo(a)pyrene) hydroxylase (AHH) (EC 1. 14. 14.1) activity and deficient in hypoxanthine guanine phosphoribosyl-transferase (EC 2.4.2.8), and human primary lung carcinoma cell clone noninducible for AHH activity and deficient in thymidine kinase (EC 2.7.1.21) were isolated. The variant lines characterized for AHH inducibility and drug resistant phenotype were utilized to study somatic cell hybrids for the expression of AHH induction by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In two hybrids AHH activity was not expressed. In view of these results we conclude that aryl hydrocarbon hydroxylase activity is suppressed in AHH noninducible human lung carcinoma x AHH inducible mouse hepatoma cell hybrids. 相似文献
11.
Modulation of drug-metabolizing enzymes by extracts of a herbal medicine Evodia rutaecarpa in C57BL/6J mice 总被引:1,自引:0,他引:1
Evodia rutaecarpa is a traditional Chinese medicine used for the treatment of gastrointestinal disorders and headache. To assess the possible drug interactions, effects of methanol and aqueous extracts of E. rutaecarpa on drug-metabolizing enzymes, cytochrome P450 (CYP), UDP-glucuronosyl transferase (UGT), and glutathione S-transferase (GST) were studied in C57BL/6J mice. Treatment of mice with methanol extract by gastrogavage caused a dose-dependent increase of liver microsomal 7-ethoxyresorufin O-deethylation (EROD) activity. In liver, methanol extract at 2 g/kg caused 47%, 7-, 8-, 4-fold, 81% and 26% increases of benzo(a)pyrene hydroxylation (AHH), EROD, 7-methoxyresorufin O-demethylation (MROD), 7-ethoxycoumarin O-deethylation (ECOD), benzphetamine N-demethylation, and N-nitrosodimethylamine N-demethylation activities, respectively. Aqueous extract at 2 g/kg caused 68%, 2-fold, and 83% increases of EROD, MROD, and ECOD activities, respectively. For conjugation activities, methanol extract elevated UGT and GST activities. Aqueous extract elevated UGT activity without affecting GST activity. Immunoblot analyses showed that methanol extract increased the levels of CYP1A1, CYP1A2, CYP2B-, and GSTYb-immunoreactive proteins. Aqueous extract increased CYP1A2 protein level. In kidney, both extracts had no effects on AHH, ECOD, UGT, and GST activities. Three major bioactive alkaloids rutaecarpine, evodiamine, and dehydroevodiamine were present in both extracts. These alkaloids at 25 mg/kg increased hepatic EROD activity. These results demonstrated that E. rutaecarpa methanol and aqueous extracts could affect drug-metabolizing enzyme activities. Rutaecarpine, evodiamine, and dehydroevodiamine contributed at least in part to the increase of hepatic EROD activity by extracts of E. rutaecarpa. Thus, caution should be paid to the possible drug interactions of E. rutaecarpa and CYP substrates. 相似文献
12.
Marie-Hlne Bani Jean-Francois Narbonne Morio Fukuhara Fusao Ushio Larry W. Robertson 《Journal of biochemical and molecular toxicology》1994,9(5):241-248
The effects of a single injection (40 mg/kg) of 4′-trifluoromethyl-2,3,4,5-tetrachlorobiphenyl (CF3) on hepatic cytochrome P-450 monooxygenases were assessed in rat and syrian hamster. The CF3 treatment significantly increased the total amount of cytochrome P-450 in both species. In rats, CF3 treatment caused marked increases in ethoxyresorufin O-deethylase (EROD), arylhydrocarbon hydroxylase (AHH), and testosterone 7α-hydroxylase activities but significantly reduced the activities of benzphetamine N-demethylase (BzND), erythromycin N-demethylase (ErND), testosterone 6β, 16α, and 16β-hydroxylases, and formation of androstenedione. Administration of CF3 to hamsters strongly induced the activities of EROD, AHH, BzND, testosterone 15α, and 16α-hydroxylases, and androstenedione production, whereas ErND, testosterone 6β, and 7α-hydroxylases were decreased. Administration of CF3 to rats induced the CYP1A family proteins and CYP2A1, while CF3 reduced the level of CYP2B1, and, to a lesser extent, of CYP6β2. In hamsters, CF3 treatment significantly induced the CYP1A2, CYP2A1, CYP2A8, and CYP2B1 isozymes, whereas the CYP6β2 level was decreased. The ability of hepatic microsomes to activate aflatoxin B1 and benzo(a)pyrene was elevated by CF3 treatment in hamsters, while activation of aflatoxin B1 was decreased in microsomes from CF3-treated rats. These results showed differences in the CF3-induced pattern of rat and hamster cytochrome P-450 monooxygenases. 相似文献
13.
Using benzo(a)pyrene (BaP) as a probe for aryl hydrocarbon hydroxylase (AHH) activity, differences in mixed-function oxidase (MFO) activity were observed using microspectrofluorimetry in single living cells during long term treatment with 3-methylcholanthrene (3-MC) or carbaryl. Although these two compounds differ in chemical structure, similar effects were observed in 3T3 cell populations. The results suggest that the two compounds activate the same enzymatic system and that individual cells of a supposed homogeneous cell population are not equally sensitive to xenobiotics, i.e. subpopulations were observed which have differences in AHH activity. 相似文献
14.
Effect of Plasmodium berghei infection and chloroquine on the hepatic drug metabolizing system of mice 总被引:1,自引:0,他引:1
P Srivastava L M Tripathi S K Puri G P Dutta V C Pandey 《International journal for parasitology》1991,21(4):463-466
The hepatic microsomal mixed-function oxidase (MFO) system was markedly impaired during Plasmodium berghei infection in mice. Cytochrome P-450 and other mono-oxygenases, viz. aniline hydroxylase, aminopyrine-N-demethylase and benzo(a)pyrene hydroxylase, were significantly decreased while microsomal heme showed a four-fold increase at peak parasitemia (greater than 50%). Oral treatment with chloroquine (16 mg kg-1 body wt for 4 days) of P. berghei-infected mice cleared the parasitemia within 72 h and almost normalized the altered levels of MFO indices, a week after cessation of treatment. The findings were further supported by the isoenzymic profile and drug-binding properties of terminal mono-oxygenase, cytochrome P-450. 相似文献
15.
Lionel Gil Hernan Vasquez Miriam Orellana James Selkirk Finn Wold Henry Strobel 《Molecular and cellular biochemistry》1988,79(1):5-16
A liver cytochrome P-450 isozyme has been purified to homogeneity from protein-energy malnourished rats induced with -naphthoflavone (-NF). The purification steps included chromatography on DEAE-Sephadex-A-25, DEAE-cellulose (DE-53), hydroxylapatite (HA) and carboxymethyl-sephadex (CM) columns. The reduced carbon monoxide difference and absolute spectra showed a Soret peak at 446.5 nm. The wavelength maxima for the oxidized and reduced spectra were at 416 and 408 nm, respectively. Cytochrome P-446 appears to have a predominantly low spin ferric iron, migrates as a single band of molecular weight 56000 in sodium dodecyl sulfate polyacrylamide gels and has a specific content of 14 nmol/mg of protein. P-446 oxidized various substrates at different rates in a reconstituted system with NADPH-cytochrome P-450 reductase and dilauroylphosphatidylcholine. In this system turnover rates for benzo[]pyrene, testosterone and benzphetamine oxidation were: 81.10; 1.85 and 1.42 nmoles product/min/nmol P-446 respectively. While NH2 terminal amino acid sequence analysis of 18 of the first 20 residues suggests that the cytochrome P-446 isolated from malnourished rats is identical with form c, the catalytic activities suggest that this isozyme may be a more effective or efficient catalyst for some substrates.Abbreviations -NF
-napthoflavone
- SDS-PAGE
Sodium Dodecyl Sulfate polyacrylamide gel electrophoresis
- 3-MC
3-Methyl Cholanthrene
- PEG
Poly Ethylene Glycol
- DTT
Dithiothreitol
- PMSF
Phenyl Methyl Sulfonylfluoride
- EDTA
disodium ethylenediaminetetraacetate
- NADPH
reduced nicotinamide adenine dinucleotide phosphate
- P-450
cytochrome P450, PB-1, PB-4, PB-5 and P-450 isozymes purified from phenobarbital induced rat liver
- HPLC
High Pressure Liquid Chromatography
- B[]P
benzo[]pyrene
- CM
Carboxymethyl Sephadex
- PTH-amino acid
phenylthiohydantoin amino acid, Cytochrome P-450 EC 1.14.14.1, NADPH Cytochrome P-450 (c) reductase ED 1.6.2.4 相似文献
16.
17.
Combined treatment of male Syrian golden hamsters with the synthetic estrogen diethylstilbestrol (DES) and 7,8-benzoflavone (7,8-BF) gives rise to a high incidence of hepatocellular carcinomas, whereas no such tumors are formed with DES alone nor with 7,8-BF alone. To determine whether alterations in DES metabolism may account for the observed hepatocarcinogenicity, we have studied the effect of pretreatment with 7,8-BF alone, DES alone and 7,8-BF plus DES on the levels of hepatic P-450 and cytochrome b5, on the activities of various P-450 isoenzymes and on microsomal DES metabolism. Hepatic P-450 content was significantly increased after pretreatment with 7,8-BF and decreased after DES, while combined pretreatment led to levels similar to those in untreated control animals. Hepatic cytochrome b5 was also elevated in 7,8-BF-treated hamsters; DES pretreatment had no effect, and combined pretreatment led to a slight increase. Four different substrates were used to probe P-450 isoenzyme activity. Aryl hydrocarbon hydroxylase (AHH), 7-ethoxycoumarin-O-deethylase (ECOD), 7-ethoxyresorufin-O-deethylase (EROD) and 7-pentoxyresorufin-O-dealkylase (PROD) were all elevated after 7,8-BF-pretreatment, while DES led to a decrease in these activities with the exception of AHH, where a transient increase which was observed after 8 and 20 weeks of pretreatment was back to control levels after 32 weeks. Combined pretreatment with 7,8-BF and DES led to an intermediate response (slight increase) with AHH, EROD and PROD, but not with ECOD, where a full induction comparable with that observed after 7,8-BF alone was elicited. In spite of the modulation of enzyme levels and activities observed after the various pretreatments, the metabolism of DES in microsomes from pretreated animals was virtually identical with that from controls. Therefore it is concluded that modulation of hepatic DES metabolism is not the reason for the observed hepatotumorigenicity; instead, it is speculated that 7,8-BF is the carcinogenic agent in this tumor model, and DES may act as a promotor. 相似文献
18.
Akihiko Nakama 《Cytotechnology》1999,31(1-2):205-211
The in vitro cellular functions of differentiated cells are influenced by culture conditions. Effects of several extracellular
matrices (ECMs) on cytochrome P450-dependent monooxygenases (MFOs) induction and cytochrome P4501A1 (CYP1A1) gene expression
were estimated in Hep G2 cells cultured in a serum-free medium. The cells were cultured on collagen type I- and II-, fibronectin-,
and matrigel-coated dishes and MFO activities were induced by the addition of 3-methylcholanthrene (MC). The induction of
ethoxycoumarin O-deethylase (ECOD) and alkoxyresorufin O-dealkylase activities as well as the expression of CYP1A1 mRNA were
also determined. ECOD and methoxy- and ethoxyresorufin O-dealkylase activities in Hep G2 cells were enhanced by culturing
the cells using a serum-free medium on fibronectin- or matrigel-coated dishes. ECOD activity on fibronectin-coated dishes
was about 3-fold higher than that using a serum-supplemented medium on untreated dishes. Furthermore, both immobilized and
soluble fibronectin enhanced the induction of MFOs. The expression of CYP1A1 mRNA using fibronectin-coated dishes was about
2-fold higher than that using a serum-supplemented medium on untreated dishes. These findings suggest that the gene expression
in cultured cells is greatly influenced by ECMs. By using fibronectin-coated dishes to cell culture in a serum-free medium,
reproducible and highly sensitive results can be obtained in experiments using cultured cells.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
19.
Evidence for cytochrome P-450 and P-450-mediated benzo(a) pyrene hydroxylation in the white rot fungus Phanerochaete chrysosporium 总被引:2,自引:0,他引:2
Segula Masaphy Dan Levanon Yigal Henis K. Venkateswarlu Steven L. Kelly 《FEMS microbiology letters》1996,135(1):51-55
Abstract The presence of cytochrome P-450 and P-450-mediated benzo(a)pyrene hydroxylase activity in both microsomal and soluble fractions of the white rot fungus Phanerochaete chrysosporium was shown. The reduced carbon monoxide difference spectrum showed maxima at 448–450 and 452–454 nm for microsomal and cytosolic fractions, respectively. Both P-450 fractions produced a Type I substrate binding spectrum on addition of benzo(a)pyrene. Activity for benzo(a)pyrene hydroxylation was NADPH-dependent and inhibited by carbon monoxide. K m values for activity showed a difference between the cellular fractions with a K m of 89 μM for microsomal P-450 and 400 μM for cytosolic P-450. The V max values observed were 0.83 nmol min− (nmol microsomal P-450) −1 and 0.4 nmol min−1 (nmol cytosolic P-450)−1 . The results indicate that P-450-mediated benzo(a)pyrene hydroxylase activity could play a role in xenobiotic transformation by this fungus beside the known ligninolytic exocellular enzymes. 相似文献