Identification of Novel Substrates for Human Cytochrome P450 2J2
Several antihistamine drugs including terfenadine, ebastine, and astemizole have been identified as substrates for CYP2J2. The overall importance of this enzyme in drug metabolism has not been fully explored. In this study, 139 marketed therapeutic agents and compounds were screened as potential CYP2J2 substrates. Eight novel substrates were identified that vary in size and overall topology from relatively rigid structures (amiodarone) to larger complex structures (cyclosporine). The substrates displayed in vitro intrinsic clearance values ranging from 0.06 to 3.98 mul/min/pmol CYP2J2. Substrates identified for CYP2J2 are also metabolized by CYP3A4. Extracted ion chromatograms of metabolites observed for albendazole, amiodarone, astemizole, thioridazine, mesoridazine, and danazol showed marked differences in the regioselectivity of CYP2J2 and CYP3A4. CYP3A4 commonly metabolized compounds at multiple sites, whereas CYP2J2 metabolism was more restrictive and limited, in general, to a single site for large compounds. Although the CYP2J2 active site can accommodate large substrates, it may be more narrow than CYP3A4, limiting metabolism to moieties that can extend closer toward the active heme iron. For albendazole, CYP2J2 forms a unique metabolite compared with CYP3A4. Albendazole and amiodarone were evaluated in various in vitro systems including recombinant CYP2J2 and CYP3A4, pooled human liver microsomes (HLM), and human intestinal microsomes (HIM). The Michaelis-Menten-derived intrinsic clearance of N-desethyl amiodarone was 4.6 greater in HLM than in HIM and 17-fold greater in recombinant CYP3A4 than in recombinant CYP2J2. The resulting data suggest that CYP2J2 may be an unrecognized participant in first-pass metabolism, but its contribution is minor relative to that of CYP3A4.
Available from: Aditi Das
- "Therefore these were two obvious substrates to study (McDougle et al. 2014; McDougle et al. 2013). CYP2J2 is also known to metabolize several drugs and the predominant drug were chosen for this study (terfenadine, TFN; ebastine, EBA; MSPPOH; danazol, DAN; and doxorubicin, DOX) (Hashizume et al. 2002; Lafite et al. 2007; Lee et al. 2010; McDougle et al. 2014; Zhang et al. 2009). "
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ABSTRACT: Cytochrome P450s are the primary enzymes involved in phase I drug metabolism. They are an
important target for early drug discovery research. However, high-throughput drug screening of
P450s is limited by poor protein stability and lack of consistent measurement of binding events.
Here we present the detection of substrate binding to cytochrome P450-2J2 (CYP2J2), the
predominant P450 in the human heart, using a combination of Nanodisc technology and a
nanohole plasmonic sensor called nanoplasmonic Lycurgus cup array (nanoLCA). The Nanodisc,
a nanoscale membrane bilayer disc, is used to stabilize the protein on the metallic plasmonic
surface. Absorption spectroscopy of seven different substrates binding to CYP2J2 in solution
showed that they are all type I, resulting in shifting of the protein bands to lower wavelengths
(blue shift). Detection on the nanoLCA sensor also showed spectral blue shifts of CYP2J2
following substrate binding. Finite Difference Time Domain (FDTD) electromagnetic simulation
suggested that the blue shift on the nanoLCA is because of the hybridization of plasmon
polariton Bloch wave and the electronic resonance of the heme group of CYP2J2. We found the
plasmonic properties of the nanoLCA sensor to be highly reproducible, which allowed
comparisons among the different substrates at different concentrations. Further, due to the unique
spectral properties of the nanoLCA sensor, including the transmission of a single color, we were
able to perform colorimetric detection of the binding events. These results indicate that a
resonance plasmonic sensing mechanism can be used to distinguish between different substrates
of the same binding type at different concentrations binding to P450s and that the nanoLCA
sensor has the potential to provide consistent high-throughput measurements of this system
Biosensors & Bioelectronics 07/2015; · 6.41 Impact Factor
Available from: Songhee Han
- "Recently, the drug metabolism by human P450 2J2 was determined and its clinical relevance was reported. Several antihistamine drugs including terfenadine, ebastine, and astemizole have been identified as substrates for P450 2J2 (10,11). "
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ABSTRACT: The human cytochrome P450 2J2 catalyzes an epoxygenase reaction to oxidize various fatty acids including arachidonic acid. In this study, three recombinant enzyme constructs of P450 2J2 were heterologously expressed in Escherichia coli and their P450 proteins were successfully purified using a Ni(2+)-NTA affinity column. Deletion of 34 amino acid residues in N-terminus of P450 2J2 enzyme (2J2-D) produced the soluble enzyme located in the cytosolic fraction. The enzymatic analysis of this truncated protein indicated the typical spectral characteristics and functional properties of P450 2J2 enzyme. P450 2J2-D enzymes from soluble fraction catalyzed the oxidation reaction of terfenadine to the hydroxylated product. However, P450 2J2-D enzymes from membrane fraction did not support the P450 oxidation reaction although it displayed the characteristic CO-binding spectrum of P450. Our finding of these features in the N-terminal modified P450 2J2 enzyme could help understand the biological functions and the metabolic roles of P450 2J2 enzyme and make the crystallographic analysis of the P450 2J2 structure feasible for future studies.
Toxicological Research 03/2014; 30(1):33-8. DOI:10.5487/TR.2014.30.1.033
Available from: Rüdiger Kaspera
- "Most substrates identified for CYP2J2 are also metabolized by CYP3A4 and other isozymes (Lee et al., 2010); therefore, a specific reaction catalyzed by CYP2J2 is necessary to determine the contribution of CYP2J2 to overall P450-mediated drug metabolism. In our previous work, we identified amiodarone side chain hydroxylation as a CYP2J2-specific metabolic pathway based on P450 reaction phenotyping , which indicated that no other P450 appreciably contributed to the formation of this metabolite (Lee et al., 2010). A specific substrate/inhibitor pair for CYP2J2 may reveal a role for CYP2J2 in drug metabolism that may be underestimated, especially in extrahepatic tissues. "
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ABSTRACT: CYP2J2, an arachidonic acid epoxygenase, is recognized for its role in the first-pass metabolism of astemizole and ebastine. To fully assess the role of CYP2J2 in drug metabolism, a selective substrate and potent specific chemical inhibitor are essential. In this study, we report amiodarone 4-hydoxylation as a specific CYP2J2-catalyzed reaction with no CYP3A4, or other drug-metabolizing enzyme, involvement. Amiodarone 4-hydroxylation enabled the determination of liver relative activity factor and intersystem extrapolation factor for CYP2J2. Amiodarone 4-hydroxylation correlated with astemizole O-demethylation but not with CYP2J2 protein content in a sample of human liver microsomes. To identify a specific CYP2J2 inhibitor, 138 drugs were screened using terfenadine and astemizole as probe substrates with recombinant CYP2J2. Forty-two drugs inhibited CYP2J2 activity by ≥50% at 30 μM, but inhibition was substrate-dependent. Of these, danazol was a potent inhibitor of both hydroxylation of terfenadine (IC(50) = 77 nM) and O-demethylation of astemizole (K(i) = 20 nM), and inhibition was mostly competitive. Danazol inhibited CYP2C9, CYP2C8, and CYP2D6 with IC(50) values of 1.44, 1.95, and 2.74 μM, respectively. Amiodarone or astemizole were included in a seven-probe cocktail for cytochrome P450 (P450) drug-interaction screening potential, and astemizole demonstrated a better profile because it did not appreciably interact with other P450 probes. Thus, danazol, amiodarone, and astemizole will facilitate the ability to determine the metabolic role of CYP2J2 in hepatic and extrahepatic tissues.
Drug metabolism and disposition: the biological fate of chemicals 02/2012; 40(5):943-51. DOI:10.1124/dmd.111.043505 · 3.25 Impact Factor
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