Inhibition of CYP2B4 by the mechanism-based inhibitor 2-ethynylnaphthalene: Inhibitory potential of 2EN is dependent on the size of the substrate

Cheng, Dongmei; Reed, James R.; Harris, Danni L.; Backes, Wayne L.

doi:10.1016/j.abb.2007.03.023

Cited by 5 publications

(11 citation statements)

References 26 publications

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“…The conclusions as to whether 2EN and the substrates could co-bind to a common cavity were not dependent on order of docking of 2EN and the substrate. The results are relevant to our prior finding that the reversible inhibition by 2EN of substrate metabolism was highly correlated with substrate size and architecture (14).…”

Section: Hierarchical Dockingsupporting

confidence: 68%

“…As mentioned in our previous report (14), 2EN can serve as both a reversible and an irreversible inhibitor of CYP2B4-mediated metabolism. Although the irreversible inactivation is similar to that expected for typical mechanism-based inhibitors, the reversible component was unusual.…”

Section: Examination Of the Reversible Inhibition Of Cyp2b4-dependentmentioning

confidence: 57%

“…Product formation for each of the substrates was measured as described previously (14), using standard fluorescence assays for 7EC, 7EFC, 7PR, 7BR, and BZP assays (22)(23)(24)(25)(26)(27). PNA metabolism was determined by monitoring the absorbance at 405 nm resulting from the formation of p-nitrophenol (28).…”

Section: Determination Of the Type Of Reversible Inhibition Of Cyp2b4mentioning

confidence: 99%

“…Although the irreversible inactivation is similar to that expected for typical mechanism-based inhibitors, the reversible component was unusual. The ability of 1 μM 2EN to reversibly inhibit substrate metabolism could be divided into three groups (14): (a) little to no inhibition (PNA), (b) a moderate degree of inhibition (13%-30% for 7EC, 7EFC and BZP), and (c) significant reversible inhibition (50%-71% for 7BR, 7PR, and TS). The ability of 2EN to inhibit metabolism of these substrates was not related to the affinity of the substrates for the active site, but did appear to be related to the molecular size of the substrate, particularly the length of the molecule.…”

Section: Examination Of the Reversible Inhibition Of Cyp2b4-dependentmentioning

confidence: 99%

“…Previously, our laboratory reported on the inhibition of CYP2B4 by 2EN, where both the irreversible and reversible components were characterized (14). This was accomplished by examining the residual metabolism, for seven different CYP2B4 substrates before and after inactivation with 2EN.…”

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confidence: 99%

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Inhibition of CYP2B4 by 2-ethynylnaphthalene: Evidence for the co-binding of substrate and inhibitor within the active site

Cheng¹,

Harris²,

Reed³

et al. 2007

Archives of Biochemistry and Biophysics

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Abstract2-Ethynylnaphthalene (2EN) is an effective mechanism-based inhibitor of CYP2B4. There are two inhibitory components, (1) irreversible inactivation of CYP2B4 (a typical time-dependent inactivation), and (2) a reversible component. The reversible component was unusual in that the degree of inhibition was not simply a characteristic of the enzyme-inhibitor interaction, but dependent on the size of the substrate molecule used to monitor residual activity. The effect of 2EN on the metabolism of seven CYP2B4 substrates showed that it was not an effective reversible inhibitor of substrates containing a single aromatic ring; substrates with two fused rings were competitively inhibited by 2EN; and larger substrates were non-competitively inhibited. Energy-based docking studies demonstrated that, with increasing substrate size, the energy of 2EN and substrate co-binding in the active site became unfavorable precisely at the point where 2EN became a competitive inhibitor. Hierarchical docking revealed potential allosteric inhibition sites separate from the substrate binding site.Cytochrome P450 refers to a superfamily of enzymes that catalyze the oxidation of a wide variety of exogenous and endogenous chemicals. The enzyme system most commonly supports oxygen insertion into a substrate molecule, generating a hydroxylated product; however, the initial monooxygenation can lead to a wide variety of reactions such as dealkylation, oxidative deamination, sulfoxidation, and epoxidation (1).The broad substrate selectivity of the P450 enzymes is due not only to the multiplicity of P450 enzymes, but also due to the characteristics of the active site. The active site for several of the P450 enzymes has been shown to be relatively large and capable of binding and metabolizing substrates of diverse chemical size and structure. A consequence of the large active site is its ability to accommodate multiple substrate/effector molecules. This effect is most commonly associated with CYP3A4 (2;3), where the presence of multiple compounds within the active site has been shown to alter the kinetics to exhibit cooperativity (4;5), and both substrate and product inhibition (2;6). The binding of multiple substrate/inhibitor molecules has also been documented for CYP2C9 (4), CYP ERYF (7;8), and P450 cam (9). The presence of active sites on other P450 enzymes that are sufficiently large to bind multiple ligands is clearly possible and likely, based on the relative size of the ligands as compared to the active sites of these nonspecific enzymes. 2-Ethynylnaphthalene (2EN) is a selective mechanism-based inhibitor of CYP2B4. CYP2B4 catalyzes the conversion of 2EN to the highly reactive intermediate, 2-naphthylacetic acid, which covalently modifies the apoprotein and results in its inactivation (10;11). In addition to its ability to inhibit CYP2B4-mediated reactions, 2EN could also act as a reversible inhibitor of both CYP1A1 and CYP1A2 (12). Although earlier studies reported that 2EN could act as a mechanism-based inhibitor of CYP1A proteins (...

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Section: Hierarchical Dockingsupporting

confidence: 68%

Section: Examination Of the Reversible Inhibition Of Cyp2b4-dependentmentioning

confidence: 57%

Section: Determination Of the Type Of Reversible Inhibition Of Cyp2b4mentioning

confidence: 99%

Section: Examination Of the Reversible Inhibition Of Cyp2b4-dependentmentioning

confidence: 99%

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confidence: 99%

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Inhibition of CYP2B4 by 2-ethynylnaphthalene: Evidence for the co-binding of substrate and inhibitor within the active site

Cheng¹,

Harris²,

Reed³

et al. 2007

Archives of Biochemistry and Biophysics

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Comparing the electronic properties and docking calculations of heme derivatives on CYP2B4

et al. 2008

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Cytochrome P-450 is a group of enzymes involved in the biotransformation of many substances, including drugs. These enzymes possess a heme group (1) that when it is properly modified induces several important physicochemical changes that affect their enzymatic activity. In this work, the five structurally modified heme derivatives 2-6 and the native heme 1 were docked on CYP2B4, (an isoform of P450), in order to determine whether such modifications alter their binding form and binding affinity for CYP2B4 apoprotein. In addition, docking calculations were used to evaluate the affinity of CYP2B4 apoprotein-heme complexes for aniline (A) and N-methyl-aniline (NMA). Results showing the CYP2B4 heme 4- and heme 6-apoprotein complexes to be most energetically stable indicate that either hindrance effects or electronic properties are the most important factors with respect to the binding of heme derivatives at the heme-binding site. Furthermore, although all heme-apoprotein complexes demonstrated high affinity for both A and NMA, the CYP2B4 apoprotein-5 complex had higher affinity for A, and the heme 6 complex had higher affinity for NMA. Finally, surface electronic properties (SEP) were calculated in order to explain why certain arginine residues of CYP2B4 apoprotein interact with polarizable functionalities, such as ester groups or sp ( 2 ) carbons, present in some heme derivates. The main physicochemical parameter involved in the recognition process of the heme derivatives, the CYP2B4 apoprotein and A or NMA, are reported.

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Selective Influence on Contextual Memory: Physiochemical Properties Associated with Selectivity of Benzodiazepine Ligands at GABA_AReceptors Containing the α5 Subunit

Harris

Clayton²,

Cook³

et al. 2008

J. Med. Chem.

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Ligands that bind to the benzodiazepine binding site on the GABA A receptor can attenuate or potentiate cognition. To investigate this property, the chemical determinants favoring selective binding or selective activation of the alpha5beta2gamma2 and alpha1beta2gamma2 GABA A receptor isoforms were examined. A 3D-pharmacophore, developed from a diverse set of BDZR ligands, was used as an initial basis for multivariate discriminant, fragment, and 3D-quantitative structure-activity relationship analyses, which formed the criteria for selection of additional compounds for study. We found that the electrostatic potential near the ligands' terminal substituent correlated with its binding selectivity toward the alpha5beta2gamma2 versus alpha1beta2gamma2 isoform; while the fragment length and frontier molecular orbital energetics correlated with a compounds influence on electrophysiological activity. Compounds with promising alpha5 profiles were further assessed for their ability to attenuate scopolamine-induced contextual memory impairment in mice. Surprisingly, both weak inverse agonist and antagonists that display binding selectivity toward the alpha5beta2gamma2 isoform were able to attenuate contextual memory impairment.

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Inhibition of CYP2B4 by the mechanism-based inhibitor 2-ethynylnaphthalene: Inhibitory potential of 2EN is dependent on the size of the substrate

Cited by 5 publications

References 26 publications

Inhibition of CYP2B4 by 2-ethynylnaphthalene: Evidence for the co-binding of substrate and inhibitor within the active site

Inhibition of CYP2B4 by 2-ethynylnaphthalene: Evidence for the co-binding of substrate and inhibitor within the active site

Comparing the electronic properties and docking calculations of heme derivatives on CYP2B4

Selective Influence on Contextual Memory: Physiochemical Properties Associated with Selectivity of Benzodiazepine Ligands at GABA_AReceptors Containing the α5 Subunit

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Inhibition of CYP2B4 by the mechanism-based inhibitor 2-ethynylnaphthalene: Inhibitory potential of 2EN is dependent on the size of the substrate

Cited by 5 publications

References 26 publications

Inhibition of CYP2B4 by 2-ethynylnaphthalene: Evidence for the co-binding of substrate and inhibitor within the active site

Inhibition of CYP2B4 by 2-ethynylnaphthalene: Evidence for the co-binding of substrate and inhibitor within the active site

Comparing the electronic properties and docking calculations of heme derivatives on CYP2B4

Selective Influence on Contextual Memory: Physiochemical Properties Associated with Selectivity of Benzodiazepine Ligands at GABAAReceptors Containing the α5 Subunit

Contact Info

Product

Resources

About

Selective Influence on Contextual Memory: Physiochemical Properties Associated with Selectivity of Benzodiazepine Ligands at GABA_AReceptors Containing the α5 Subunit