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Riffle M, Hoopmann MR, Jaschob D, Zhong G, Moritz RL, MacCoss MJ, Davis TN, Isoherranen N, Zelter A. Discovery and Visualization of Uncharacterized Drug-Protein Adducts Using Mass Spectrometry. Anal Chem 2022; 94:3501-3509. [PMID: 35184559 PMCID: PMC8892443 DOI: 10.1021/acs.analchem.1c04101] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
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Drugs are often metabolized
to reactive intermediates that form
protein adducts. Adducts can inhibit protein activity, elicit immune
responses, and cause life-threatening adverse drug reactions. The
masses of reactive metabolites are frequently unknown, rendering traditional
mass spectrometry-based proteomics approaches incapable of adduct
identification. Here, we present Magnum, an open-mass search algorithm
optimized for adduct identification, and Limelight, a web-based data
processing package for analysis and visualization of data from all
existing algorithms. Limelight incorporates tools for sample comparisons
and xenobiotic-adduct discovery. We validate our tools with three
drug/protein combinations and apply our label-free workflow to identify
novel xenobiotic-protein adducts in CYP3A4. Our new methods and software
enable accurate identification of xenobiotic-protein adducts with
no prior knowledge of adduct masses or protein targets. Magnum outperforms
existing label-free tools in xenobiotic-protein adduct discovery,
while Limelight fulfills a major need in the rapidly developing field
of open-mass searching, which until now lacked comprehensive data
visualization tools.
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Affiliation(s)
- Michael Riffle
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, United States
| | | | - Daniel Jaschob
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, United States
| | - Guo Zhong
- Department of Pharmaceutics, University of Washington, Seattle, Washington 98195, United States
| | - Robert L Moritz
- Institute for Systems Biology, Seattle, Washington 98109, United States
| | - Michael J MacCoss
- Department of Genome Sciences, University of Washington, Seattle, Washington 98195, United States
| | - Trisha N Davis
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, United States
| | - Nina Isoherranen
- Department of Pharmaceutics, University of Washington, Seattle, Washington 98195, United States
| | - Alex Zelter
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, United States
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2
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Nellikka RK, Sreeja JS, Dharmapal D, John R, Monteiro A, Macedo JC, Conde C, Logarinho E, Sunkel CE, Sengupta S. α-Fodrin is required for the organization of functional microtubules during mitosis. Cell Cycle 2019; 18:2713-2726. [PMID: 31455186 DOI: 10.1080/15384101.2019.1656476] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The cytoskeleton protein α-fodrin plays a major role in maintaining structural stability of membranes. It was also identified as part of the brain γ-tubulin ring complex, the major microtubule nucleator. Here, we investigated the requirement of α-fodrin for microtubule spindle assembly during mitotic progression. We found that α-fodrin depletion results in abnormal mitosis with uncongressed chromosomes, leading to prolonged activation of the spindle assembly checkpoint and a severe mitotic delay. Further, α-fodrin repression led to the formation of shortened spindles with unstable kinetochore-microtubule attachments. We also found that the mitotic kinesin CENP-E had reduced levels at kinetochores to likely account for the chromosome misalignment defects in α-fodrin-depleted cells. Importantly, we showed these cells to exhibit reduced levels of detyrosinated α-tubulin, which primarily drives CENP-E localization. Since proper microtubule dynamics and chromosome alignment are required for completion of normal mitosis, this study reveals an unforeseen role of α-fodrin in regulating mitotic progression. Future studies on these lines of observations should reveal important mechanistic insight for fodrin's involvement in cancer.
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Affiliation(s)
- Rohith Kumar Nellikka
- Cancer Research Program-III, Rajiv Gandhi Centre for Biotechnology, University of Kerala , Thiruvananthapuram , India
| | - Jamuna S Sreeja
- Cancer Research Program-III, Rajiv Gandhi Centre for Biotechnology, University of Kerala , Thiruvananthapuram , India
| | - Dhrishya Dharmapal
- Cancer Research Program-III, Rajiv Gandhi Centre for Biotechnology, University of Kerala , Thiruvananthapuram , India
| | - Rince John
- Cancer Research Program-III, Rajiv Gandhi Centre for Biotechnology, University of Kerala , Thiruvananthapuram , India
| | | | | | - Carlos Conde
- i3S-IBMC, Universidade do Porto , Porto , Portugal
| | | | - Claudio E Sunkel
- i3S-IBMC, Universidade do Porto , Porto , Portugal.,ICBAS-Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto , Porto , Portugal
| | - Suparna Sengupta
- Cancer Research Program-III, Rajiv Gandhi Centre for Biotechnology, University of Kerala , Thiruvananthapuram , India
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3
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Sathianathen NJ, Krishna S, Anderson JK, Weight CJ, Gupta S, Konety BR, Griffith TS. The current status of immunobased therapies for metastatic renal-cell carcinoma. Immunotargets Ther 2017; 6:83-93. [PMID: 29255699 PMCID: PMC5723125 DOI: 10.2147/itt.s134850] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The management of metastatic renal-cell carcinoma (mRCC) represents an important clinical challenge. Since being approved in the early 1990s, aspecific immunotherapy has been a mainstay of treatment for mRCC and the only therapy that has demonstrated long-term cures for mRCC. However, in recent times there have been landmark advances made in the field of specific immunotherapy for a number of malignancies, including kidney cancer. This review outlines the range of immunobased agents currently available for the treatment of mRCC.
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Affiliation(s)
| | | | | | | | - Shilpa Gupta
- Masonic Cancer Center
- Division of Hematology, Oncology, and Transplantation
| | | | - Thomas S Griffith
- Department of Urology
- Masonic Cancer Center
- Center for Immunology
- Microbiology, Immunology, and Cancer Biology Graduate Program, University of Minnesota, Minneapolis, MN, USA
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4
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Lampe JN. Advances in the Understanding of Protein-Protein Interactions in Drug Metabolizing Enzymes through the Use of Biophysical Techniques. Front Pharmacol 2017; 8:521. [PMID: 28848438 PMCID: PMC5550701 DOI: 10.3389/fphar.2017.00521] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Accepted: 07/24/2017] [Indexed: 02/01/2023] Open
Abstract
In recent years, a growing appreciation has developed for the importance of protein-protein interactions to modulate the function of drug metabolizing enzymes. Accompanied with this appreciation, new methods and technologies have been designed for analyzing protein-protein interactions both in vitro and in vivo. These technologies have been applied to several classes of drug metabolizing enzymes, including: cytochrome P450's (CYPs), monoamine oxidases (MAOs), UDP-glucuronosyltransferases (UGTs), glutathione S-transferases (GSTs), and sulfotransferases (SULTs). In this review, we offer a brief description and assessment of the impact of many of these technologies to the study of protein-protein interactions in drug disposition. The still expanding list of these techniques and assays has the potential to revolutionize our understanding of how these enzymes carry out their important functions in vivo.
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Affiliation(s)
- Jed N Lampe
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical CenterKansas City, MO, United States
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5
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Ducharme J, Auclair K. Use of bioconjugation with cytochrome P450 enzymes. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017. [PMID: 28625736 DOI: 10.1016/j.bbapap.2017.06.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Bioconjugation, defined as chemical modification of biomolecules, is widely employed in biological and biophysical studies. It can expand functional diversity and enable applications ranging from biocatalysis, biosensing and even therapy. This review summarizes how chemical modifications of cytochrome P450 enzymes (P450s or CYPs) have contributed to improving our understanding of these enzymes. Genetic modifications of P450s have also proven very useful but are not covered in this review. Bioconjugation has served to gain structural information and investigate the mechanism of P450s via photoaffinity labeling, mechanism-based inhibition (MBI) and fluorescence studies. P450 surface acetylation and protein cross-linking have contributed to the investigation of protein complexes formation involving P450 and its redox partner or other P450 enzymes. Finally, covalent immobilization on polymer surfaces or electrodes has benefited the areas of biocatalysis and biosensor design. This article is part of a Special Issue entitled: Cytochrome P450 biodiversity and biotechnology, edited by Erika Plettner, Gianfranco Gilardi, Luet Wong, Vlada Urlacher, Jared Goldstone.
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Affiliation(s)
- Julie Ducharme
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Karine Auclair
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada.
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6
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Sevrioukova IF. High-Level Production and Properties of the Cysteine-Depleted Cytochrome P450 3A4. Biochemistry 2017; 56:3058-3067. [PMID: 28590129 DOI: 10.1021/acs.biochem.7b00334] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Human drug-metabolizing cytochrome P450 3A4 (CYP3A4) is a dynamic enzyme with a large and highly malleable active site that can fit structurally diverse compounds. Despite extensive investigations, structure-function relationships and conformational dynamics in CYP3A4 are not fully understood. This study was undertaken to engineer a well-expressed and functionally active cysteine-depleted CYP3A4 that can be used in biochemical and biophysical studies. cDNA codon optimization and screening mutagenesis were utilized to boost the level of bacterial expression of CYP3A4 and identify the least harmful substitutions for all six non-heme-ligating cysteines. The C58A/C64M/C98A/C239T/C377A/C468S (Cys-less) mutant was found to be expressed as highly as the optimized wild-type (opt-WT) CYP3A4. The high-resolution X-ray structures of opt-WT and Cys-less CYP3A4 revealed that gene optimization leads to a different folding in the Phe108 and Phe189 regions and promotes binding of the active site glycerol that interlocks Ser119 and Arg212, critical for ligand association, and the hydrophobic cluster adjacent to Phe108. Crowding and decreased flexibility of the active site, as well as structural alterations observed at the C64M, C239T, and C468S mutational sites, might be responsible for the distinct ligand binding behavior of opt-WT and Cys-less CYP3A4. Nonetheless, the Cys-less mutant could be used for structure-function investigations because it orients bromoergocryptine and ritonavir (a high-affinity substrate and a high-potency inhibitor, respectively) like the WT and has a higher activity toward 7-benzyloxy(4-trifluoromethyl)coumarin.
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Affiliation(s)
- Irina F Sevrioukova
- Department of Molecular Biology and Biochemistry, University of California , Irvine, California 92697-3900, United States
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7
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Chung HS, Lee S, Park SJ. Oxidation Protection in Metal-Binding Peptide Motif and Its Application to Antibody for Site-Selective Conjugation. PLoS One 2016; 11:e0159451. [PMID: 27420328 PMCID: PMC4946781 DOI: 10.1371/journal.pone.0159451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 07/01/2016] [Indexed: 11/18/2022] Open
Abstract
Here, we demonstrate that a metal ion binding motif could serve as an efficient and robust tool for site-specific conjugation strategy. Cysteine-containing metal binding motifs were constructed as single repeat or tandem repeat peptides and their metal binding characteristics were investigated. The tandem repeats of the Cysteine-Glycine-Histidine (CGH) metal ion binding motif exhibited concerted binding to Co(II) ions, suggesting that conformational transition of peptide was triggered by the sequential metal ion binding. Evaluation of the free thiol content after reduction by reducing reagent showed that metal-ion binding elicited strong retardation of cysteine oxidation in the order of Zn(II)>Ni(II)>Co(II). The CGH metal ion binding motif was then introduced to the C-terminus of antibody heavy chain and the metal ion-dependent characteristics of oxidation kinetics were investigated. As in the case of peptides, CGH-motif-introduced antibody exhibited strong dependence on metal ion binding to protect against oxidation. Zn(II)-saturated antibody with tandem repeat of CGH motif retains the cysteine reactivity as long as 22 hour even with saturating O2 condition. Metal-ion dependent fluorophore labeling clearly indicated that metal binding motifs could be employed as an efficient tool for site-specific conjugation. Whereas Trastuzumab without a metal ion binding site exhibited site-nonspecific dye conjugation, Zn(II) ion binding to antibody with a tandem repeat of CGH motif showed that fluorophores were site-specifically conjugated to the heavy chain of antibody. We believe that this strong metal ion dependence on oxidation protection and the resulting site-selective conjugation could be exploited further to develop a highly site-specific conjugation strategy for proteins that contain multiple intrinsic cysteine residues, including monoclonal antibodies.
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Affiliation(s)
- Hye-Shin Chung
- Department of Biological Sciences and Biotechnology, College of Life Science and Nano Technology, Hannam University, 1646, Yuseong-daero, Yuseong-gu, Daejeon, Korea
- Alteogen Inc., Yuseong-daero 62, Jeon-min Dong, Yuseong-gu, Daejeon, Korea
| | - Sunbae Lee
- Alteogen Inc., Yuseong-daero 62, Jeon-min Dong, Yuseong-gu, Daejeon, Korea
| | - Soon Jae Park
- Alteogen Inc., Yuseong-daero 62, Jeon-min Dong, Yuseong-gu, Daejeon, Korea
- * E-mail:
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8
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Gricman Ł, Weissenborn MJ, Hoffmann SM, Borlinghaus N, Hauer B, Pleiss J. Redox Partner Interaction Sites in Cytochrome P450 Monooxygenases:In SilicoAnalysis and Experimental Validation. ChemistrySelect 2016. [DOI: 10.1002/slct.201600369] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Łukasz Gricman
- Institute of Technical Biochemistry; University of Stuttgart; Allmandring 31 70569 Stuttgart Germany
| | - Martin J. Weissenborn
- Institute of Technical Biochemistry; University of Stuttgart; Allmandring 31 70569 Stuttgart Germany
| | - Sara M. Hoffmann
- Institute of Technical Biochemistry; University of Stuttgart; Allmandring 31 70569 Stuttgart Germany
| | - Niels Borlinghaus
- Institute of Technical Biochemistry; University of Stuttgart; Allmandring 31 70569 Stuttgart Germany
| | - Bernhard Hauer
- Institute of Technical Biochemistry; University of Stuttgart; Allmandring 31 70569 Stuttgart Germany
| | - Jürgen Pleiss
- Institute of Technical Biochemistry; University of Stuttgart; Allmandring 31 70569 Stuttgart Germany
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9
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Hlavica P. Mechanistic basis of electron transfer to cytochromes p450 by natural redox partners and artificial donor constructs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 851:247-97. [PMID: 26002739 DOI: 10.1007/978-3-319-16009-2_10] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Cytochromes P450 (P450s) are hemoproteins catalyzing oxidative biotransformation of a vast array of natural and xenobiotic compounds. Reducing equivalents required for dioxygen cleavage and substrate hydroxylation originate from different redox partners including diflavin reductases, flavodoxins, ferredoxins and phthalate dioxygenase reductase (PDR)-type proteins. Accordingly, circumstantial analysis of structural and physicochemical features governing donor-acceptor recognition and electron transfer poses an intriguing challenge. Thus, conformational flexibility reflected by togging between closed and open states of solvent exposed patches on the redox components was shown to be instrumental to steered electron transmission. Here, the membrane-interactive tails of the P450 enzymes and donor proteins were recognized to be crucial to proper orientation toward each other of surface sites on the redox modules steering functional coupling. Also, mobile electron shuttling may come into play. While charge-pairing mechanisms are of primary importance in attraction and complexation of the redox partners, hydrophobic and van der Waals cohesion forces play a minor role in docking events. Due to catalytic plasticity of P450 enzymes, there is considerable promise in biotechnological applications. Here, deeper insight into the mechanistic basis of the redox machinery will permit optimization of redox processes via directed evolution and DNA shuffling. Thus, creation of hybrid systems by fusion of the modified heme domain of P450s with proteinaceous electron carriers helps obviate the tedious reconstitution procedure and induces novel activities. Also, P450-based amperometric biosensors may open new vistas in pharmaceutical and clinical implementation and environmental monitoring.
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Affiliation(s)
- Peter Hlavica
- Walther-Straub-Institut für Pharmakologie und Toxikologie der LMU, Goethestrasse 33, 80336, München, Germany,
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10
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Zhao C, Gao Q, Roberts AG, Shaffer SA, Doneanu CE, Xue S, Goodlett DR, Nelson SD, Atkins WM. Cross-linking mass spectrometry and mutagenesis confirm the functional importance of surface interactions between CYP3A4 and holo/apo cytochrome b(5). Biochemistry 2012; 51:9488-500. [PMID: 23150942 DOI: 10.1021/bi301069r] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cytochrome b(5) (cyt b(5)) is one of the key components in the microsomal cytochrome P450 monooxygenase system. Consensus has not been reached about the underlying mechanism of cyt b(5) modulation of CYP catalysis. Both cyt b(5) and apo b(5) are reported to stimulate the activity of several P450 isoforms. In this study, the surface interactions of both holo and apo b(5) with CYP3A4 were investigated and compared for the first time. Chemical cross-linking coupled with mass spectrometric analysis was used to identify the potential electrostatic interactions between the protein surfaces. Subsequently, the models of interaction of holo/apo b(5) with CYP3A4 were built using the identified interacting sites as constraints. Both cyt b(5) and apo b(5) were predicted to bind to the same groove on CYP3A4 with close contacts to the B-B' loop of CYP3A4, a substrate recognition site. Mutagenesis studies further confirmed that the interacting sites on CYP3A4 (Lys96, Lys127, and Lys421) are functionally important. Mutation of these residues reduced or abolished cyt b(5) binding affinity. The critical role of Arg446 on CYP3A4 in binding to cyt b(5) and/or cytochrome P450 reductase was also discovered. The results indicated that electrostatic interactions on the interface of the two proteins are functionally important. The results indicate that apo b(5) can dock with CYP3A4 in a manner analogous to that of holo b(5), so electron transfer from cyt b(5) is not required for its effects.
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Affiliation(s)
- Chunsheng Zhao
- Department of Medicinal Chemistry, University of Washington, Box 357610, Seattle, WA 98195, USA
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11
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Lin HL, Kenaan C, Zhang H, Hollenberg PF. Reaction of human cytochrome P450 3A4 with peroxynitrite: nitrotyrosine formation on the proximal side impairs its interaction with NADPH-cytochrome P450 reductase. Chem Res Toxicol 2012; 25:2642-53. [PMID: 23016756 DOI: 10.1021/tx3002753] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The reaction of peroxynitrite (PN) with purified human cytochrome P450 3A4 (CYP3A4) resulted in the loss of the reduced-CO difference spectrum, but the absolute absorption spectrum of the heme was not significantly altered. The loss of 7-benzyloxy-4-(trifluoromethyl)coumarin (BFC) O-debenzylation activity of CYP3A4 was concentration-dependent with respect to PN, and the loss of BFC activity supported by NADPH-cytochrome P450 reductase (CPR) was much greater than that supported by tert-butyl hydroperoxide. Moreover, the PN-treated CYP3A4 exhibited a reduced-CO spectrum when reduced by CPR that was much smaller than when it was reduced by dithionite. These results suggest that modification of CYP3A4 by PN may impair its interaction with CPR, leading to the loss of catalytic activity. Tyrosine nitration, as measured by an increase in mass of 45 Da due to the addition of a nitro group, was used as a biomarker for protein modification by PN. PN-treated CYP3A4 was digested by trypsin and endoproteinase Glu C, and nitrotyrosine formation was then determined by using electrospray ionization-liquid chromatography-tandem mass spectrometry. Tyr residues 99, 307, 347, 430, and 432 were found to be nitrated. Using the GRAMM-X docking program, the structure for the CYP3A4-CPR complex shows that Tyr99, Tyr347, and Tyr430 are on the proximal side of CYP3A4 and are in close contact with three acidic residues in the FMN domain of CPR, suggesting that modification of one or more of these tyrosine residues by PN may influence CPR binding or the transfer of electrons to CYP3A4. Mutagenesis of Tyr430 to Phe or Val revealed that both the aromatic and the hydroxyl groups of Tyr are required for CPR-dependent catalytic activity and thus support the idea that the proximal side Tyr participates in the 3A4-CPR interaction. In conclusion, modification of tyrosine residues by PN and their subsequent identification can be used to enhance our knowledge of the structure/function relationships of the P450s with respect to the electron transfer steps, which are critical for P450 activity.
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Affiliation(s)
- Hsia-lien Lin
- Department of Pharmacology, University of Michigan, 2301 MSRB III, 1150 West Medical Center Drive, Ann Arbor, Michigan 48109-5632, United States
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12
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Ménard A, Huang Y, Karam P, Cosa G, Auclair K. Site-specific fluorescent labeling and oriented immobilization of a triple mutant of CYP3A4 via C64. Bioconjug Chem 2012; 23:826-36. [PMID: 22433037 DOI: 10.1021/bc200672s] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The generation of site-specific bioconjugates of proteins is highly desired for a number of biophysical and nanotechnological applications. To this end, many strategies have been developed that allow the specific modification of certain canonical amino acids and, more recently, noncanonical functional groups. P450 enzymes are heme-dependent monooxygenases involved in xenobiotic metabolism and in the biosynthesis of a variety of secondary metabolites. We became interested in the site-specific modification of these enzymes, CYP3A4 in particular, through our studies of their in vitro biocatalytic properties and our desire to exploit their remarkable ability to oxidize unactivated C-H bonds in a regio- and stereospecific manner. Obtained via a partial cysteine-depletion approach, a functional triple mutant of CYP3A4 (C98S/C239S/C468G) is reported here which is singly modified at C64 by maleimide-containing groups. While cysteine-labeling of the wild-type enzyme abolished >90% of its enzymatic activity, this mutant retained ≥75% of the activity of the unmodified wild-type enzyme with 9 of the 18 maleimides that were tested. These included both fluorescent and solid-supported maleimides. The loss of activity observed after labeling with some maleimides is attributed to direct enzyme inhibition rather than to steric effects. We also demonstrate the functional immobilization of this mutant on maleimide-functionalized agarose resin and silica microspheres.
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Affiliation(s)
- Amélie Ménard
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada, H3A 0B8
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13
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Rawal S, Yip SSM, Coulombe RA. Cloning, Expression and Functional Characterization of Cytochrome P450 3A37 from Turkey Liver with High Aflatoxin B1 Epoxidation Activity. Chem Res Toxicol 2010; 23:1322-9. [DOI: 10.1021/tx1000267] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sumit Rawal
- Department of Veterinary Sciences, Graduate Program in Toxicology, Utah State University, Logan, Utah 84322-4620
| | - Shirley S. M. Yip
- Department of Veterinary Sciences, Graduate Program in Toxicology, Utah State University, Logan, Utah 84322-4620
| | - Roger A. Coulombe
- Department of Veterinary Sciences, Graduate Program in Toxicology, Utah State University, Logan, Utah 84322-4620
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14
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Choi KY, Kim TJ, Koh SK, Roh CH, Pandey BP, Lee N, Kim BG. A-ringortho-specific monohydroxylation of daidzein by cytochrome P450s ofNocardia farcinicaIFM10152. Biotechnol J 2009; 4:1586-95. [DOI: 10.1002/biot.200900157] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Harrelson JP, Atkins WM, Nelson SD. Multiple-ligand binding in CYP2A6: probing mechanisms of cytochrome P450 cooperativity by assessing substrate dynamics. Biochemistry 2008; 47:2978-88. [PMID: 18247580 DOI: 10.1021/bi702020y] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The contribution of ligand dynamics to CYP allosterism has not been considered in detail. On the basis of a previous study, we hypothesized that CYP2A6 and CYP2E1 accommodate multiple xylene ligands. As a result, the intramolecular ( k H/ k D) obs values observed for some xylene isomers are expected to be dependent on ligand concentration with contributions from [CYP.xylene] and [CYP.xylene.xylene], etc. To explore this possibility and the utility of kinetic isotope effects in characterizing allosteric CYP behavior, steady state kinetics, product ratios, and ( k H/ k D) obs values for CYP2E1 and CYP2A6 oxidation of m-xylene-alpha- (2)H 3 and p-xylene-alpha- (2)H 3 were determined. Evidence is presented that CYP2A6 accommodates multiple ligands and that intramolecular isotope effect experiments can provide insight into the mechanisms of multiple-ligand binding. CYP2A6 exhibited cooperative kinetics for m-xylene-alpha- (2)H 3 oxidation and a concentration-dependent decrease in the m-methylbenzylalcohol:2,4-dimethylphenol product ratio (9.8 +/- 0.1 and 4.8 +/- 0.3 at 2.5 microM and 1 mM, respectively). Heterotropic effects were observed as well, as incubations containing both 15 microM m-xylene-alpha- (2)H 3 and 200 microM p-xylene resulted in further reduction of the product ratio (2.4 +/- 0.2). When p-xylene (60 microM) was replaced with deuterium-labeled d 6- p-xylene (60 microM), an intermolecular competitive inverse isotope effect on 2,4-dimethylphenol formation [( k H/ k D) obs = 0.49] was observed, indicating that p-xylene exerts heterotropic effects by residing in the active site simultaneously with m-xylene. The data indicate that there is a concentration-dependent decrease in the reorientation rate of m-xylene, as no increase in ( k H/ k D) obs was observed in the presence of an increased level of metabolic switching. That is, the accommodation of a second xylene molecule in the active site leads to a decrease in substrate dynamics.
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Affiliation(s)
- John P Harrelson
- School of Pharmacy, Pacific University, HPC-Ste 451, Hillsboro, Oregon 97123, USA.
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