| 1. |
- Bolelli, K., et al.
(författare)
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Synthesis and activity mechanism of some novel 2-substituted benzothiazoles as hGSTP1-1 enzyme inhibitors
- 2017
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Ingår i: SAR and QSAR in environmental research (Print). - 1062-936X .- 1029-046X. ; 28:11, s. 927-940
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Tidskriftsartikel (refereegranskat)abstract
- Human GSTP1-1 is one of the most important proteins, which overexpresses in a large number of human tumours and is involved in the development of resistance to several anticancer drugs. So, it has become an important target in cancer treatment. In this study, 12 benzothiazole derivatives were synthesized and screened for their in vitro inhibitory activity for hGSTP1-1. Among these compounds, two of them (compounds #2 and #5) have been found to be the leads when compared with the reference drug etoposide. In order to analyse the structure-activity relationships (SARs) and to investigate the binding side interactions of the observed lead compounds, a HipHop pharmacophore model was generated and the molecular docking studies were performed by using CDocker method. In conclusion, it is observed that the lead compounds #2 and #5 possessed inhibitory activity on the hGSTP1-1 by binding to the H-site as a substrate in which the para position of the phenyl ring of the benzamide moiety on the benzothiazole ring is important. Substitution at this position with a hydrophobic group that reduces the electron density at the phenyl ring is required for the interaction with the H side active residue Tyr108.
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| 2. |
- Ertan-Bolelli, Tugba, et al.
(författare)
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Design and synthesis of 2-substituted-5-(4-trifluoromethylphenyl-sulphonamido)benzoxazole derivatives as human GST P1-1 inhibitors
- 2018
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Ingår i: Artificial Cells, Nanomedicine, and Biotechnology. - : Informa UK Limited. - 2169-1401 .- 2169-141X. ; 46:3, s. 510-517
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Tidskriftsartikel (refereegranskat)abstract
- The glutathione transferases (GSTs) are a family of widely distributed Phase II detoxification enzymes. GST P1-1 is frequently overexpressed in rat and human tumours. It is suggested that overexpression of hGST P1-1 by human tumor cells may play a role in resistance to cancer chemotherapy. Hence, hGST P1-1 can be a promising target for cancer treatment. In this study, new hGST P1-1 inhibitors, 2-(4-substitutedphenyl/benzyl)-5-(4-trifluoromethylphenylsulphonamido) benzoxazole derivatives (Va-Vk) have been designed and synthesized. Surprisingly, in vitro hGST P1-1 enzyme inhibition studies demonstrated that all of the tested compounds except Vj had better activity than the reference drug EA and it is also correlated with the docking results. Additionally we compared the interactions with hGST P1-1 enzyme of newly synthesized compound Vh (bearing CF3 group) and previously synthesized compound 5f (bearing NO2 group). According to the docking results, compound Vh bound to the hGST P1-1 enzyme with a higher affinity compared to 5f. Therefore, we can consider that these data make a sense and can explain its higher activity. The compounds that obtained from this research could be used as scaffolds in design of new potent hGST P1-1 inhibitors useful in the treatment of the resistance of cancer chemotherapy.
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| 3. |
- Hegazy, Usama M., et al.
(författare)
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Hidden Allostery in Human Glutathione Transferase P1-1 Unveiled by Unnatural Amino Acid Substitutions and Inhibition Studies
- 2013
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 425:9, s. 1509-1514
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Tidskriftsartikel (refereegranskat)abstract
- Conventional steady-state kinetic studies of the dimeric human glutathione transferase (GST) P1-1 do not reveal obvious deviations from Michaelis-Menten behavior. By contrast, engineering of the key residue Y50 of the lock-and-key motif in the subunit interface reveals allosteric properties of the enzyme. The low-activity mutant Y50C, characterized by 150-fold decreased kat and 300-fold increased K-M(GSH) values, displays an apparent Hill coefficient of 0.82 +/- 0.22. Chemical alkylation of the sulfhydryl group of Y50C by unnatural n-butyl or n-pentyl substitutions enhances the catalytic efficiency k(cat)/K-M(GSH) to near the wild-type value but still yields Hill coefficients of 0.61 +/- 0.08 and 0.86 +/- 0.1, respectively. Thus, allosteric kinetic behavior is not dependent on low activity of the enzyme. On the other hand, S-cyclobutylmethyl-substituted Y50C, which also displays high catalytic efficiency, has a Hill coefficient of 0.99 +/- 0.11, showing that subtle differences in structure at the subunit interface influence the complex kinetic behavior. Furthermore, inhibition studies of native GST P1-1 using ethacrynic acid demonstrate that a ligand bound noncovalently to the wild-type enzyme also can elicit allosteric kinetic behavior. Thus, we conclude that the GST P1-1 structure has intrinsic allostery that becomes overt under some, but not all, ambient conditions.
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| 4. |
- Lindström, Helena, et al.
(författare)
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Inhibition characteristics of equine steroid isomerase EcaGST A3-3
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Equine glutathione transferase A3-3 (EcaGST A3-3) belongs to the superfamily of detoxifying enzymes found in all organisms. However it is also the most efficient steroid double-bond isomerase known in mammals. In contrast to the rodents, Equus ferus caballus shares the steroidogenic pathway with Homo sapiens, which makes it a more suitable model for human steroidogenesis than the murine one. Inhibition of EcaGST A3-3 might help treat reproductive and neurodegenerative disorders. We screened an FDA-approved library of 1040 compounds for the ability as novel inhibitors of EcaGST A3-3. Our results revealed anthralin, sennoside A, tannic acid and ethacrynic acid as the most potent, submicromolar-range inhibitors of EcaGST A3-3 with the natural substrate Δ5-androstene-3,17-dione.
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| 5. |
- Lindström, Helena, et al.
(författare)
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Potent inhibitors of equine steroid isomerase EcaGST A3-3
- 2019
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 14:3
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Tidskriftsartikel (refereegranskat)abstract
- Equine glutathione transferase A3-3 (EcaGST A3-3) belongs to the superfamily of detoxication enzymes found in all higher organisms. However, it is also the most efficient steroid double-bond isomerase known in mammals. Equus ferus caballus shares the steroidogenic pathway with Homo sapiens, which makes the horse a suitable animal model for investigations of human steroidogenesis. Inhibition of the enzyme has potential for treatment of steroid-hormone-dependent disorders. Screening of a library of FDA-approved drugs identified 16 out of 1040 compounds, which at 10 mu M concentration afforded at least 50% inhibition of EcaGST A3-3. The most potent inhibitors, anthralin, sennoside A, tannic acid, and ethacrynic acid, were characterized by IC50 values in the submicromolar range when assayed with the natural substrate Delta(5)-androstene-3,17-dione.
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| 6. |
- Musdal, Yaman, et al.
(författare)
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Exploring sequence-function space of a poplar glutathione transferase using designed information-rich gene variants
- 2017
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Ingår i: Protein Engineering Design & Selection. - : Oxford University Press (OUP). - 1741-0126 .- 1741-0134. ; 30:8, s. 543-549
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Tidskriftsartikel (refereegranskat)abstract
- Exploring the vicinity around a locus of a protein in sequence space may identify homologs with enhanced properties, which could become valuable in biotechnical and other applications. A rational approach to this pursuit is the use of 'infologs', i.e. synthetic sequences with specific substitutions capturing maximal sequence information derived from the evolutionary history of the protein family. Ninety-five such infolog genes of poplar glutathione transferase were synthesized and expressed in Escherichia coli, and the catalytic activities of the proteins determined with alternative substrates. Sequence-activity relationships derived from the infologs were used to design a second set of 47 infologs in which 90% of the members exceeded wild-type properties. Two mutants, C2 (V55I/E95D/D108E/A160V) and G5 (F13L/C70A/G122E), were further functionally characterized. The activities of the infologs with the alternative substrates 1-chloro-2,4-dinitrobenzene and phenethyl isothiocyanate, subject to different chemistries, were positively correlated, indicating that the examined mutations were affecting the overall catalytic competence without major shift in substrate discrimination. By contrast, the enhanced protein expressivity observed in many of the mutants were not similarly correlated with the activities. In conclusion, small libraries of well-defined infologs can be used to systematically explore sequence space to optimize proteins in multidimensional functional space.
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| 7. |
- Musdal, Yaman, et al.
(författare)
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FDA-approved drugs and other compounds tested as inhibitors of human glutathione transferase P1-1
- 2013
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Ingår i: Chemico-Biological Interactions. - : Elsevier BV. - 0009-2797 .- 1872-7786. ; 205:1, s. 53-62
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Glutathione transferase P1-1 (GST P1-1) is often overexpressed in tumor cells and is regarded as a contributor to their drug resistance. Inhibitors of GST P1-1 are expected to counteract drug resistance and may therefore serve as adjuvants in the chemotherapy of cancer by increasing the efficacy of cytostatic drugs. Finding useful inhibitors among compounds used for other indications would be a shortcut to clinical applications and a search for GST P1-1 inhibitors among approved drugs and other compounds was therefore conducted. Methods: We tested 1040 FDA-approved compounds as inhibitors of the catalytic activity of purified human GST P1-1 in vitro. Results: We identified chlorophyllide, merbromine, hexachlorophene, and ethacrynic acid as the most effective GST P1-1 inhibitors with IC50 values in the low micromolar range. For comparison, these compounds were even more potent in the inhibition of human GST A3-3, an enzyme implicated in steroid hormone biosynthesis. In distinction from the other inhibitors, which showed conventional inhibition patterns, the competitive inhibitor ethacrynic acid elicited strong kinetic cooperativity in the glutathione saturation of GST P1-1. Apparently, ethacrynic acid serves as an allosteric inhibitor of the enzyme. Conclusion and practical implications: In their own right, the compounds investigated are less potent than desired for adjuvants in cancer chemotherapy, but the structures of the most potent inhibitors could serve as leads for the synthesis of more efficient adjuvants.
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| 8. |
- Musdal, Yaman, et al.
(författare)
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Inhibition of human glutathione transferase P1-1 by novel benzazole derivatives
- 2012
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Ingår i: Türk Biyokimya Dergisi. - : LookUs Bilisim A.S.. - 0250-4685 .- 1303-829X. ; 37:4, s. 431-436
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Glutathione transferases (GST) are multifunctional enzymes involved in detoxication, drug resistance, cell signaling and apoptosis. The inhibitory effects of novel benzazole derivatives were tested on human GST P1-1 to find new agents for overcoming drug resistance in cancer cells.Methods: GST P1-1 was heterogously expressed in E. coli strain XL-1 Blue and purified using S-hexylglutathione-Sepharose 6B affinity chromatography. The effect of 33 potential inhibitors on enzymatic activity was assayed spectrophotometrically with 1-chloro-2,4-dinitrobenzene (CDNB) as well as with the alternative substrate phenethyl isothiocyanate (PEITC).Results: Compound-18 (N-[2-(4-chloro-benzyl)-benzooxazol-5-yl]-4- nitro-benzenesulfonamide) was the most potent inhibitor found with an IC50 value of approximately 10 μM with respect to CDNB and a somewhat less strong inhibitor (45 % inhibition at 40 μM) with PEITC as substrate. Compound-18 showed mixed inhibition with GSH and uncompetitive inhibition with CDNB with the Ki values 6.3 ± 0.7 μM and 11.8 ± 3.4 μM, respectively.Conclusion: Compound-18 is a potent inhibitor of GST P1-1. It may serve as a lead for further chemical modifications for increased potency. Additional studies will elucidate the effects of the inhibitor on cancer cells.
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| 9. |
- Musdal, Yaman, et al.
(författare)
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Potent GST Ketosteroid Isomerase Activity Relevant to Ecdysteroidogenesis in the Malaria Vector Anopheles gambiae
- 2023
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Ingår i: Biomolecules. - 2218-273X. ; 13:6
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Tidskriftsartikel (refereegranskat)abstract
- Nobo is a glutathione transferase (GST) crucially contributing to ecdysteroid biosynthesis in insects of the orders Diptera and Lepidoptera. Ecdysone is a vital steroid hormone in insects, which governs larval molting and metamorphosis, and the suppression of its synthesis has potential as a novel approach to insect growth regulation and combatting vectors of disease. In general, GSTs catalyze detoxication, whereas the specific function of Nobo in ecdysteroidogenesis is unknown. We report that Nobo from the malaria-spreading mosquito Anopheles gambiae is a highly efficient ketosteroid isomerase catalyzing double-bond isomerization in the steroids 5-androsten-3,17-dione and 5-pregnen-3,20-dione. These mammalian ketosteroids are unknown in mosquitoes, but the discovered prominent catalytic activity of these compounds suggests that the unknown Nobo substrate in insects has a ketosteroid functionality. Aminoacid residue Asp111 in Nobo is essential for activity with the steroids, but not for conventional GST substrates. Further characterization of Nobo may guide the development of new insecticides to prevent malaria.
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| 10. |
- Musdal, Yaman, et al.
(författare)
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Substrate specificities of two tau class glutathione transferases inducible by 2,4,6-trinitrotoluene in poplar
- 2015
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Ingår i: Biochimica et Biophysica Acta - General Subjects. - : Elsevier BV. - 0304-4165 .- 1872-8006. ; 1850:9, s. 1877-1883
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Tidskriftsartikel (refereegranskat)abstract
- Background: The genome of poplar (Populus trichocarpa) encodes 81 glutathione transferases (GSTs) annotated in eight distinct classes. The tau class is considered the most versatile in the biotransformation of xenobiotics and is composed of 58 GSTs. Two of the enzymes, GSTU16 and GSTU45, have particular interest since their expression is induced by exposure of poplar tissues to 2,4,6-trinitrotoluene (TNT) and could potentially be involved in the metabolism of this toxic environmental contaminant.Results: DNA encoding these GSTs was synthesized and the proteins were heterologously expressed in Escherichia coli and the purified enzymes were characterized.Major conclusions: GSTU16 assayed with a number of conventional GST substrates showed the highest specific activity (60 mu mol min(-1) mg(-1)) with phenethyl isothiocyanate, 150-fold higher than that with CDNB. By contrast, GSTU45 showed CDNB as the most active substrate (3.3 mu mol min(-1) mg(-1)) whereas all of the 16 alternative substrates tested yielded significantly lower activities. Homology modeling suggested that the aromatic residues Phe10 and Tyr107 in the active site of GSTU16 are promoting the high activity with PEITC and other substrates with aromatic side-chains. Nonetheless, TNT was a poor substrate for GSTU16 as well as for GSTU45 with a specific activity of 0.05 nmol min(-1) mg(-1) for both enzymes. General significance: GSTU16 and GSTU45 do not play a major role in the degradation of TNT in poplar.
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