The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Terry K Smith - One of the best experts on this subject based on the ideXlab platform.
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synthesis and biological evaluation of ctp synthetase inhibitors as potential agents for the treatment of african trypanosomiasis
ChemMedChem, 2012Co-Authors: Lucia Tamborini, Sandro Cosconati, Leonardo Lo Presti, Michael C. Iannuzzi, Terry K Smith, Luciana Marinelli, Andrea Pinto, Ettore Novellino, Louise L. Major, Pui E WongAbstract:Acivicin analogues with an increased affinity for CTP synthetase (CTPS) were designed as potential new trypanocidal agents. The inhibitory activity against CTPS can be improved by increasing the molecular complexity, by inserting groups able to establish additional interaction with the binding pocket of the enzyme. This strategy has been pursued with the synthesis of α-amino-substituted analogues of Acivicin and N1-substituted-pyrazoline derivatives. In general, there is a direct correlation between the enzymatic activity and the in vitro anti-trypanosomal efficacy of the derivatives studied here. However, this cannot be taken as a general rule, since other important factors may play a role, notably the ability of uptake / diffusion of the molecules into the trypanosomes.
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synthesis and in vitro in vivo evaluation of the antitrypanosomal activity of 3 bromoAcivicin a potent ctp synthetase inhibitor
ChemMedChem, 2011Co-Authors: Paola Conti, Pui E Wong, Michael C. Iannuzzi, Michael P. Barrett, Carlo De Micheli, Lucia Tamborini, Andrea Pinto, Louise L. Major, Terry K SmithAbstract:The first convenient synthesis of enantiomerically pure (αS,5S)-α-amino-3-bromo-4,5-dihydroisoxazol-5-yl acetic acid (3-bromoAcivicin) is described. We demonstrate that 3-bromoAcivicin is a CTP synthetase inhibitor three times as potent as its 3-chloro analogue, the natural antibiotic Acivicin. Because CTP synthetase was suggested to be a potential drug target in African trypanosomes, the in vitro/in vivo antitrypanosomal activity of 3-bromoAcivicin was assessed in comparison with Acivicin. Beyond expectation, we observed a 12-fold enhancement in the in vitro antitrypanosomal activity, while toxicity against mammalian cells remained unaffected. Despite its good in vitro activity and selectivity, 3-bromoAcivicin proved to be trypanostatic and failed to completely eradicate the infection when tested in vivo at its maximum tolerable dose.
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different sites of Acivicin binding and inactivation of gamma glutamyl transpeptidases
Proceedings of the National Academy of Sciences of the United States of America, 1995Co-Authors: Terry K Smith, Yoshitaka Ikeda, Junichi Fujii, Naoyuki Taniguchi, Alton MeisterAbstract:Acivicin is a potent inhibitor of gamma-glutamyl transpeptidase (EC 2.3.2.2), an enzyme of importance in glutathione metabolism. Acivicin inhibition and binding are prevented by gamma-glutamyl substrates and analogs (e.g., serine plus borate), consistent with the previous postulate that Acivicin and substrates bind to the same enzyme site. Inactivation of rat kidney transpeptidase by Acivicin leads to its binding as an ester to Thr-523. The pig enzyme, which has Ala-523 in place of Thr-523, is inhibited by Acivicin with esterification at Ser-405. The human enzyme has Thr-524 (corresponding to Thr-523 in rat); its inactivation leads to esterification of Ser-406 (corresponding to Ser-405 in rat and pig). Hydroxylamine treatment of the Acivicin-inactivated enzymes restores activity and releases the Acivicin-derived threo-beta-hydroxyglutamate moiety. The findings indicate that there are significant structural differences between the active site region of the rat enzyme and the active site regions of the human and pig. Human mutant enzymes in which Thr-524 and Ser-406 were replaced by Ala, separately and together, are enzymatically active, indicating that these amino acid residues are not required for catalysis. However, esterification of these residues (and of another near the active site) effectively blocks the active site or hinders its function. Acivicin can bind at enzyme sites that are close to that at which gamma-glutamylation occurs; it may bind at the latter site and then be transesterified to another enzyme site.
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interaction of gamma glutamyl transpeptidase with Acivicin
Journal of Biological Chemistry, 1994Co-Authors: E Stole, Terry K Smith, J M Manning, Alton MeisterAbstract:Inactivation of gamma-glutamyl transpeptidase by Acivicin (L-(alpha S,5S)-alpha-amino-3-chloro-4,5-dihydro-5-isoxazole acetic acid) is rapid, thought to be irreversible, and associated with binding of close to 1 mol of inhibitor/mol of enzyme. Previous studies with [3-14C]Acivicin indicated binding (prevented by substrate) to a specific hydroxyl group (threonine 523) of the rat kidney enzyme. In the present work, we found that such inactivation can be reversed by treating the inhibited enzyme with hydroxylamine. Reactivation (more than 85% complete) is associated with release from the inactivated enzyme of compounds that exhibit the properties of threo-beta-hydroxy-L-gamma-glutamyl hydroxamate and 3-hydroxypyrrolidone-2-carboxylate. We found that the enzyme acts very slowly on Acivicin, at a rate that is about 10(-9) that of its normal catalytic rate with glutathione, to form threo-beta-hydroxy-L-glutamate and hydroxylamine. The findings indicate that inhibition by Acivicin involves its transformation on the enzyme to an inhibitory species which is attached, apparently by ester linkage, to a specific hydroxyl group of the enzyme. The very slow rate of release of this intermediate appears to account for the observed inhibition.
S N Mason - One of the best experts on this subject based on the ideXlab platform.
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inhibition of tumor necrosis factor alpha tnf alpha and interleukin 1 beta il 1 beta messenger rna mrna expression in hl 60 leukemia cells by pentoxifylline and dexamethasone dissociation of Acivicin induced tnf alpha and il 1 beta mrna expression fr
Blood, 1992Co-Authors: J B Weinberg, S N Mason, T S WorthamAbstract:We have previously noted that the glutamine antagonist Acivicin (alpha S,5S-alpha-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid) induces monocytoid differentiation of freshly isolated human myeloid leukemia cells and cells of the myeloid leukemia cell line HL-60, and that the differentiation is accompanied by increases in expression of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta). Because we also showed that TNF-alpha and IL-1 beta can act synergistically to cause monocytoid differentiation of HL-60 cells, we hypothesized that Acivicin-induced TNF-alpha and IL-1 beta, in an autocrine manner, caused the differentiation. The purpose of the present study was to determine the causal roles of TNF-alpha and IL-1 beta in the Acivicin-induced differentiation of HL-60 cells by the use of dexamethasone (DEX) and pentoxifylline (PTX), two drugs that effectively inhibit expression of TNF-alpha and IL-1 beta. Acivicin caused a monocytoid differentiation of the cells as manifest by diminished cell growth, morphologic maturation of the cells, increased ability to generate hydrogen peroxide in response to acute treatment with phorbol myristate acetate, and increased expression of nonspecific esterase and the surface antigens CD14 and CD11b. Acivicin treatment also caused the cells to have diminished steady-state expression of messenger RNA (mRNA) for c-myc and c-myb, and increased expression of mRNA for TNF-alpha and IL-1 beta. DEX and PTX did not alter cell growth, and did not block the Acivicin-induced block in growth. PTX caused a slight increase in nonspecific esterase expression, but DEX had no effect on this, and neither drug diminished the Acivicin-induced increase in nonspecific esterase. Although neither drug alone lessened the Acivicin enhancement of hydrogen peroxide production, DEX and PTX together reduced this. DEX did not modify the Acivicin-induced morphologic maturation of the cells, but PTX alone or PTX with DEX potentiated the Acivicin-induced increase in mature cells. Basal CD14 and CD11b expression were slightly reduced by DEX and PTX, but neither drug modified the Acivicin-induced increases. DEX and PTX reduced the Acivicin-induced increases in TNF-alpha and IL-1 beta mRNA expression, but they had little or no effect on the Acivicin-induced decreases in expression of mRNA for c-myc and c-myb. Thus, DEX and PTX effectively block the Acivicin-induced expression of TNF-alpha and IL-1 beta, but they have little influence on the Acivicin-induced differentiation process.(ABSTRACT TRUNCATED AT 250 WORDS)
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relationship of Acivicin induced monocytoid differentiation of human myeloid leukemia cells to Acivicin induced modulation of growth factor cytokine and protooncogene mrna expression
Cancer Research, 1991Co-Authors: J B Weinberg, S N MasonAbstract:We have previously noted that the glutamine antagonist Acivicin (α S ,5 S -α-amino-3-chloro-4,5-dihydro-5-isoxazoleacetic acid) induces monocytoid differentiation of freshly isolated human myeloid leukemia cells and HL-60 cells. This study was designed to determine the effects of Acivicin on the levels of HL-60 cell mRNA transcripts of several cytokines, growth factors, and protooncogenes implicated in the control of hematopoietic cell proliferation and differentiation. Control HL-60 cells did not express mRNA for granulocyte-colony-stimulating factor, granulocyte-macrophage-colony-stimulating factor, interleukin 3, or interleukin 6, and Acivicin or phorbol myristate acetate did not induce their expression. Phorbol myristate acetate reduced expression of c- myc , c- myb , and heat shock protein 70 and enhanced those of macrophagecolony-stimulating factor and c- fms . Acivicin caused a decreased expression of c- myc , and an increased expression of mRNA for interleukin 1β and tumor necrosis factor α (TNF-α). The drug also caused an initial increase in c- myb , followed by a subsequent decrease below baseline levels. Supernatants and lysates of Acivicin-treated HL-60 cells contained increased levels of interleukin 1β. Both TNF-α and interleukin 1β have been shown previously to influence hematopoietic cell differentiation. In our experiments, exogenous interleukin 1 added to HL-60 cells did not induce differentiation, but the combination of interleukin 1 and TNF synergistically enhanced the process. Pretreatment of the cells with TNF enhanced their responsiveness to subsequent treatment with interleukin 1. Our results demonstrate that the glutamine antagonist Acivicin modulates HL-60 cell expression of TNF-α, interleukin 1β, c- myc , and c- myb and suggest that interleukin 1β and TNF-α might (in an autocrine manner) cause the differentiation.
Pui E Wong - One of the best experts on this subject based on the ideXlab platform.
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synthesis and biological evaluation of ctp synthetase inhibitors as potential agents for the treatment of african trypanosomiasis
ChemMedChem, 2012Co-Authors: Lucia Tamborini, Sandro Cosconati, Leonardo Lo Presti, Michael C. Iannuzzi, Terry K Smith, Luciana Marinelli, Andrea Pinto, Ettore Novellino, Louise L. Major, Pui E WongAbstract:Acivicin analogues with an increased affinity for CTP synthetase (CTPS) were designed as potential new trypanocidal agents. The inhibitory activity against CTPS can be improved by increasing the molecular complexity, by inserting groups able to establish additional interaction with the binding pocket of the enzyme. This strategy has been pursued with the synthesis of α-amino-substituted analogues of Acivicin and N1-substituted-pyrazoline derivatives. In general, there is a direct correlation between the enzymatic activity and the in vitro anti-trypanosomal efficacy of the derivatives studied here. However, this cannot be taken as a general rule, since other important factors may play a role, notably the ability of uptake / diffusion of the molecules into the trypanosomes.
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synthesis and in vitro in vivo evaluation of the antitrypanosomal activity of 3 bromoAcivicin a potent ctp synthetase inhibitor
ChemMedChem, 2011Co-Authors: Paola Conti, Pui E Wong, Michael C. Iannuzzi, Michael P. Barrett, Carlo De Micheli, Lucia Tamborini, Andrea Pinto, Louise L. Major, Terry K SmithAbstract:The first convenient synthesis of enantiomerically pure (αS,5S)-α-amino-3-bromo-4,5-dihydroisoxazol-5-yl acetic acid (3-bromoAcivicin) is described. We demonstrate that 3-bromoAcivicin is a CTP synthetase inhibitor three times as potent as its 3-chloro analogue, the natural antibiotic Acivicin. Because CTP synthetase was suggested to be a potential drug target in African trypanosomes, the in vitro/in vivo antitrypanosomal activity of 3-bromoAcivicin was assessed in comparison with Acivicin. Beyond expectation, we observed a 12-fold enhancement in the in vitro antitrypanosomal activity, while toxicity against mammalian cells remained unaffected. Despite its good in vitro activity and selectivity, 3-bromoAcivicin proved to be trypanostatic and failed to completely eradicate the infection when tested in vivo at its maximum tolerable dose.
Lucia Tamborini - One of the best experts on this subject based on the ideXlab platform.
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synthesis and biological evaluation of ctp synthetase inhibitors as potential agents for the treatment of african trypanosomiasis
ChemMedChem, 2012Co-Authors: Lucia Tamborini, Sandro Cosconati, Leonardo Lo Presti, Michael C. Iannuzzi, Terry K Smith, Luciana Marinelli, Andrea Pinto, Ettore Novellino, Louise L. Major, Pui E WongAbstract:Acivicin analogues with an increased affinity for CTP synthetase (CTPS) were designed as potential new trypanocidal agents. The inhibitory activity against CTPS can be improved by increasing the molecular complexity, by inserting groups able to establish additional interaction with the binding pocket of the enzyme. This strategy has been pursued with the synthesis of α-amino-substituted analogues of Acivicin and N1-substituted-pyrazoline derivatives. In general, there is a direct correlation between the enzymatic activity and the in vitro anti-trypanosomal efficacy of the derivatives studied here. However, this cannot be taken as a general rule, since other important factors may play a role, notably the ability of uptake / diffusion of the molecules into the trypanosomes.
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synthesis and in vitro in vivo evaluation of the antitrypanosomal activity of 3 bromoAcivicin a potent ctp synthetase inhibitor
ChemMedChem, 2011Co-Authors: Paola Conti, Pui E Wong, Michael C. Iannuzzi, Michael P. Barrett, Carlo De Micheli, Lucia Tamborini, Andrea Pinto, Louise L. Major, Terry K SmithAbstract:The first convenient synthesis of enantiomerically pure (αS,5S)-α-amino-3-bromo-4,5-dihydroisoxazol-5-yl acetic acid (3-bromoAcivicin) is described. We demonstrate that 3-bromoAcivicin is a CTP synthetase inhibitor three times as potent as its 3-chloro analogue, the natural antibiotic Acivicin. Because CTP synthetase was suggested to be a potential drug target in African trypanosomes, the in vitro/in vivo antitrypanosomal activity of 3-bromoAcivicin was assessed in comparison with Acivicin. Beyond expectation, we observed a 12-fold enhancement in the in vitro antitrypanosomal activity, while toxicity against mammalian cells remained unaffected. Despite its good in vitro activity and selectivity, 3-bromoAcivicin proved to be trypanostatic and failed to completely eradicate the infection when tested in vivo at its maximum tolerable dose.
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a novel simplified synthesis of Acivicin
Tetrahedron-asymmetry, 2009Co-Authors: Andrea Pinto, Paola Conti, Lucia Tamborini, Carlo De MicheliAbstract:This report describes an efficient synthesis of the natural isomer of Acivicin, which is the only one provided with a noteworthy biological activity. The present procedure allowed the synthesis of (+)-1 in just five steps with a 34% overall yield. Due to the easy separation of the two diastereomers and to the availability of the starting material at low cost, the present procedure can be scaled-up to gram quantities.
Keiichi Fukuyama - One of the best experts on this subject based on the ideXlab platform.
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structure of bacillus subtilis γ glutamyl transpeptidase in complex with Acivicin diversity of the binding mode of a classical and electrophilic active site directed glutamate analogue
Acta Crystallographica Section D-biological Crystallography, 2014Co-Authors: Tomoyo Ida, Keiichi Fukuyama, Jun Hiratake, Hideyuki Suzuki, Kei WadaAbstract:γ-Glutamyltranspeptidase (GGT) is an enzyme that plays a central role in glutathione metabolism, and Acivicin is a classical inhibitor of GGT. Here, the structure of Acivicin bound to Bacillus subtilis GGT determined by X-ray crystallography to 1.8 A resolution is presented, in which it binds to the active site in a similar manner to that in Helicobacter pylori GGT, but in a different binding mode to that in Escherichia coli GGT. In B. subtilis GGT, Acivicin is bound covalently through its C3 atom with sp2 hybridization to Thr403 Oγ, the catalytic nucleophile of the enzyme. The results show that Acivicin-binding sites are common, but the binding manners and orientations of its five-membered dihydroisoxazole ring are diverse in the binding pockets of GGTs.
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crystal structures of escherichia coli gamma glutamyltranspeptidase in complex with azaserine and Acivicin novel mechanistic implication for inhibition by glutamine antagonists
Journal of Molecular Biology, 2008Co-Authors: Kei Wada, Hidehiko Kumagai, Jun Hiratake, Machiko Irie, Toshihiro Okada, Chiaki Yamada, Hideyuki Suzuki, Keiichi FukuyamaAbstract:Abstract γ-Glutamyltranspeptidase (GGT) catalyzes the cleavage of such γ-glutamyl compounds as glutathione, and the transfer of their γ-glutamyl group to water or to other amino acids and peptides. GGT is involved in a number of biological phenomena such as drug resistance and metastasis of cancer cells by detoxification of xenobiotics. Azaserine and Acivicin are classical and irreversible inhibitors of GGT, but their binding sites and the inhibition mechanisms remain to be defined. We have determined the crystal structures of GGT from Escherichia coli in complex with azaserine and Acivicin at 1.65 A resolution. Both inhibitors are bound to GGT at its substrate-binding pocket in a manner similar to that observed previously with the γ-glutamyl-enzyme intermediate. They form a covalent bond with the O γ atom of Thr391, the catalytic residue of GGT. Their α-carboxy and α-amino groups are recognized by extensive hydrogen bonding and charge interactions with the residues that are conserved among GGT orthologs. The two amido nitrogen atoms of Gly483 and Gly484, which form the oxyanion hole, interact with the inhibitors directly or via a water molecule. Notably, in the azaserine complex the carbon atom that forms a covalent bond with Thr391 is sp 3 -hybridized, suggesting that the carbonyl of azaserine is attacked by Thr391 to form a tetrahedral intermediate, which is stabilized by the oxyanion hole. Furthermore, when Acivicin is bound to GGT, a migration of the single and double bonds occurs in its dihydroisoxazole ring. The structural characteristics presented here imply that the unprecedented binding modes of azaserine and Acivicin are conserved in all GGTs from bacteria to mammals and give a new insight into the inhibition mechanism of glutamine amidotransferases by these glutamine antagonists.
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crystal structures of escherichia coli gamma glutamyltranspeptidase in complex with azaserine and Acivicin novel mechanistic implication for inhibition by glutamine antagonists
Journal of Molecular Biology, 2008Co-Authors: Kei Wada, Hidehiko Kumagai, Jun Hiratake, Machiko Irie, Toshihiro Okada, Chiaki Yamada, Hideyuki Suzuki, Keiichi FukuyamaAbstract:Abstract γ-Glutamyltranspeptidase (GGT) catalyzes the cleavage of such γ-glutamyl compounds as glutathione, and the transfer of their γ-glutamyl group to water or to other amino acids and peptides. GGT is involved in a number of biological phenomena such as drug resistance and metastasis of cancer cells by detoxification of xenobiotics. Azaserine and Acivicin are classical and irreversible inhibitors of GGT, but their binding sites and the inhibition mechanisms remain to be defined. We have determined the crystal structures of GGT from Escherichia coli in complex with azaserine and Acivicin at 1.65 A resolution. Both inhibitors are bound to GGT at its substrate-binding pocket in a manner similar to that observed previously with the γ-glutamyl-enzyme intermediate. They form a covalent bond with the O γ atom of Thr391, the catalytic residue of GGT. Their α-carboxy and α-amino groups are recognized by extensive hydrogen bonding and charge interactions with the residues that are conserved among GGT orthologs. The two amido nitrogen atoms of Gly483 and Gly484, which form the oxyanion hole, interact with the inhibitors directly or via a water molecule. Notably, in the azaserine complex the carbon atom that forms a covalent bond with Thr391 is sp 3 -hybridized, suggesting that the carbonyl of azaserine is attacked by Thr391 to form a tetrahedral intermediate, which is stabilized by the oxyanion hole. Furthermore, when Acivicin is bound to GGT, a migration of the single and double bonds occurs in its dihydroisoxazole ring. The structural characteristics presented here imply that the unprecedented binding modes of azaserine and Acivicin are conserved in all GGTs from bacteria to mammals and give a new insight into the inhibition mechanism of glutamine amidotransferases by these glutamine antagonists.
