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Block E, Booker SJ, Flores-Penalba S, George GN, Gundala S, Landgraf BJ, Liu J, Lodge SN, Pushie MJ, Rozovsky S, Vattekkatte A, Yaghi R, Zeng H. Trifluoroselenomethionine: A New Unnatural Amino Acid. Chembiochem 2016; 17:1738-51. [PMID: 27383291 PMCID: PMC5373900 DOI: 10.1002/cbic.201600266] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Indexed: 11/10/2022]
Abstract
Trifluoroselenomethionine (TFSeM), a new unnatural amino acid, was synthesized in seven steps from N-(tert-butoxycarbonyl)-l-aspartic acid tert-butyl ester. TFSeM shows enhanced methioninase-induced cytotoxicity, relative to selenomethionine (SeM), toward HCT-116 cells derived from human colon cancer. Mechanistic explanations for this enhanced activity are computationally and experimentally examined. Comparison of TFSeM and SeM by selenium EXAFS and DFT calculations showed them to be spectroscopically and structurally very similar. Nonetheless, when two different variants of the protein GB1 were expressed in an Escherichia coli methionine auxotroph cell line in the presence of TFSeM and methionine (Met) in a 9:1 molar ratio, it was found that, surprisingly, 85 % of the proteins contained SeM residues, even though no SeM had been added, thus implying loss of the trifluoromethyl group from TFSeM. The transformation of TFSeM into SeM is enzymatically catalyzed by E. coli extracts, but TFSeM is not a substrate of E. coli methionine adenosyltransferase.
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Affiliation(s)
- Eric Block
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Ave., Albany, NY, 12222, USA.
| | - Squire J Booker
- Department of Chemistry, The Pennsylvania State University, 302 Chemistry Building, University Park, PA, 16802, USA
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Sonia Flores-Penalba
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Ave., Albany, NY, 12222, USA
| | - Graham N George
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan, S7N 5E2, Canada
| | - Sivaji Gundala
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Ave., Albany, NY, 12222, USA
| | - Bradley J Landgraf
- Department of Chemistry, The Pennsylvania State University, 302 Chemistry Building, University Park, PA, 16802, USA
| | - Jun Liu
- Department of Chemistry and Biochemistry, University of Delaware, 163 The Green, Newark, DE, 19716, USA
| | - Stephene N Lodge
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Ave., Albany, NY, 12222, USA
| | - M Jake Pushie
- Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan, S7N 5E2, Canada
- College of Medicine, University of Saskatchewan, 107 Wiggins Road, Saskatoon, Saskatchewan, S7N 5E5, Canada
| | - Sharon Rozovsky
- Department of Chemistry and Biochemistry, University of Delaware, 163 The Green, Newark, DE, 19716, USA.
| | - Abith Vattekkatte
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Ave., Albany, NY, 12222, USA
- Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Hans Knoll Strasse 8, 07745, Jena, Germany
| | - Rama Yaghi
- Department of Chemistry, University at Albany, State University of New York, 1400 Washington Ave., Albany, NY, 12222, USA
- Atlanta Metropolitan State College, 1630 Metropolitan Parkway SW, Atlanta, GA, 30310, USA
| | - Huawei Zeng
- United States Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, 2420 2nd Avenue North, Grand Forks, ND, 58203, USA
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2
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Bothwell IR, Luo M. Large-scale, protection-free synthesis of Se-adenosyl-L-selenomethionine analogues and their application as cofactor surrogates of methyltransferases. Org Lett 2014; 16:3056-9. [PMID: 24852128 PMCID: PMC4059250 DOI: 10.1021/ol501169y] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Indexed: 12/26/2022]
Abstract
S-adenosyl-L-methionine (SAM) analogues have previously demonstrated their utility as chemical reporters of methyltransferases. Here we describe the facile, large-scale synthesis of Se-alkyl Se-adenosyl-L-selenomethionine (SeAM) analogues and their precursor, Se-adenosyl-L-selenohomocysteine (SeAH). Comparison of SeAM analogues with their equivalent SAM analogues suggests that sulfonium-to-selenonium substitution can enhance their compatibility with certain protein methyltransferases, favoring otherwise less reactive SAM analogues. Ready access to SeAH therefore enables further application of SeAM analogues as chemical reporters of diverse methyltransferases.
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Affiliation(s)
- Ian R. Bothwell
- Molecular Pharmacology
and Chemistry Program and Tri-Institutional Training Program
in Chemical Biology, Memorial Sloan Kettering
Cancer Center, New York, New York 10065, United
States
| | - Minkui Luo
- Molecular Pharmacology
and Chemistry Program and Tri-Institutional Training Program
in Chemical Biology, Memorial Sloan Kettering
Cancer Center, New York, New York 10065, United
States
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3
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Bothwell IR, Islam K, Chen Y, Zheng W, Blum G, Deng H, Luo M. Se-adenosyl-L-selenomethionine cofactor analogue as a reporter of protein methylation. J Am Chem Soc 2012; 134:14905-12. [PMID: 22917021 PMCID: PMC3458307 DOI: 10.1021/ja304782r] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Posttranslational methylation by S-adenosyl-L-methionine(SAM)-dependent methyltransferases plays essential roles in modulating protein function in both normal and disease states. As such, there is a growing need to develop chemical reporters to examine the physiological and pathological roles of protein methyltransferases. Several sterically bulky SAM analogues have previously been used to label substrates of specific protein methyltransferases. However, broad application of these compounds has been limited by their general incompatibility with native enzymes. Here we report a SAM surrogate, ProSeAM (propargylic Se-adenosyl-l-selenomethionine), as a reporter of methyltransferases. ProSeAM can be processed by multiple protein methyltransferases for substrate labeling. In contrast, sulfur-based propargylic SAM undergoes rapid decomposition at physiological pH, likely via an allene intermediate. In conjunction with fluorescent/affinity-based azide probes, copper-catalyzed azide-alkyne cycloaddition chemistry, in-gel fluorescence visualization and proteomic analysis, we further demonstrated ProSeAM's utility to profile substrates of endogenous methyltransferases in diverse cellular contexts. These results thus feature ProSeAM as a convenient probe to study the activities of endogenous protein methyltransferases.
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Affiliation(s)
- Ian R. Bothwell
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065
- Tri-Institutional Training Program in Chemical Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065
| | - Kabirul Islam
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065
| | - Yuling Chen
- School of Life Sciences, Tsinghua University, Beijing, China 100084
| | - Weihong Zheng
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065
| | - Gil Blum
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065
- Tri-Institutional Training Program in Chemical Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065
| | - Haiteng Deng
- School of Life Sciences, Tsinghua University, Beijing, China 100084
| | - Minkui Luo
- Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065
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Abstract
S-Adenosyl-L-methionine (AdoMet) is one of Nature's most diverse metabolites, used not only in a large number of biological reactions but amenable to several different modes of reactivity. The types of transformations in which it is involved include decarboxylation, electrophilic addition to any of the three carbons bonded to the central sulfur atom, proton removal at carbons adjacent to the sulfonium, and reductive cleavage to generate 5'-deoxyadenosyl 5'-radical intermediates. At physiological pH and temperature, AdoMet is subject to three spontaneous degradation pathways, the first of which is racemization of the chiral sulfonium group, which takes place in a pH-independent manner. The two remaining pathways are pH-dependent and include (1) intramolecular attack of the alpha-carboxylate group onto the gamma-carbon, affording L-homoserine lactone (HSL) and 5'-methylthioadenosine (MTA), and (2) deprotonation at C-5', initiating a cascade that results in formation of adenine and S-ribosylmethionine. Herein, we describe pH-dependent stability studies of AdoMet and its selenium and tellurium analogues, Se-adenosyl-L-selenomethionine and Te-adenosyl-L-telluromethionine (SeAdoMet and TeAdoMet, respectively), at 37 degrees C and constant ionic strength, which we use as a probe of their relative intrinsic reactivities. We find that with AdoMet intramolecular nucleophilic attack to afford HSL and MTA exhibits a pH-rate profile having two titratable groups with apparent pK(a) values of 1.2 +/- 0.4 and 8.2 +/- 0.05 and displaying first-order rate constants of <0.7 x 10(-6) s(-1) at pH values less than 0.5, approximately 3 x 10(-6) s(-1) at pH values between 2 and 7, and approximately 15 x 10(-6) s(-1) at pH values greater than 9. Degradation via deprotonation at C-5' follows a pH-rate profile having one titratable group with an apparent pK(a) value of approximately 11.5. The selenium analogue decays significantly faster via intramolecular nucleophilic attack, also exhibiting a pH-rate profile with two titratable groups with pK(a) values of approximately 0.86 and 8.0 +/- 0.1 with first-order rate constants of <7 x 10(-6) s(-1) at pH values less than 0.9, approximately 32 x 10(-6) s(-1) at pH values between 2 and 7, and approximately 170 x 10(-6) s(-1) at pH values greater than 9. Degradation via deprotonation at C-5' proceeds with one titratable group displaying an apparent pK(a) value of approximately 14.1. Unexpectedly, TeAdoMet did not decay at an observable rate via either of these two pathways. Last, enzymatically synthesized AdoMet was found to racemize at rates that were consistent with earlier studies (Hoffman, J. L. (1986) Biochemistry 25, 4444-4449); however, SeAdoMet and TeAdoMet did not racemize at detectable rates. In the accompanying paper, we use the information obtained in these model studies to probe the mechanism of cyclopropane fatty acid synthase via use of the onium chalcogens of AdoMet as methyl donors.
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Affiliation(s)
- David F Iwig
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Fassbender M, de Villiers D, Nortier M, van der Walt N. The natBr(p,x) (73,75)Se nuclear processes: a convenient route for the production of radioselenium tracers relevant to amino acid labelling. Appl Radiat Isot 2001; 54:905-13. [PMID: 11300403 DOI: 10.1016/s0969-8043(00)00359-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A possible route for the production of no-carrier-added (n.c.a.) 73Se (T(1/2) = 7.1 h) and 75Se (120 d) is introduced. D,L-2-Amino-4-([73Se]methyl-seleno) butanoic acid (D,L-[73Se]selenomethionine) with an overall radiochemical yield of > 40% could be prepared via a 3-step polymer-supported synthesis after successful separation of 73Se from KBr targets. Excitation functions for the natBr(p,x) (72,73,75)Se processes were measured from threshold up to 100 MeV utilizing pellets of pressed KBr. Targets were irradiated at the NAC cyclotron with proton beams having primary energies of 40.4, 66.8 and 100.9 MeV. The calculated 73Se yield (EOB) for 1 h irradiation in 1 microA of beam at the optimum proton energy range of 62-->42 MeV is 81.4 MBq (2.2 mCi), and the calculated 75Se yield (EOB) for the overall range 62 MeV-->threshold for the same irradiation conditions is 0.97 MBq (0.026 mCi).
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Affiliation(s)
- M Fassbender
- National Accelerator Centre, Faure, South Africa.
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Kochansky JP, Tschursin E, Lusby WR, Lacroix D, Wolf WR. Synthesis of a selenomethionine peptide and a preliminary study of transport into Escherichia coli monitored by high-performance liquid chromatography. Int J Pept Protein Res 1995; 45:17-25. [PMID: 7775005 DOI: 10.1111/j.1399-3011.1995.tb01563.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The tripeptide Gly-SeMet-Gly has been synthesized by a combination of solution and solid-phase methods. Increase in weight of the resin was very nearly theoretical, and purification was straightforward. Its absorption was compared to that of the corresponding peptide, Gly-Met-Gly, in E. coli using HPLC ion-exchange separation and fluorometric determination of the disappearance of peptides in the culture medium and the appearance of methionine and selenomethionine in the same culture medium. As E. coli are not known to possess extracellular peptidases, and in fact have been shown to possess transport systems for peptides, this absorption is interpreted as transport of the peptide through the cell wall and membrane into the cytoplasm, endohydrolysis of the peptide, and efflux of the peptides' amino acids. Uptake of both peptides was approximately equal, but was slowed when both peptides were present simultaneously.
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Affiliation(s)
- J P Kochansky
- Insect Neurobiology and Hormone Laboratory, US Department of Agriculture, Beltsville, Maryland, USA
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Affiliation(s)
- J Römer
- Zentralinstitut für Kernforschung Rossendorf, Dresden, Fed. Rep. Germany
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Abstract
A method is described for the synthesis and purification of the photoaffinity label Se-(8-azidoadenosyl)[75Se]selenomethionine. This photoaffinity label can be used to specifically and covalently label the S-adenosylmethionine binding site of proteins that use this cofactor, as exemplified by labeling of thioether methyltransferase. By utilizing the gamma-emitting isotope of selenium, Se-(8-azidoadenosyl)[75Se]selenomethionine eliminates the need for the impregnation of acrylamide gels with fluorographic enhancers and dilution of liquid samples into scintillation cocktails, as is required with the commonly used methyl-3H-labeled and 35S-labeled S-(8-azidoadenosyl)methionine.
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Affiliation(s)
- D R Warner
- University of Louisville, Department of Biochemistry, Kentucky 40292
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9
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Plenevaux A, Guillaume M, Brihaye C, Lemaire C, Cantineau R. Chemical processing for production of no-carrier-added selenium-73 from germanium and arsenic targets and synthesis of L-2-amino-4-([73Se]methylseleno) butyric acid (L-[73Se]selenomethionine). Int J Rad Appl Instrum A 1990; 41:829-38. [PMID: 2176191 DOI: 10.1016/0883-2889(90)90060-t] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The Ge(4He, xn) and 75As(p, 3n) reactions were compared as the best potential routes for routine production of selenium-73 (73Se) for medical applications. With 26 MeV alpha particles, available with compact cyclotrons, the first reaction required an enriched 70Ge target of sodium metagermanate to give a production yield of 1 mCi/microAh (0.037 GBq/microAh) in a 105 mg/cm2 target. With 55 MeV protons the As(p, 3n) reaction on natural arsenic yielded 20 mCi/microAh (0.74 GBq/microAh) in a 685 mg/cm2 target. A simple method was developed and optimized for both targets in order to isolate and purify the no-carrier-added selenium in the elemental form with a radiochemical yield greater than 75% in less than 90 min. An automated radiochemical processing unit has been designed for the routine production of 100-150 mCi (3.7-5.5 GBq) batches of carrier-free 73Se ready for radiopharmaceutical labeling. 30 mCi (1.11 GBq) (EOS) of L-2-amino-4-([73Se]methylseleno) butyric acid (L-[73Se]selenomethionine) ready for injection with a specific activity of 5 Ci/mmol (185 GBq/mmol) (EOS) were obtained through a fast chemical synthesis. Radiation absorbed dose estimates for L-[73Se]selenomethionine have been determined. A value of 0.70 rem/mCi (0.19 mSv/MBq) administered was calculated for the risk from irradiation in man. The first human PET investigation with [73Se]selenomethionine showed a very good delineation between liver and pancreas.
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Affiliation(s)
- A Plenevaux
- Cyclotron Research Center, Liège University, Belgium
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Abstract
This paper describes the enzymatic synthesis of selenomethionine metabolites of the transmethylation and polyamine synthesis pathways: adenosylselenomethionine, adenosylselenohomocysteine, decarboxylated adenosylselenomethionine, and methylselenoadenosine. These compounds and the corresponding methionine metabolites were simultaneously separated by a single HPLC run. The sensitivity of the HPLC method is about 20 pmol per compound. The method may be used for direct analysis of the metabolite levels in tissues or cells treated with selenomethionine and it provides an assay method for the pulse-chase type of analysis of relative flows for both selenium- and sulfur-containing compounds in transmethylation and polyamine pathways.
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Affiliation(s)
- E O Kajander
- Department of Biochemistry, University of Kuopio, Finland
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Plenevaux A, Cantineau R, Guillaume M, Christiaens L, Tihange G. Fast chemical synthesis of [75Se]L-selenomethionine. Int J Rad Appl Instrum A 1987; 38:59-61. [PMID: 3030968 DOI: 10.1016/0883-2889(87)90237-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
A fast chemical synthesis of high specific activity [75Se]L-selenomethionine (10 Ci/mmol--370 GBq/mmol) is described with a view to 73Se labeling and PET studies. The overall radiochemical yield of the preparation is better than 80%. The purification method uses commercially available reverse phase HPLC columns and 9% NaCl as mobile phase. The final labeled compound is obtained in less than 3 h and the chemical, radiochemical and optical purities of the L-isomer are higher than 99.0%.
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