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Bionda N, Pitteloud JP, Cudic P. Solid-phase synthesis of fusaricidin/LI-F class of cyclic lipopeptides: Guanidinylation of resin-bound peptidyl amines. Biopolymers 2016; 100:160-6. [PMID: 23436339 DOI: 10.1002/bip.22186] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 11/02/2012] [Accepted: 11/12/2012] [Indexed: 01/20/2023]
Abstract
Fusaricidins/LI-Fs and related cyclic lipopeptides represent an interesting new class of antibacterial peptides with the potential to meet the challenge of antibiotic resistance in bacteria. Our previous study (Bionda et al. ChemMedChem 2012, 7, 871-882) revealed the significance of the guanidinium group located at the termini of the lipidic tails of these cyclic lipopeptides for their antibacterial activities. Therefore, devising a synthetic strategy that will allow incorporation of guanidinium functionality into their structure is of particular practical importance. Since appropriately protected guanidino fatty acid building blocks are not commercially available, our strategy toward guanidinylated fusaricidin/LI-F analogs include solid-phase synthesis of a cyclic lipopeptide precursor possessing a lipidic tail with a terminal amino group followed by its conversion into corresponding guanidine. To find the optimal method for this conversion, we have examined commonly used guanidinylation reagents under the conditions compatible with standard solid-phase peptide synthesis. Described experimental results demonstrated superiority of N,N'-di-Boc-N″-triflylguanidine in solid-phase preparation of fusaricidin/LI-F class of cyclic lipopeptides. The triflylguanidine reagent gave a single monoguanidinylated product in excellent yield independently of the type of solid-support.
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Affiliation(s)
- Nina Bionda
- Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL, 34987; Department of Chemistry and Biochemistry, Florida Atlantic University, Boca Raton, FL, 33431
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Rodriguez MC, Yegorova S, Pitteloud JP, Chavaroche AE, André S, Ardá A, Minond D, Jiménez-Barbero J, Gabius HJ, Cudic M. Thermodynamic Switch in Binding of Adhesion/Growth Regulatory Human Galectin-3 to Tumor-Associated TF Antigen (CD176) and MUC1 Glycopeptides. Biochemistry 2015; 54:4462-74. [PMID: 26129647 PMCID: PMC4520625 DOI: 10.1021/acs.biochem.5b00555] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
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A shift
to short-chain glycans is an observed change in mucin-type
O-glycosylation in premalignant and malignant epithelia. Given the
evidence that human galectin-3 can interact with mucins and also weakly
with free tumor-associated Thomsen-Friedenreich (TF) antigen (CD176),
the study of its interaction with MUC1 (glyco)peptides is of biomedical
relevance. Glycosylated MUC1 fragments that carry the TF antigen attached
through either Thr or Ser side chains were synthesized using standard
Fmoc-based automated solid-phase peptide chemistry. The dissociation
constants (Kd) for interaction of galectin-3
and the glycosylated MUC1 fragments measured by isothermal titration
calorimetry decreased up to 10 times in comparison to that of the
free TF disaccharide. No binding was observed for the nonglycosylated
control version of the MUC1 peptide. The most notable feature of the
binding of MUC1 glycopeptides to galectin-3 was a shift from a favorable
enthalpy to an entropy-driven binding process. The comparatively diminished
enthalpy contribution to the free energy (ΔG) was compensated by a considerable gain in the entropic term. 1H–15N heteronuclear single-quantum coherence
spectroscopy nuclear magnetic resonance data reveal contact at the
canonical site mainly by the glycan moiety of the MUC1 glycopeptide.
Ligand-dependent differences in binding affinities were also confirmed
by a novel assay for screening of low-affinity glycan–lectin
interactions based on AlphaScreen technology. Another key finding
is that the glycosylated MUC1 peptides exhibited activity in a concentration-dependent
manner in cell-based assays revealing selectivity among human galectins.
Thus, the presentation of this tumor-associated carbohydrate ligand
by the natural peptide scaffold enhances its affinity, highlighting
the significance of model studies of human lectins with synthetic
glycopeptides.
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Affiliation(s)
- Maria C Rodriguez
- †Department of Chemistry and Biochemistry, Charles E. Schmidt College of Science, Florida Atlantic University, 777 Glades Road, Boca Raton, Florida 33431, United States.,‡Torrey Pines Institute for Molecular Studies, 11350 Southwest Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Svetlana Yegorova
- ‡Torrey Pines Institute for Molecular Studies, 11350 Southwest Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Jean-Philippe Pitteloud
- ‡Torrey Pines Institute for Molecular Studies, 11350 Southwest Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Anais E Chavaroche
- ‡Torrey Pines Institute for Molecular Studies, 11350 Southwest Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Sabine André
- §Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians-University, Veterinärstrasse 13, 80539 Munich, Germany
| | - Ana Ardá
- ∥CIC bioGUNE, Bizkaia Technological Park, Building 801 A, 48160 Derio, Spain
| | - Dimitriy Minond
- ‡Torrey Pines Institute for Molecular Studies, 11350 Southwest Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Jesús Jiménez-Barbero
- ∥CIC bioGUNE, Bizkaia Technological Park, Building 801 A, 48160 Derio, Spain.,⊥Ikerbasque, Basque Foundation for Science, Maria Lopez de Haro 3, 48013 Bilbao, Spain
| | - Hans-Joachim Gabius
- §Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians-University, Veterinärstrasse 13, 80539 Munich, Germany
| | - Mare Cudic
- †Department of Chemistry and Biochemistry, Charles E. Schmidt College of Science, Florida Atlantic University, 777 Glades Road, Boca Raton, Florida 33431, United States
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Afzal MS, Pitteloud JP, Buccella D. Enhanced ratiometric fluorescent indicators for magnesium based on azoles of the heavier chalcogens. Chem Commun (Camb) 2015; 50:11358-61. [PMID: 25164869 DOI: 10.1039/c4cc04460f] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Red-shifted fluorescent indicators for magnesium were developed by incorporation of sulfur or selenium in the azole moiety of 'fura' fluorophores. Single atom replacement in the acceptor of these ITC probes affords longer excitation and emission wavelengths as well as greater separation between excitation bands, valuable for ratiometric intracellular Mg(2+) imaging.
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Affiliation(s)
- Mohammad S Afzal
- Department of Chemistry, New York University, New York, NY 10003, USA.
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Schwartz SC, Pinto-Pacheco B, Pitteloud JP, Buccella D. Formation of ternary complexes with MgATP: effects on the detection of Mg2+ in biological samples by bidentate fluorescent sensors. Inorg Chem 2014; 53:3204-9. [PMID: 24593871 PMCID: PMC3969098 DOI: 10.1021/ic5000606] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Fluorescent indicators based on β-keto-acid bidentate coordination motifs display superior metal selectivity profiles compared to current o-aminophenol-N,N,O-triacetic acid (APTRA) based chelators for the study of biological magnesium. These low denticity chelators, however, may allow for the formation of ternary complexes with Mg(2+) and common ligands present in the cellular milieu. In this work, absorption, fluorescence, and NMR spectroscopy were employed to study the interaction of turn-on and ratiometric fluorescent indicators based on 4-oxo-4H-quinolizine-3-carboxylic acid with Mg(2+) and ATP, the most abundant chelator of biological magnesium, thus revealing the formation of ternary complexes under conditions relevant to fluorescence imaging. The formation of ternary species elicits comparable or greater optical changes than those attributed to the formation of binary complexes alone. Dissociation of the fluorescent indicators from both ternary and binary species have apparent equilibrium constants in the low millimolar range at pH 7 and 25 °C. These results suggest that these bidentate sensors are incapable of distinguishing between free Mg(2+) and MgATP based on ratio or intensity-based steady-state fluorescence measurements, thus posing challenges in the interpretation of results from fluorescence imaging of magnesium in nucleotide-rich biological samples.
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Affiliation(s)
- Sarina C Schwartz
- Department of Chemistry, New York University , New York, New York 10003
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Liang Y, Pitteloud JP, Wnuk SF. Hydrogermylation of 5-ethynyluracil nucleosides: formation of 5-(2-germylvinyl)uracil and 5-(2-germylacetyl)uracil nucleosides. J Org Chem 2013; 78:5761-7. [PMID: 23631719 DOI: 10.1021/jo400590z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A stereoselective radical-mediated hydrogermylation of the protected 5-ethynyluracil nucleosides with trialkyl-, triaryl,- or tris(trimethylsilyl)germanes gave (Z)-5-(2-germylvinyl)uridine, 2'-deoxyuridine, or ara-uridine as major products. Reaction of the β-triphenylgermyl vinyl radical intermediate with oxygen and fragmentation of the resulting peroxyradical provided also 5-[2-(triphenylgermyl)acetyl]pyrimidine nucleosides in low to moderate yields. Thermal isomerization of the latter in MeOH occurred via a four-centered activated complex, and subsequent hydrolysis of the resulting O-germyl substituted enol yielded 5-acetyluracil nucleosides in quantitative yield.
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Affiliation(s)
- Yong Liang
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
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Pitteloud JP, Bionda N, Cudic P. Direct access to side chain N,N'-diaminoalkylated derivatives of basic amino acids suitable for solid-phase peptide synthesis. Amino Acids 2012; 44:321-33. [PMID: 22714010 DOI: 10.1007/s00726-012-1336-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/29/2012] [Indexed: 12/01/2022]
Abstract
A simple and efficient one-pot procedure that enables rapid access to orthogonally protected N,N'-diaminoalkylated basic amino acid building blocks fully compatible with standard Boc and Fmoc solid-phase peptide synthesis is reported. Described synthetic approach includes double reductive alkylation of N (α)-protected diamino acids with N-protected amino aldehydes in the presence of sodium cyanoborohydride. This approach allows preparation of symmetrical, as well as unsymmetrical, basic amino acid derivatives with branched side-chains that can be further modified, enhancing their synthetic utility. The suitability of the synthesized branched basic amino acid building blocks for use in standard solid-phase peptide synthesis has been demonstrated by synthesis of an indolicidin analogue in which the lysine residue was substituted with the synthetic derivative N (α)-(9H-fluorenyl-9-methoxycarbonyl)-N (β),N (β) '-bis[2-(tert-butoxycarbonylamino)ethyl]-L-2,3-diaminopropionic acid. This substitution resulted in an analogue with more ordered secondary structure in 2,2,2-trifluoroethanol and enhanced antibacterial activity without altering hemolytic activity.
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Affiliation(s)
- Jean-Philippe Pitteloud
- Torrey Pines Institute for Molecular Studies, 11350 SW Village Parkway, Port St Lucie, FL 34987, USA
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Pitteloud JP, Liang Y, Wnuk SF. Chemoselective Transfer of Allyl or Phenyl Group from Allyl(phenyl)germanes in Pd-catalyzed Reactions with Aryl Halides. CHEM LETT 2011. [DOI: 10.1246/cl.2011.967] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Pitteloud JP, Zhang ZT, Liang Y, Cabrera L, Wnuk SF. Fluoride-promoted cross-coupling of chloro(mono-, di-, or triphenyl)germanes with aryl halides in "moist" toluene. Multiple transfer of the phenyl group from organogermane substrates and comparison of the coupling efficiencies of chloro(phenyl)germanes with their corresponding stannane and silane counterparts. J Org Chem 2010; 75:8199-212. [PMID: 21067173 DOI: 10.1021/jo101848f] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The trichlorophenyl-, dichlorodiphenyl-, and chlorotriphenylgermanes undergo Pd-catalyzed cross-couplings with aryl bromides and iodides in the presence of tetrabutylammonium fluoride in toluene with addition of the measured amount of water. One chloride ligand on the Ge center allows efficient activation by fluoride to promote transfer of one, two, or three phenyl groups from the organogermanes. The corresponding chlorophenylstannanes were found to be more reactive than chlorophenylsilanes, which in turn were more effective than chlorophenylgermanes. One chloride ligand on the Ge or Si center allows efficient activation by fluoride to promote transfer of up to three aryl groups from germane or silicon. However, no haloligand was necessary to be present on the Sn center, since tetraphenyltin efficiently transferred up to four phenyl groups during fluoride-promoted couplings with aryl halides. (19)F NMR studies suggested formation of the fluorophenylgermanes and the hypervalent germanate species as possible intermediates.
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Affiliation(s)
- Jean-Philippe Pitteloud
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA
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Zhang ZT, Pitteloud JP, Cabrera L, Liang Y, Toribio M, Wnuk SF. Arylchlorogermanes/TBAF/"moist" toluene: a promising combination for Pd-catalyzed Germyl-Stille cross-coupling. Org Lett 2010; 12:816-9. [PMID: 20092358 DOI: 10.1021/ol9028918] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The trichlorophenyl,- dichlorodiphenyl,- and chlorotriphenylgermanes undergo Pd-catalyzed cross-couplings with aryl bromides and iodides in the presence of TBAF in toluene with addition of the measured amount of water. One chloride ligand on the Ge center allows efficient activation by fluoride to promote transfer of one, two, or three phenyl groups from the organogermane precursors.
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Affiliation(s)
- Zun-Ting Zhang
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA
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Abstract
The oxidative treatment of vinyl tris(trimethylsilyl)silanes with hydrogen peroxide in aqueous sodium hydroxide in tetrahydrofuran generates reactive silanol or siloxane species that undergo Pd-catalyzed cross-couplings with aryl, heterocyclic and alkenyl halides in the presence of Pd(PPh(3))(4) and tetrabutylammonium fluoride. Hydrogen peroxide and base are necessary for the coupling to occur while activation of the silanes with fluoride is not required. The conjugated and unconjugated tris(trimethylsilyl)silanes serve as good cross-coupling substrates. The (E)-silanes undergo coupling with retention of stereochemistry while coupling of (Z)-silanes occurred with lower stereoselectivity to produce an E/Z mixture of products.
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Affiliation(s)
- Zhizhong Wang
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA
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