3-Substituted 4-Bromo-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-1-yloxyl Radicals as Versatile Synthons for Synthesis of New Paramagnetic Heterocycles

Kálai, Tamás; Balog, Mária; Jekő, József; Hideg, Kálmán

doi:10.1055/s-1998-2178

Cited by 34 publications

(39 citation statements)

References 22 publications

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“…Qualitative TLC was carried out on commercially prepared plates (20 × 20 × 0.02 cm) coated with Merck Kieselgel GF 254 . Compound 1 was prepared according to published procedures (Kalai et al 1998); 3-pyridineboronic acid and other reagents were purchased from Aldrich.…”

Section: Experimental Methodsmentioning

confidence: 99%

A rigid disulfide-linked nitroxide side chain simplifies the quantitative analysis of PRE data

et al. 2011

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The measurement of 1H transverse paramagnetic relaxation enhancement (PRE) has been used in biomolecular systems to determine long-range distance restraints and to visualize sparsely-populated transient states. The intrinsic flexibility of most nitroxide and metal-chelating paramagnetic spin-labels, however, complicates the quantitative interpretation of PREs due to delocalization of the paramagnetic center. Here, we present a novel, disulfide-linked nitroxide spin label, R1p, as an alternative to these flexible labels for PRE studies. When introduced at solvent-exposed α-helical positions in two model proteins, calmodulin (CaM) and T4 lysozyme (T4L), EPR measurements show that the R1p side chain exhibits dramatically reduced internal motion compared to the commonly used R1 spin label (generated by reacting cysteine with the spin labeling compound often referred to as MTSL). Further, only a single nitroxide position is necessary to account for the PREs arising from CaM S17R1p, while an ensemble comprising multiple conformations is necessary for those observed for CaM S17R1. Together, these observations suggest that the nitroxide adopts a single, fixed position when R1p is placed at solvent-exposed α-helical positions, greatly simplifying the interpretation of PRE data by removing the need to account for the intrinsic flexibility of the spin label.

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Section: Experimental Methodsmentioning

confidence: 99%

A rigid disulfide-linked nitroxide side chain simplifies the quantitative analysis of PRE data

et al. 2011

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“…Qualitative TLC was carried out on commercially available plates (20 × 20 × 0.02 cm) coated with Merck Kieselgel GF 254 . TEMPOL and all other chemicals were purchased from Aldrich, compound 2a [20], 2b [21], 2c [22], 2d [23] and KO-162 [4] was prepared as described earlier.…”

Section: Experimental Protocolsmentioning

confidence: 99%

Synthesis and study of 2-amino-7-bromofluorenes modified with nitroxides and their precursors as dual anti-amyloid and antioxidant active compounds

Kálai

Petrlová

Balog

et al. 2011

European Journal of Medicinal Chemistry

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A series of 2-aminofluorenes N-alkylated with nitroxides or their precursors were synthesized. The new compounds were tested on hydroxyl radical and peroxyl radical scavenging ability and inflammatory assay on the endothelial brain cells. In agreement with ROS scavenging ability the same compound 7-bromo-N –[(1-Oxyl-2,2,6,6-tetramethyl-1,2,3,6-tetrahydropyridine-4yl)methyl]-9H-fluoren-2-amine (3b) and its hydroxylamine salt (3b/OH/HCl) showed the anti-inflammatory property on the endothelial brain cells.

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“…[10][11][12][13][14] We found that pyrrolidine aldehyde 3 (Figure 2a)h ad been reported previously;h owever,i ts dual functionality was not exploited in spin labeling. [15] Our first aim was to establish asynthetic route that would yield reliable gram quantities of fully characterized material for subsequent studies. Tr i-bromination and Favorskii rearrangement of commercially available 4-oxo-TEMPO 1 (Figure 2a), [16] afforded the pyrrolidine nitroxide 2.T hen, acid chloride formation and subsequent reduction with sodium borohydride gave an alcohol [17] that was selectively oxidized with pyridinium dichromate to give BASL 3 in gram quantities.O wing to the paramagnetism of nitroxide radicals,NMR analysis is not possible and EPR gives little information on the molecular structure of the spin label.…”

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A Bifunctional Spin Label for Ligand Recognition on Surfaces

et al. 2017

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In situ monitoring of biomolecular recognition, especially at surfaces,s till presents as ignificant technical challenge.E lectron paramagnetic resonance (EPR) of biomolecules spin-labeled with nitroxides can offer uniquely sensitive and selective insights into these processes,b ut new spin-labeling strategies are needed. The synthesis and study of ab romoacrylaldehyde spin label (BASL), which features two attachment points with orthogonal reactivity is reported. The first examples of mannose and biotin ligands coupled to aqueous carboxy-functionalized gold nanoparticles through as pin label are presented. EPR spectra were obtained for the spin-labeled ligands both free in solution and attached to nanoparticles.T he labels were recognized by the mannosebinding lectin, Con A, and the biotin-binding protein avidinperoxidase.B inding gave quantifiable changes in the EPR spectra from which binding profiles could be obtained that reflect the strength of binding in eachc ase.

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3-Substituted 4-Bromo-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-1-yloxyl Radicals as Versatile Synthons for Synthesis of New Paramagnetic Heterocycles

Cited by 34 publications

References 22 publications

A rigid disulfide-linked nitroxide side chain simplifies the quantitative analysis of PRE data

A rigid disulfide-linked nitroxide side chain simplifies the quantitative analysis of PRE data

Synthesis and study of 2-amino-7-bromofluorenes modified with nitroxides and their precursors as dual anti-amyloid and antioxidant active compounds

A Bifunctional Spin Label for Ligand Recognition on Surfaces

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