46147-14-2Relevant articles and documents
Room-temperature electron spin relaxation of nitroxides immobilized in trehalose: Effect of substituents adjacent to NO-group
Kuzhelev, Andrey A.,Strizhakov, Rodion K.,Krumkacheva, Olesya A.,Polienko, Yuliya F.,Morozov, Denis A.,Shevelev, Georgiy Yu.,Pyshnyi, Dmitrii V.,Kirilyuk, Igor A.,Fedin, Matvey V.,Bagryanskaya, Elena G.
, p. 1 - 7 (2016/03/22)
Trehalose has been recently promoted as efficient immobilizer of biomolecules for room-temperature EPR studies, including distance measurements between attached nitroxide spin labels. Generally, the structure of nitroxide influences the electron spin relaxation times, being crucial parameters for room-temperature pulse EPR measurements. Therefore, in this work we investigated a series of nitroxides with different substituents adjacent to NO-moiety including spirocyclohexane, spirocyclopentane, tetraethyl and tetramethyl groups. Electron spin relaxation times (T1, Tm) of these radicals immobilized in trehalose were measured at room temperature at X- and Q-bands (9/34 GHz). In addition, a comparison was made with the corresponding relaxation times in nitroxide-labeled DNA immobilized in trehalose. In all cases phase memory times Tm were close to 700 ns and did not essentially depend on structure of substituents. Comparison of temperature dependences of Tm at T = 80-300 K shows that the benefit of spirocyclohexane substituents well-known at medium temperatures (～100-180 K) becomes negligible at 300 K. Therefore, unless there are specific interactions between spin labels and biomolecules, the room-temperature value of Tm in trehalose is weakly dependent on the structure of substituents adjacent to NO-moiety of nitroxide. The issues of specific interactions and stability of nitroxide labels in biological media might be more important for room temperature pulsed dipolar EPR than differences in intrinsic spin relaxation of radicals.
Synthesis, resolution and assignment of absolute configuration of trans 3-amino-1-oxyl-2,2,5,5-tetramethylpyrrolidine-4-carboxylic acid (POAC), a cyclic, spin-labelled β-amino acid
Wright, Karen,Dutot, Laurence,Wakselman, Michel,Mazaleyrat, Jean-Paul,Crisma, Marco,Formaggio, Fernando,Toniolo, Claudio
, p. 4416 - 4426 (2008/09/20)
Racemic trans 3-(9-fluorenylmethyloxycarbonylamino)-1-oxyl-2,2,5,5-tetramethylpyrrolid ine-4-carboxylic acid (Fmoc-POAC-OH), prepared by conventional methods, was resolved upon esterification with (aR)-2,2′-dihydroxy-1,1′-binaphthyl. Separation of the obtained diastereomeric monoesters Fmoc-(±)-trans-POAC-O-(aR)-binaphthol by crystallization/chromatography, and removal of the chiral auxiliary by saponification of the aryl ester function furnished both enantiomers (+)-(3R,4R)-Fmoc-POAC-OH and (-)-(3S,4S)-Fmoc-POAC-OH. The absolute configuration of the asymmetric C3, C4 carbons of POAC were assigned from the induced circular dichroism of a flexible biphenyl probe present in the terminally protected dipeptide derivatives Boc-Bip-(+)-POAC-OMe and Boc-Bip-(-)-POAC-OMe (Bip, 2′,1′:1,2;1″,2″:3,4-dibenzcyclohepta-1,3-diene-6 -amino-6-carboxylic acid). This assignment was confirmed by X-ray diffraction analysis of the diastereomeric monoester Fmoc-(+)-trans-POAC-O-(aR)-binaphthol, shown to be (aR,3R,4R). Solution synthesis of peptides to the hexamer level, based on the (3R,4R)-POAC enantiomer combined with (1S,2S)-2-aminocyclopentane-1-carboxylic acid, was carried out to examine coupling conditions at both C- and N-termini of the POAC residue, in view of further syntheses and 3D-structural investigations.
Synthesis and enzyme-catalyzed hydrolysis of a radical-masked glycosylated spin-label reagent
Sato, Shingo,Nemoto, Miho,Kumazawa, Toshihiro,Matsuba, Shigeru,Onodera, Jun-Ichi,Aoyama, Masaaki,Obara, Heitaro,Kamada, Hitoshi
, p. 2425 - 2432 (2007/10/03)
N1-Acetoxy-2,2,6,6-tetramethylpiperidin-4-yl 2,3,4,6-tetra-O-benzyl-α- and -β-d-glucopyranosides (3-α, β) and N1-acetoxy-2,2,5,5-tetramethylpyrrolin-3-oyl 2,3,4,6-tetra-O-benzyl-α- and -β-d-glucopyranosylamines (9-α, β) were synthesized in good yield by Schmidt's glycosylation method. Their subsequent O-debenzylation was proceeded successfully to give the desired products 1-α, and 1-β in good yield, and 2-α in a low yield, without 2-β by only short-timed hydrogenolysis in the presence of palladium-on-carbon (Pd-C) in a CHCl3-MeOH solvent system that included concentrated HCl. Upon enzyme-catalyzed hydrolysis, only 2-α was hydrolyzed by the esterase, while both of 1-α and 1-β were not hydrolyzed by any other enzyme such as lipase. These 2-α can likely be used as a new water-soluble radical-masked glycosylated spin-label reagent.
