The paramagnetism of a lanthanoid tag site-specifically installed on a protein provides a rich source of structural information accessible by
nuclear magnetic resonance (NMR) and electron ...paramagnetic resonance (EPR) spectroscopy. Here we report a lanthanoid tag for selective reaction
with cysteine or selenocysteine with formation of a (seleno)thioether bond and a short tether between the lanthanoid ion and the protein backbone. The tag
is assembled on the protein in three steps, comprising (i) reaction with 4-fluoro-2,6-dicyanopyridine (FDCP); (ii) reaction of the cyano groups with
α-cysteine, penicillamine or β-cysteine to complete the lanthanoid chelating moiety; and (iii) titration with a lanthanoid ion. FDCP
reacts much faster with selenocysteine than cysteine, opening a route for selective tagging in the presence of solvent-exposed cysteine residues.
Loaded with Tb3+ and Tm3+ ions, pseudocontact shifts were observed in protein NMR spectra, confirming that the tag delivers good
immobilisation of the lanthanoid ion relative to the protein, which was also manifested in residual dipolar couplings. Completion of the tag with
different 1,2-aminothiol compounds resulted in different magnetic susceptibility tensors. In addition, the tag proved suitable for measuring
distance distributions in double electron–electron resonance experiments after titration with Gd3+ ions.
The metallo-β-lactamase IMP-1 features a flexible loop near the active site that assumes different conformations in single crystal structures, which may assist in substrate binding and enzymatic ...activity. To probe the position of this loop, we labelled the tryptophan residues of IMP-1 with 7-13C-indole and the protein with lanthanoid tags at three different sites. The magnetic susceptibility anisotropy (Δχ) tensors were determined by measuring pseudocontact shifts (PCSs) of backbone amide protons. The Δχ tensors were subsequently used to identify the atomic coordinates of the tryptophan side chains in the protein. The PCSs were sufficient to determine the location of Trp28, which is in the active site loop targeted by our experiments, with high accuracy. Its average atomic coordinates showed barely significant changes in response to the inhibitor captopril. It was found that localisation spaces could be defined with better accuracy by including only the PCSs of a single paramagnetic lanthanoid ion for each tag and tagging site. The effect was attributed to the shallow angle with which PCS isosurfaces tend to intersect if generated by tags and tagging sites that are identical except for the paramagnetic lanthanoid ion.
Sintezeta rinda "push-pull" tipa organisko stiklu. Iegutie savienojumi, 3-{4-bis(2-tritiloksietil)aminofenil}-2-{4-(4-acetilfenil)diazenilfenil}- akrilnitrils, ...3-{4-bis(2-tritiloksietil)aminofenil}-2-{4-(4-nitrofenil)- diazenil-fenil}akrilnitrils, 3-{4-bis(2-tritiloksietil)aminofenil}-2-{4-(2-brom-4-nitrofenil)diazenilfenil} akrilnitrils, {4-{4-2-(bis(2-tritiloksietil)aminofenil)-1-cianovinilfenil}diazenil benziliden} malonnitrils, 3-{4-bis(2-tritil-oksietil)aminofenil}-2-{4-(2-ciano-4-nitrofenil)diazenilfenil} akrilnitrils un 3-{4-(bis(2-(trifenilsililoksi) etil)amino)fenil)-2-(4-((2-brom-4-nitrofenil)diazeni)-fenil}-akrilonitrils, raksturojas ar intensivu elektronu absorbciju gaismas spektra redzamaja dala un tie no viegli gaistosiem skidinatajiem (hloroforms vai metilenhlorids) spej veidot planas amorfas kartinas.
Sintezeta rinda "push-pull" tipa organisko stiklu. Iegutie savienojumi, 3-{4-bis(2-tritiloksietil)aminofenil}-2-{4-(4-acetilfenil)diazen i lfenil}- akrilnitrils, ...3-{4-bis(2-tritiloksietil)aminofenil}-2-{4-(4-nitrofenil)- diazenil-fenil}akrilnitrils, 3-{4-bis(2-tritiloksietil)aminofenil}-2-{4-(2-brom-4-nitrofenil) d iazenilfenil} akrilnitrils, {4-{4-2-(bis(2-tritiloksietil)aminofenil)-1-cianovinilfenil}dia z enil benziliden} malonnitrils, 3-{4-bis(2-tritil-oksietil)aminofenil}-2-{4-(2-ciano-4-nitrofeni l )diazenilfenil} akrilnitrils un 3-{4-(bis(2-(trifenilsililoksi) etil)amino)fenil)-2-(4-((2-brom-4-nitrofenil)diazeni)-fenil}-akril o nitrils, raksturojas ar intensivu elektronu absorbciju gaismas spektra redzamaja dala un tie no viegli gaistosiem skidinatajiem (hloroforms vai metilenhlorids) spej veidot planas amorfas kartinas.
Dotaja raksta eksperimentali petita trans-cis fotoizomerizacijas iespejama loma virsmas reljefa rezgu ieraksta stilbena azobenzola atvasinajumos, kad ieraksts un nolase tika veikti ar sarkano 633 nm ...gaismu. Konstatets , ka materiala relaksacijai ir stingra nemonotona ietekme uz holografiska ieraksta efektivitati un ka ierakstas ne vien virsmas reljefa rezgi, ber ari tilpuma rezgi. Iegutie rezultati nelauj secinat, ka trans-cis fotoizomerizacijas spele galveno lomu. Izdarits secinajums, ka hromoforu fotodegradacija un fotoorientacija ir galvenie ieraksta mehanismi petitajos materiaos.
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