2637-34-5Relevant articles and documents
Hydroperoxide and peroxynitrite reductase activity of poplar thioredoxin-dependent glutathione peroxidase 5: Kinetics, catalytic mechanism and oxidative inactivation
Selles, Benjamin,Hugo, Martin,Trujillo, Madia,Srivastava, Vaibhav,Wingsle, Gunnar,Jacquot, Jean-Pierre,Radi, Rafael,Rouhier, Nicolas
, p. 369 - 380 (2012)
Gpxs (glutathione peroxidases) constitute a family of peroxidases, including selenocysteine- or cysteine-containing isoforms (SeCys-Gpx or Cys-Gpx), which are regenerated by glutathione or Trxs (thioredoxins) respectively. In the present paper we show new data concerning the substrates of poplar Gpx5 and the residues involved in its catalytic mechanism. The present study establishes the capacity of this Cys-Gpx to reduce peroxynitrite with a catalytic efficiency of 106 M-1·s-1. In PtGpx5 (poplar Gpx5; Pt is Populus trichocarpa), Glu79, which replaces the glutamine residue usually found in the Gpx catalytic tetrad, is likely to be involved in substrate selectivity. Although the redox midpoint potential of the Cys44-Cys92 disulfide bond and the pKa of Cys44 are not modified in the E79Q variant, it exhibited significantly improved kinetic parameters (Kperoxide and kcat) with tert-butyl hydroperoxide. The characterization of the monomeric Y151R variant demonstrated that PtGpx5 is not an obligate homodimer. Also, we show that the conserved Phe90 is important for Trx recognition and that Trx-mediated recycling of PtGpx5 occurs via the formation of a transient disulfide bond between the Trx catalytic cysteine residue and the Gpx5 resolving cysteine residue. Finally, we demonstrate that the conformational changes observed during the transition from the reduced to the oxidized form of PtGpx5 are primarily determined by the oxidation of the peroxidatic cysteine into sulfenic acid. Also, MS analysis of in-vitro-oxidized PtGpx5 demonstrated that the peroxidatic cysteine residue can be over-oxidized into sulfinic or sulfonic acids. This suggests that some isoforms could have dual functions potentially acting as hydrogen-peroxide- and peroxynitrite- scavenging systems and/or as mediators of peroxide signalling as proposed for 2-Cys peroxiredoxins. The Authors Journal compilation
TiO2 photocatalytic reduction of bis(2-dipyridyl)disulfide to 2-mercaptopyridine by H2O: Incorporation effect of nanometer-sized Ag particles
Tada, Hiroaki,Teranishi, Kazuaki,Inubushi, Yo-Ichi,Ito, Seishiro
, p. 2345 - 2346 (1998)
A highly endothermic reduction of bis(2-dipyridyl)disulfide to 2-mercaptopyridine by H2O selectively proceeds using TiO2 as a photocatalyst, being significantly enhanced upon incorporation of nanometer-sized Ag particles on TiO2
In situ formation of protein-polymer conjugates through reversible addition fragmentation chain transfer polymerization
Liu, Jingquan,Bulmus, Volga,Herlambang, David L.,Barner-Kowollik, Christopher,Stenzel, Martina H.,Davis, Thomas P.
, p. 3099 - 3103 (2007)
(Figure Presented) A good place for rafting: Bovine serum albumin (BSA) was site-specifically modified with a reversible addition fragmentation chain transfer (RAFT) agent and used in γ-radiation-initiated polymerization of oligo(ethylene glycol) acrylate. Well-defined polymer chains were formed at the RAFT agent conjugation site of BSA leading to the generation of BSA-polymer conjugates in situ.
Reduction-sensitive tioguanine prodrug micelles
Van Der Vlies, André J.,Hasegawa, Urara,Hubbell, Jeffrey A.
, p. 2812 - 2818 (2012)
Colloidal drug and prodrug conjugates have unique targeting characteristics for tumor vasculature from the blood and for the lymphatics draining a tissue injection site. Tioguanine and tioguanine-generating prodrugs have been investigated as anticancer and immunosuppressive agents, including use in cancer immunotherapy. Recently we developed block copolymers of poly(ethylene glycol)-bl-poly(propylene sulfide) that self-assemble in aqueous solutions to form micellar structures. Since the polymers carry a free terminal thiol group resulting from the ring-opening polymerization of the propylene sulfide monomer, we sought to prepare prodrug block copolymers with tioguanine linked by a reduction-sensitive disulfide bond. The synthesis involved a disulfide exchange between the oxidized form of tioguanine and the polymer. Spectroscopic data is presented to support the proposed reaction. The polymers self-assembled when dispersed in water to form tioguanine prodrug micelles with a size range between 18 and 40 nm that released tioguanine in response to cysteine and serum as shown spectroscopically. In comparison with a poly(ethylene glycol) prodrug polymer, we show that the rate of tioguanine release can be controlled by changing the poly(propylene sulfide) block length and that the tioguanine remains bioactive with cultured cells.
Phosphodisulfide bond: A new linker for the oligonucleotide conjugation
Chassignol, Marcel,Thuong, Nguyen T.
, p. 8271 - 8274 (1998)
Oligonucleotide thiophosphates react with 2-pyridyl-disulfide derivatives to give phosphodisulfide which can, upon reduction, be easily cleaved to give the starting oligonucleotide with a terminal thiophosphate group.
Size-dependence of Fermi energy of gold nanoparticles loaded on titanium(iv) dioxide at photostationary state
Kiyonaga, Tomokazu,Fujii, Masashi,Akita, Tomoki,Kobayashi, Hisayoshi,Tada, Hiroaki
, p. 6553 - 6561 (2008)
TiO2 particle-supported Au nanoparticles (NPs) with varying sizes and good contact (Au/TiO2) were prepared under a constant loading amount by the deposition-precipitation method. The Fermi energy of Au NPs loaded on TiO2 a
A synthetic strategy using Witkop's pyrroloindole for (-)-debromoflustramine B, (+)-ent-debromoflustramine B and (+)-ent-debromoflustramide B
Cardoso, A. Sofia P.,Marques, M. Manuel B.,Srinivasan, Natarajan,Prabhakar, Sundaresan,Lobo, Ana M.
, p. 10211 - 10225 (2007)
While prenylation of (-)-Witkop's pyrroloindole (2), secured from l-tryptophan under standard N-alkylation conditions, led to a ca. 1:1 diastereoisomeric mixture of two C3a-alkylated indolenines 3 and 4, use of phase-transfer conditions altered this to ca. 1:2. Reduction followed by N-prenylation of the resulting secondary amines gave C,N-dialkylated products. The derived separable diastereoisomeric (-)- and (+)-Barton esters 19a and 19b were then converted into (-)-debromoflustramine B and (+)-ent-debromoflustramine B, respectively. A novel reaction involving oxygen and the carbanion derived from Barton ester 19b led to (+)-ent-debromoflustramide B. Treatment of N8-prenylated Witkop's pyrroloindole 5 with Lewis acid (BF3·Et2O) uncovered a new clean intramolecular cyclisation involving the prenyl unit.
Mass spectrometry-based assay for the rapid detection of thiol-containing natural products
Capehart, Stacy L.,Carlson, Erin E.
, p. 13229 - 13232 (2016)
Natural products are privileged scaffolds due to their high propensity to possess bioactivity. To expedite discovery of thiol-containing compounds, we devised a selective solid-supported reagent for their immobilization, followed by cleavage of a photocleavable linker to yield stable natural product conjugates for direct detection by mass spectrometry. Importantly, the natural products can also be tracelessly released to yield the native structures for chemical and biological evaluation.
2-Pyridinethiol/2-pyridinethione tautomeric equilibrium. A comparative experimental and computational study
Moran, Damian,Sukcharoenphon, Kengkaj,Puchta, Ralph,Schaefer III, Henry F.,Schleyer, Paul V.R.,Hoff, Carl D.
, p. 9061 - 9069 (2002)
The gas phase and solvent dependent preference of the tautomerization between 2-pyridinethiol (2SH) and 2-pyridinethione (2S) has been assessed using variable temperature Fourier transform infrared (FTIR) experiments, as well as ab initio and density functional theory computations. No spectroscopic evidence (vS-H stretch) for 2SH was observed in toluene, C6D6, heptane, or methylene chloride solutions. Although, Cs 2SH is 2.61 kcal/mol more stable than Cs 2S (CCSD(T)/cc-pVTZ//B3LYP/6-311+G(3df,2p)+ZPE), cyclohexane solvent-field relative energies (IPCM-MP2/6-311+G-(3df,2p)) favor 2S by 1.96 kcal/mol. This is in accord with the FTIR observations and in quantitative agreement with the -2.6 kcal/mol solution (toluene or C6D6) calorimetric enthalpy for the 2S/2SH tautomerization favoring the thione. As the intramolecular transition state for the 2S, 2SH tautomerization (2TS*) lies 25 (CBS-Q) to 30 kcal/mol (CCSD/cc-pVTZ) higher in energy than either tautomer, tautomerization probably occurs in the hydrogen bonded dimer. The B3LYP/6-311+G-(3df,2p) optimized C2 2SH dimer is 10.23 kcal/mol + ZPE higher in energy than the C2h 2S dimer and is only 2.95 kcal/mol + ZPE lower in energy than the C2 2TS* dimer transition state. Dimerization equilibrium measurements (FTIR, C6D6) over the temperature range 22-63°C agree: Keq298 = 165 ± 40 M-I, ΔH = -7.0 ± 0.7 kcal/mol, and ΔS = -13.4 ± 3.0 cal/(mol deg). The difference between experimental and B3LYP/6-311+G(3df,2p) [-34.62 cal/(mol deg)] entropy changes is due to solvent effects. The B3LYP/6-311+G(3df,2p) nucleus independent chemical shifts (NICS) are -8.8 and -3.5 ppm 1 A above the 2SH and 2S ring centers, respectively, and the thiol is aromatic. Although the thione is not aromatic, it is stabilized by the thioamide resonance. In solvent, the large 2S dipole, 2-3 times greater than 2SH, favors the thione tautomer and, in conclusion, 2S is thermodynamically more stable than 2SH in solution.
The effect of nanometre-sized Au particle loading on TiO2 photocatalysed reduction of bis(2-dipyridyl)disulfide to 2-mercaptopyridine by H2O
Tada,Suzuki,Yoneda,Ito,Kobayashi
, p. 1376 - 1382 (2001)
TiO2 photocatalysed reduction of bis(2-dipyridyl)disulfide (RSSR) to 2-mercaptopyridine by H2O is enhanced significantly by incorporation of nanometre-sized Au particles. The rate is strongly dependent on the amount of Au loaded (x w
