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61.
Piedad del Socorro Murdoch Nicole A. Kratochwil John A. Parkinson Marina Patriarca Peter J. Sadler 《Angewandte Chemie (International ed. in English)》1999,38(19):2949-2951
Both oxidized and reduced glutathione (γ-L -Glu-L -Cys-Gly) react with the anticancer complex [Pt(en)Cl2] to form the bicyclic complex illustrated (en=ethylenediamine). This unprecedented structure, which was determined from extensive NMR experiments, contains a ten-membered macrochelate ring. 相似文献
62.
Manas Kumar Pradhan Surya Suresh Puthenpurackal Aasheesh Srivastava 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(2):e202314960
Herein, we report a novel enzymatic dimerization-induced self-assembly (e-DISA) procedure that converts alanine-tyramine conjugates into highly uniform enzyme-loaded nanoparticles (NPs) or nanocontainers by the action of horseradish peroxidase (HRP) in an aqueous medium under ambient conditions. The NP formation was possible with both enantiomers of alanine, and the average diameter could be varied from 150 nm to 250 nm (with a 5–12 % standard deviation of as-prepared samples) depending on the precursor concentration. About 60 % of the added HRP enzyme was entrapped within the NPs and was subsequently utilized for post-synthetic modification of the NPs with phenolic compounds such as tyramine or tannic acid. One-pot multi-enzyme entrapment of glucose oxidase (GOx) and peroxidase (HRP) within the NPs was also achieved. These GOx-HRP loaded NPs allowed multimodal detection of glucose, including that present in human saliva, with a limit of detection (LoD) of 740 nM through fluorimetry. The NPs exhibited good cytocompatibility and were stable to changes in pH (acidic to basic), temperature, ultrasonication, and even the presence of organic solvent (EtOH) to a certain extent, since they are stabilized by intermolecular hydrogen bonding, π-π, and CH-π interactions. The proposed e-DISA procedure can be widely expanded through the design of diverse enzyme-responsive precursors. 相似文献
63.
64.
Xing L Kurumbail RG Frazier RB Davies MS Fujiwara H Weinberg RA Gierse JK Caspers N Carter JS McDonald JJ Moore WM Vazquez ML 《Journal of computer-aided molecular design》2009,23(1):13-24
Inducible, microsomal prostaglandin E synthase 1 (mPGES-1), the terminal enzyme in the prostaglandin (PG) biosynthetic pathway,
constitutes a promising therapeutic target for the development of new anti-inflammatory drugs. To elucidate structure–function
relationships and to enable structure-based design, an mPGES-1 homology model was developed using the three-dimensional structure
of the closest homologue of the MAPEG family (Membrane Associated Proteins in Eicosanoid and Glutathione metabolism), mGST-1.
The ensuing model of mPGES-1 is a homo-trimer, with each monomer consisting of four membrane-spanning segments. Extensive
structure refinement revealed an inter-monomer salt bridge (K26-E77) as well as inter-helical interactions within each monomer,
including polar hydrogen bonds (e.g. T78-R110-T129) and hydrophobic π-stacking (F82-F103-F106), all contributing to the overall
stability of the homo-trimer of mPGES-1. Catalytic co-factor glutathione (GSH) was docked into the mPGES-1 model by flexible
optimization of both the ligand and the protein conformations, starting from the initial location ascertained from the mGST-1
structure. Possible binding site for the substrate, prostaglandin H2 (PGH2), was identified by systematically probing the refined molecular structure of mPGES-1. A binding model was generated by induced
fit docking of PGH2 in the presence of GSH. The homology model prescribes three potential inhibitor binding sites per mPGES-1 trimer. This was
further confirmed experimentally by equilibrium dialysis study which generated a binding stoichiometric ratio of approximately
three inhibitor molecules to three mPGES-1 monomers. The structural model that we have derived could serve as a useful tool
for structure-guided design of inhibitors for this emergently important therapeutic target. 相似文献
65.
A rapid method using capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was developed to determine free and protein-bound glutathione (GSH) in human HepG2 hepatocarcinoma cells. The samples were derivatized with 5-iodoacetamidofluorescein (5-IAF), and analyzed at 22 kV using sodium phosphate buffer (10mM, pH 11.4) and an uncoated 58 cm x 75 microm I.D. fused silica capillary. The analysis time was less than 10 min and N-acetylcysteine was used as internal standard. The derivatization conditions, such as reaction time, 5-IAF concentration, running buffer and cartridge temperature were optimized. Argon gas was used in the study to prevent the oxidization of GSH during sample preparation. The optimized method required only 30-40 nl sample per analysis and was fast and sensitive. The method was applied to the analyses of HepG2 cells treated with the small metal chelating agent, pyrrolidine dithiocarbamate (PDTC). The results demonstrate that the amount of protein-bound GSH, which reflects the amount of protein S-glutathionylation, increased in a time-dependent manner upon cell treatment with PDTC, reaching a maximum of over 50% increase 2h post-PDTC. 相似文献
66.
The peroxidase activities of the complexes of hemin and intermolecular four-stranded G-quadruplexes formed by short-stranded XnGmXp sequences (X = A, T or C), especially TnGmTp sequences, were compared. The results, combining with those of circular dichroism (CD) spectra and acid-base transition study for DNA-hemin complexes, provide some important information about DNAzymes based on G-quadruplex-hemin complexes, such as the formation of a G-quadruplex structure is an important factor for determining whether a DNA sequence can enhance the catalytic activity of hemin; both intramolecular parallel G-quadruplexes and intermolecular four-stranded parallel G-quadruplexes can enhance the catalytic activity of hemin; the addition of T nucleotides to the 5′-end of a G-tract confers corresponding G-quadruplex greatly enhanced catalytic activity, whereas the addition of T nucleotides to the 3′-end of the G-tract has little effect; the high catalytic activity of hemin in the presence of some short-stranded G-rich sequences may be a result of the reduction of the acidity of the bound hemin cofactor. These studies provide more information for the DNA-hemin peroxidase model system, may help to elucidate the structure-function relationship of peroxidase enzymes and to develop novel, highly efficient peroxidase-liking DNAzymes. As a sequence of such an investigation, a new Hg2+ detection method was developed. 相似文献
67.
A rapid non-separative spectroflourimetric method based on the second-order calibration of the excitation-emission data matrix was proposed for the determination of glutathione (GSH) in human plasma. In the phosphate buffer solution of pH 8.0 GSH reacts with ortho-phthaldehyde (OPA) to yield a fluorescent adduct with maximum fluorescence intensity at about 420 nm. To handle the interfering effects of the OPA adducts with aminothiols other than GSH in plasma as well as intrinsic fluorescence of human plasma, parallel factor (PARAFAC) analysis as an efficient three-way calibration method was employed. In addition, to model the indirect interfering effect of the plasma matrix, PARAFAC was coupled with standard addition method. The two-component PARAFAC modeling of the excitation-emission matrix fluorescence spectra accurately resolved the excitation and emission spectra of GSH, plasma (or plasma constituents). The concentration-related PARAFAC score of GSH represented a linear correlation with the concentration of added GSH, similar to that is obtained in simple standard addition method. Using this standard addition curve, the GSH level in plasma was found to be 6.10 ± 1.37 μmol L−1. The accuracy of the method was investigated by analysis of the plasma samples spiked with 1.0 μmol L−1 of GSH and a recovery of 97.5% was obtained. 相似文献
68.
Glutathione (GSH) tagged with a ferrocene (Fc) label at its C‐terminal was synthesized via coupling ferrocenyl amine to glutathione using o‐(benzotriazol‐1‐yl)‐N,N,N′,N′‐tetramethyluronium (HBTU)/1‐hydroxybenzotrizole (HOBt). The presence of Fc yielded well defined voltammetric signals, rendering the Fc‐tagged GSH (GSH‐Fc) suitable for electrochemical studies of GSH binding to other biological species. The interaction of GSH‐Fc with bovine serum albumin (BSA) was investigated, and a binding ratio of 1.41±0.06 (GSH‐Fc/BSA) and an affinity constant Ka of 6.53±2.01×106 M?1 were determined. These results compare well with those measured by fluorescence using untagged GSH, suggesting that the attachment of Fc to GSH does not significantly perturb the GSH structure and binding behavior. By contrasting the binding behavior to several compounds that are known to conjugate to different domains of BSA, the voltammetric study confirmed that GSH‐Fc binds at subdomain IIA of BSA with high affinity. The versatility of GSH‐Fc for studying GSH binding to surface‐confined proteins was also demonstrated with the GSH binding to electroinactive Zn‐metallothionein (Zn7‐MT) through hydrogen binding at the region between the Zn7‐MT α and β domains. 相似文献
69.
Voltammetric sensor for glutathione determination based on ferrocene-modified carbon paste electrode
Jahan Bakhsh Raoof Reza Ojani Mansureh Kolbadinezhad 《Journal of Solid State Electrochemistry》2009,13(9):1411-1416
The electrocatalytic oxidation of glutathione (GSH) has been studied at the surface of ferrocene-modified carbon paste electrode
(FMCPE). Cyclic voltammetry (CV), double potential step chronoamperometry, and differential pulse voltammetry (DPV) techniques
were used to investigate the suitability of incorporation of ferrocene into FMCPE as a mediator for the electrocatalytic oxidation
of GSH in buffered aqueous solution. Results showed that pH 7.00 is the most suitable for this purpose. In the optimum condition
(pH 7.00), the electrocatalytic ability of about 480 mV can be found and the heterogeneous rate constant of catalytic reaction
was calculated as . Also, the diffusion coefficient of glutathione, D, was found to be 3.61 × 10–5 cm2 s−1. The electrocatalytic oxidation peak current of glutathione at the surface of this modified electrode was linearly dependent
on the GSH concentration and the linear analytical curves were obtained in the ranges of 3.2 × 10–5 M–1.6 × 10–3 M and 2.2 × 10–6 M–3.5 × 10–3 M with cyclic voltammetry and differential pulse voltammetry methods, respectively. The detection limits (3σ) were determined as 1.8 × 10–5 M and 2.1 × 10–6 M using CV and DPV, respectively. Finally, the electrocatalytic oxidation of GSH at the surface of this modified electrode
can be employed as a new method for the voltammetric determination of glutathione in real samples such as human plasma. 相似文献
70.
Enzymatic rotating biosensor for cysteine and glutathione determination in a FIA system 总被引:1,自引:0,他引:1
The high sensitivity that can be attained using an enzymatic system and mediated by catechols has been verified by on-line interfacing of a rotating biosensor and continuous flow/stopped-flow/continuous-flow processing. Horseradish peroxidase, HRP, [EC 1.11.1.7], immobilized on a rotating disk, in presence of hydrogen peroxide catalyzed the oxidation of catechols, whose back electrochemical reduction was detected on glassy carbon electrode surface at −150 mV. Thus, when l-cysteine (Cys) or glutathione (GSH) was added to the solution, these thiol-containing compounds participate in Michael addition reactions with catechols to form the corresponding thioquinone derivatives, decreasing the peak current obtained proportionally to the increase of its concentration. Cys was used as the model thiol-containing compound for the study. The highest response for Cys was obtained around pH 7. This method could be used to determine Cys concentration in the range 0.05-90 μM (r = 0.998) and GSH concentration in the range 0.04-90 μM (r = 0.999). The determination of Cys and GSH were possible with a limit of detection of 0.7 and 0.3 nM, respectively, in the processing of as many as 25 samples per hour. Current response of the HRP-rotating biosensor is not affected by the oxidized form of GSH and Cys (glutathione disulfide, GSSG, and l-cystine, respectively), by sulfur-containing and alkyl-amino compounds such as methionine and lysine, respectively. The interferences from easily oxidizable species such as ascorbic acid and uric acid are lowest. 相似文献