The Experts below are selected from a list of 233973 Experts worldwide ranked by ideXlab platform
D. James Morré - One of the best experts on this subject based on the ideXlab platform.
-
The Sulfonylurea-Inhibited NADH Oxidase Activity of HeLa Cell Plasma Membranes has Properties of a Protein Disulfide–Thiol Oxidoreductase with Protein Disulfide–Thiol Interchange Activity
Journal of Bioenergetics and Biomembranes, 1998Co-Authors: Pin-ju Chueh, Juliana Lawler, D. James MorréAbstract:Plasma membrane vesicles of HeLa cells are characterized by a drug-responsive oxidation of NADH. The NADH oxidation takes place in an argon or nitrogen atmosphere and in samples purged of oxygen. Direct assay of protein Thiols by reaction with 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB; Ellman's reagent), suggests that protein disulfides may be the natural electron acceptors for NADH oxidation by the plasma membrane vesicles. In the presence of NADH, protein disulfides of the membranes were reduced with a concomitant stoichiometric increase in protein Thiols. The increase in protein Thiols was inhibited in parallel to the inhibition of NADH oxidation by the antitumor sulfonylurea LY181984 with an EC_50 of ca. 30 nM. LY181984, with an EC_50 of 30 nM, also inhibited a protein disulfide–thiol interchange activity based on the restoration of activity to inactive (scrambled) RNase and thiol oxidation. The findings suggest that thiol oxidation, NADH-dependent disulfide reduction (NADH oxidation), and protein disulfide–thiol interchange in the absence of NADH all may be manifestations of the same sulfonylurea binding protein of the HeLa plasma membrane. A surface location of the Thiols involved was demonstrated using detergents and the impermeant thiol reagent p -chloromercuriphenylsulfonic acid (PCMPS). The surface location precludes a physiological role of the protein in NADH oxidation. Rather, it may carry out some other role more closely related to a function in growth, such as protein disulfide–thiol interchange coupled to cell enlargement.
Bart Jan Ravoo - One of the best experts on this subject based on the ideXlab platform.
-
Photochemical Microcontact Printing by Thiol−Ene and Thiol−Yne Click Chemistry
Langmuir, 2010Co-Authors: Christian Wendeln, Stefan Rinnen, Heinrich F. Arlinghaus, Christian Schulz, Bart Jan RavooAbstract:This article describes the microstructured immobilization of functional Thiols on alkene- and alkyne-terminated self-assembled monolayers on silicon oxide substrates by photochemical microcontact printing. A photochemical thiol−ene or thiol−yne “click” reaction was locally induced in the area of contact between stamp and substrate by irradiation with UV light (365 nm). The immobilization reaction by photochemical microcontact printing was verified by contact angle measurements, X-ray photoelectron spectroscopy, atomic force microscopy, and time-of-flight secondary ion mass spectrometry. The reaction rate of photochemical microcontact printing by thiol−ene chemistry was studied using time dependent contact angle measurements. The selective binding of lectins to galactoside microarrays prepared by photochemical microcontact printing was also demonstrated. It was found that photochemical microcontact printing results in a high surface coverage of functional Thiols within 30 s of printing even for dilute (mM)...
-
photochemical microcontact printing by thiol ene and thiol yne click chemistry
Langmuir, 2010Co-Authors: Christian Wendeln, Stefan Rinnen, Heinrich F. Arlinghaus, Christian Schulz, Bart Jan RavooAbstract:This article describes the microstructured immobilization of functional Thiols on alkene- and alkyne-terminated self-assembled monolayers on silicon oxide substrates by photochemical microcontact printing. A photochemical thiol−ene or thiol−yne “click” reaction was locally induced in the area of contact between stamp and substrate by irradiation with UV light (365 nm). The immobilization reaction by photochemical microcontact printing was verified by contact angle measurements, X-ray photoelectron spectroscopy, atomic force microscopy, and time-of-flight secondary ion mass spectrometry. The reaction rate of photochemical microcontact printing by thiol−ene chemistry was studied using time dependent contact angle measurements. The selective binding of lectins to galactoside microarrays prepared by photochemical microcontact printing was also demonstrated. It was found that photochemical microcontact printing results in a high surface coverage of functional Thiols within 30 s of printing even for dilute (mM)...
Kristine A Nolin - One of the best experts on this subject based on the ideXlab platform.
-
conjugate addition of unactivated Thiols to α β unsaturated ketones catalyzed by a bifunctional rhenium v oxo complex
Tetrahedron Letters, 2012Co-Authors: Allan Peng, Ross Rosenblatt, Kristine A NolinAbstract:Abstract ReOCl3(OPPh3)(S(CH3)2) has been found to be an efficient bifunctional catalyst for the 1,4-addition of Thiols to α,β-unsaturated ketones. The addition of thiophenol derivatives and alkyl Thiols proceeds under mild reaction conditions without pre-activation of the thiol or exogenous base. Reactions of aryl, alkyl, and cyclic enones produce the corresponding β-sulfanyl ketones in good to excellent yield.
Lena Q - One of the best experts on this subject based on the ideXlab platform.
-
thiol synthesis and arsenic hyperaccumulation in pteris vittata chinese brake fern
Environmental Pollution, 2004Co-Authors: Weihua Zhang, Kelsey R Downum, Lena QAbstract:Abstract Pteris vittata (Chinese brake fern) has potential for phytoremediation of As-contaminated sites. In this study, the synthesis of total Thiols and acid-soluble Thiols in P. vittata was investigated under arsenic exposure. The strong and positive correlation between As concentration and acid-soluble Thiols in plant leaflets suggests that acid-soluble Thiols may play a role in As detoxification. A major As-induced thiol was purified and characterized. A molecular ion (M+1) of 540 m / z suggests that the thiol was a phytochelatin (PC) with two base units (PC 2 ). However, the ratios of acid-soluble Thiols to As in leaflets exposed to As ranged from 0.012 to 0.026, suggesting that only a very small part of As is complexed by PC 2 . PCs could play a minor detoxification role in this hyperaccumulator. A PC-independent mechanism appears to be mainly involved in As tolerance, while PC-dependent detoxification seems to be a supplement.
-
low molecular weight Thiols in arsenic hyperaccumulator pteris vittata upon exposure to arsenic and other trace elements
Environmental Pollution, 2004Co-Authors: Jinhui Su, Lena QAbstract:Low molecular weight thiol-containing compounds have been reported to play an important role in metal detoxification and accumulation in some higher plants. The formation of these low molecular weight Thiols in the recently discovered arsenic hyperaccumulator, Chinese Brake fern (Pteris vittata) upon exposure to arsenic and other trace metals was investigated. In addition to cysteine and glutathione, an unidentified thiol was observed in the plants exposed to arsenic, which was not found in the control. The concentration of the unidentified thiol showed a very strong and positive correlation with arsenic concentration in the leaflets. The unidentified thiol was low in rachises and undetectable in the roots for As-treated plants. Total and acid-soluble Thiols were also measured and the results indicated that arsenic mainly stimulated the synthesis of acid-soluble thiol in Chinese Brake. The investigations of other trace elements (Cd, Cu, Cr, Zn, Pb, Hg, and Se) showed that these elements were not accumulated in Chinese Brake to high levels and the synthesis of the unidentified thiol in the plant was not observed. Our study suggests that the unidentified thiol was induced specifically by arsenic and the distribution patterns of the unidentified thiol and arsenic in the plant were consistent, indicating that the synthesis of this compound was related to As exposure.
Christian Wendeln - One of the best experts on this subject based on the ideXlab platform.
-
Photochemical Microcontact Printing by Thiol−Ene and Thiol−Yne Click Chemistry
Langmuir, 2010Co-Authors: Christian Wendeln, Stefan Rinnen, Heinrich F. Arlinghaus, Christian Schulz, Bart Jan RavooAbstract:This article describes the microstructured immobilization of functional Thiols on alkene- and alkyne-terminated self-assembled monolayers on silicon oxide substrates by photochemical microcontact printing. A photochemical thiol−ene or thiol−yne “click” reaction was locally induced in the area of contact between stamp and substrate by irradiation with UV light (365 nm). The immobilization reaction by photochemical microcontact printing was verified by contact angle measurements, X-ray photoelectron spectroscopy, atomic force microscopy, and time-of-flight secondary ion mass spectrometry. The reaction rate of photochemical microcontact printing by thiol−ene chemistry was studied using time dependent contact angle measurements. The selective binding of lectins to galactoside microarrays prepared by photochemical microcontact printing was also demonstrated. It was found that photochemical microcontact printing results in a high surface coverage of functional Thiols within 30 s of printing even for dilute (mM)...
-
photochemical microcontact printing by thiol ene and thiol yne click chemistry
Langmuir, 2010Co-Authors: Christian Wendeln, Stefan Rinnen, Heinrich F. Arlinghaus, Christian Schulz, Bart Jan RavooAbstract:This article describes the microstructured immobilization of functional Thiols on alkene- and alkyne-terminated self-assembled monolayers on silicon oxide substrates by photochemical microcontact printing. A photochemical thiol−ene or thiol−yne “click” reaction was locally induced in the area of contact between stamp and substrate by irradiation with UV light (365 nm). The immobilization reaction by photochemical microcontact printing was verified by contact angle measurements, X-ray photoelectron spectroscopy, atomic force microscopy, and time-of-flight secondary ion mass spectrometry. The reaction rate of photochemical microcontact printing by thiol−ene chemistry was studied using time dependent contact angle measurements. The selective binding of lectins to galactoside microarrays prepared by photochemical microcontact printing was also demonstrated. It was found that photochemical microcontact printing results in a high surface coverage of functional Thiols within 30 s of printing even for dilute (mM)...
