- Reactivity and selectivity of the reaction of: O, O -diethyl 2,4-dinitrophenyl phosphate and thionophosphate with thiols of low molecular weight
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A reactivity and selectivity study of O,O-diethyl 2,4-dinitrophenyl phosphate (1) and O,O-diethyl 2,4-dinitrophenyl thionophosphate (2) with a series of thiols of low molecular weight: N-acetyl cysteine (NAC), l-cysteine (Cys), homocysteine (Hcys), glutathione (GSH), and d-penicillamine (Pen) was conducted. Results show that (i) these nucleophiles only attack at the aromatic moiety of both triester derivatives, (ii) a kinetic control product by sulfhydryl attack of thiols was observed in the reactions of both triesters with Cys and Hcys, followed by an intramolecular amine attack leading to a thermodynamic control product. The kinetic study leads to the proposal of Meisenheimer complex formation and then proton transfer to the reaction media as the mechanism of these reactions.
- Santos,Aliaga,Alarcón,Torres,Céspedes,Pavez
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supporting information
p. 6479 - 6486
(2016/07/16)
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- Mercapturic acids (N-acetylcysteine S-conjugates) as endogenous substrates for the renal organic anion transporter-1
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Mercapturic acids are N-acetyl-L-cysteine S-conjugates that are formed from a range of endogenous and exogenous chemicals. Although the kidney is a major site for elimination of mercapturic acids, the transport mechanisms involved have not been identified. The present study examined whether mercapturic acids are substrates for the renal basolateral organic anion transporter-1 (Oat1) from rat kidney. This carrier mediates uptake of organic anions from the bloodstream in exchange for intracellular α-ketoglutarate. Uptake of [3H]p-aminohippuric acid (PAH) in Oat1-expressing Xenopus laevis oocytes was strongly inhibited by S-(2,4-dinitrophenyl)-N-acetyl-L-cysteine (DNP-NAC) and by all other mercapturic acids tested, including the endogenous mercapturic acid N-acetyl-leukotriene E4. Inhibition by the mercapturic acids was competitive, which is consistent with the hypothesis that these compounds are substrates for Oat1. This conclusion was supported by the direct demonstration of saturable [35S]DNP-NAC uptake in Oat1-expressing oocytes. [35S]DNP-NAC uptake was inhibited by PAH and other mercapturic acids and was stimulated in oocytes preloaded with glutarate. The apparent Km value for DNP-NAC uptake was only 2 μM, indicating that this mercapturic acid is a high affinity substrate for Oat1. Together, these data indicate that clearance of endogenous mercapturic acids is an important function of the renal organic anion transporter.
- Pombrio, James M.,Giangreco, Adam,Li, Liqiong,Wempe, Michael F.,Anders,Sweet, Douglas H.,Pritchard, John B.,Ballatori, Nazzareno
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p. 1091 - 1099
(2008/01/27)
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- 1,2,4-TRINITROBENZENE AS A THIOL REAGENT
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The 2,4-dinitrophenylation of thiol or amino group with 1,2,4-trinitrobenzene proceeded quantitatively at pH 8.5 and 30 deg C.The rate of S-dinitrophenylation was ca. 1E4 times faster than that of N-dinitrophenylation.So this reaction can be used for both the determination of thiol even in the presence of large excess amine and the specific modification of thiol in proteins.
- Takahashi, Seitaro,Kokubo, Masayuki,Satake, Kazuo
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p. 1445 - 1448
(2007/10/02)
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