17223-96-0Relevant articles and documents
Micellar Effects on the Reaction of (Arylsulfonyl)alkyl Arenesulfonates with Hydroxide Ion. 2. The Absence of Substrate Orientational Effects in a Series of Sulfonates of Different Hydrophobicities
Witte, Frank M.,Engberts, Jan B. F. N.
, p. 4130 - 4134 (1985)
Second-order rate constants for nucleophilic attack of hydroxide ion at the sulfonate sulfur atom of a series of sulfonates R1SO2CH2OSO2R2 (1a-g) in the presence of CTAB micelles (at 50 deg C) have been analyzed in terms of the pseudophase ion-exchange (PPIE) model.It is shown that the catalysis by the micelles is caused by the increased reactant concentrations in the micellar reaction volume.Large variations in the hydrophobicities of the substituents R1 and R2 (alkylaryl, alkyl) had only a minor influence on the rate constant for reaction in the micellar pseudophase (km).The same conclusion holds if the rate constants km are corrected for the different propensities of the sulfonates to respond to changes in the polarity of the reaction medium as expressed in the dielectric constant.Therefore there is no evidence that the depth of penetration and/or the orientation of the sulfonates 1a-g bound to the cetyltrimethylammonium bromide micelles is significantly affected by the hydrophobicities of R1 and R2.These findings are reconcilable with recent views cincerning the morphology of micelles.
Copper-Mediated Selenazolidine Deprotection Enables One-Pot Chemical Synthesis of Challenging Proteins
Zhao, Zhenguang,Metanis, Norman
, p. 14610 - 14614 (2019)
While chemical protein synthesis has granted access to challenging proteins, the synthesis of longer proteins is often limited by low abundance or non-strategic placement of cysteine residues, which are essential for native chemical ligations, as well as multiple purification and isolation steps. We describe the one-pot total synthesis of human thiosulfate:glutathione sulfurtransferase (TSTD1). WT-TSTD1 was synthesized in a C-to-N synthetic approach involving multiple NCL reactions, CuII-mediated deprotection of selenazolidine (Sez), and chemoselective deselenization. The seleno-analog Se-TSTD1, in which the active site Cys is replaced with selenocysteine, was also synthesized with a kinetically controlled ligation with an N-to-C synthetic approach. The catalytic activity of the two proteins indicated that Se-TSTD1 possessed only four-fold lower activity than WT-TSTD1, thus suggesting that selenoproteins can have physiologically comparable sulfutransferase activity to their cysteine counterparts.
Kinetics of the Reactions of 2,4-Dinitrophenyl Aryl Sulphides Sulphoxides and Sulphones with Hydroxide Ion in 80 percent (v/v) Ethanol-Water
Hamed, E. A.,El-Bardan, A. A.,Saad, Esmat F.,Fathalla, Magda F.
, p. 177 - 186 (2007/10/03)
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