51-85-4Relevant articles and documents
Oxyhalogen-sulfur chemistry - Kinetics and mechanism of the oxidation of cysteamine by acidic iodate and iodine
Chanakira, Alice,Chikwana, Edward,Peyton, David H.,Simoyi, Reuben H.
, p. 49 - 57 (2006)
The oxidation of cysteamine by iodate and aqueous iodine has been studied in neutral to mildly acidic conditions. The reaction is relatively slow and is heavily dependent on acid concentration. The reaction dynamics are complex and display clock behavior, transient iodine production, and even oligooscillatory production of iodine, depending upon initial conditions. The oxidation product was the cysteamine dimer (cystamine), with no further oxidation observed past this product. The stoichiometry of the reaction was deduced to be IO 3- + 6H2NCH2CH2SH → I- + 3H2NCH2CH2S-SCH 2CH2NH2 + 3H2O in excess cysteamine conditions, whereas in excess iodate the stoichiometry of the reaction is 2IO3- + 10H2NCH2CH2SH → I2 + 5H2NCH2CH2S-SCH 2CH2NH2 + 6H2O. The stoichiometry of the oxidation of cysteamine by aqueous iodine was deduced to be I2 + 2H2NCH2CH2SH → 2I- + H 2NCH2CH2S-SCH2CH2NH 2 + 2H+. The bimolecular rate constant for the oxidation of cysteamine by iodine was experimentally evaluated as 2.7 (mol L -1)-1 s-1. The whole reaction scheme was satisfactorily modeled by a network of 14 elementary reactions.
Oxidation of aminothiols by molecular oxygen catalyzed by copper ions. Stoichiometry of the reaction
Bagiyan,Koroleva,Soroka,Ufimtsev
, p. 1129 - 1134 (2003)
Catalysis of oxidation of aminothiols by copper ions was studied depending on the structure of aminothiols and pH of the medium. The catalytic reaction proceeds in the inner coordination sphere of Cu+. At pH 7-9, oxidation of bidentate aminothiols involves reduction of O2 to H 2O2. At pH 9-13, oxidation of chelating aminothiols is accompanied by reduction of O2 to H2O, whereas oxidation of weak-chelating aminothiols still proceeds by the former mechanism. In this process, the thiolate anions coordinated to the Cu+ ions lose one electron each and are oxidized to amino disulfides, which go from the inner sphere of the Cu+ complex into a solution. Procedures developed for the determination of amino disulfides, the chemiluminescence determination of H2O2 in the presence of aminothiols as luminescence quenchers, and a modified polarographic procedure for the determination of O2 allowed us to establish that oxidation of aminothiols is not accompanied by catalytic decomposition of H2O2 that formed.
Characterization of the nonheme iron center of cysteamine dioxygenase and its interaction with substrates
Wang, Yifan,Davis, Ian,Chan, Yan,Naik, Sunil G.,Griffith, Wendell P.,Liu, Aimin
, p. 11789 - 11802 (2020)
Cysteamine dioxygenase (ADO) has been reported to exhibit two distinct biological functions with a nonheme iron center. It catalyzes oxidation of both cysteamine in sulfur metabolism and N-terminal cysteine-containing proteins or peptides, such as regulator of G protein signaling 5 (RGS5). It thereby preserves oxygen homeostasis in a variety of physiological processes. However, little is known about its catalytic center and how it interacts with these two types of primary substrates in addition to O2. Here, using electron paramagnetic resonance (EPR), M?ssbauer, and UV-visible spectroscopies, we explored the binding mode of cysteamine and RGS5 to human and mouse ADO proteins in their physiologically relevant ferrous form. This characterization revealed that in the presence of nitric oxide as a spin probe and oxygen surrogate, both the small molecule and the peptide substrates coordinate the iron center with their free thiols in a monodentate binding mode, in sharp contrast to binding behaviors observed in other thiol dioxygenases. We observed a substrate-bound B-type dinitrosyl iron center complex in ADO, suggesting the possibility of dioxygen binding to the iron ion in a side-on mode. Moreover, we observed substrate-mediated reduction of the iron center from ferric to the ferrous oxidation state. Subsequent MS analysis indicated corresponding disulfide formation of the substrates, suggesting that the presence of the substrate could reactivate ADO to defend against oxidative stress. The findings of this work contribute to the understanding of the substrate interaction in ADO and fill a gap in our knowledge of the substrate specificity of thiol dioxygenases.
Fluorescein Chemiluminescence-Delay Method for the Determination of Ultratrace Amounts of Copper(II)
Kamidate, Tamio,Kuniya, Isao,Segawa, Tadashi,Watanabe, Hiroto
, p. 887 - 890 (1992)
A delayed chemiluminescence (CL) was observed in the copper(II)-catalyzed oxidation of cysteamine with oxygen in the presence of fluorescein (FL) and horseradish peroxidase.The delayed CL reaction of FL was applied to the determination of Cu(II).The delay time was correlated linearly with Cu(II) concentration over the range from 5.0 * 10-9 M to 1.0 * 10-6 M.
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Moree,W.J.,Van Der Marel,G.A.,Liskamp,R.M.
, p. 409 (1991)
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Mechanistic scrutiny of the oxidations of thiol-containing drugs cysteamine and d-penicillamine by cis-diamminetetrachloroplatinum(IV)
Zhou, Li,Li, Tiejian,Sun, Ying,Tian, Hongwu,Gao, Cunxiu,Liu, Chunli,Kong, Lingli,Zhang, Guimin,Shi, Tiesheng
supporting information, p. 548 - 557 (2020/12/18)
Cysteamine (CA) and d-penicillamine (Pen) are the thiol-containing drugs and good antioxidants. Their reactions with a cisplatin Pt(IV) prodrug cis-diamminetetrachloroplatinum(IV) (cis-[Pt(NH3)2Cl4]) were investigated by use of rapid scan, stopped-flow, and mass spectral techniques. The kinetic traces are biphasic in nature, encompassing a faster reduction of cis-[Pt(NH3)2Cl4] to cisplatin followed by slow substitutions on cisplatin. The reduction reactions were demonstrated to follow overall second-order kinetics over a wide pH range. The observed second-order rate constants versus pH profiles were established at 25.0°C and 1.0?M ionic strength, indicating a huge increase of reaction rate with the increase of pH. However, the oxidations of CA and Pen by cis-[Pt(NH3)2Cl4] displayed different reaction stoichiometric ratios as revealed by the spectrophotometric titration experiments. Accordingly, CA was oxidized to CA-disulfide while Pen-sulfinic acid and Pen-disulfide were identified as the major products in the case of Pen via mass spectral analysis. The above similarities and differences are rationalized in terms of the proposed reaction mechanisms, which encompass similar rate-determining reactions for both CA and Pen, but involve disparate and faster followed-up reactions. Rate constants of the rate determining were derived at 25.0°C and 1.0?M ionic strength. A consequent species reactivity analysis revealed that the species -SCH2CH2NH3+ of CA and the species +H3NCH(COO?)CMe2S? of Pen played a predominant role toward the reduction of cis-[Pt(NH3)2Cl4] from pH 5 to 8, which also is a critical pH region for most of drugs.
Accelerated reduction and solubilization of elemental sulfur by 1,2-aminothiols
Stoffel, Jonathan T.,Riordan, Kimberly T.,Tsui, Emily Y.
supporting information, p. 12488 - 12491 (2021/12/04)
Nucleophilic 1,2-aminothiol compounds readily reduce typically-insoluble elemental sulfur to polysulfides in both water and nonpolar organic solvents. The resulting anionic polysulfide species are stabilized through hydrogen-bonding interactions with the proximal amine moieties. These interactions can facilitate sulfur transfer to alkenes.
