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.
-
Moree,W.J.,Van Der Marel,G.A.,Liskamp,R.M.
, p. 409 (1991)
-
Selective, Modular Probes for Thioredoxins Enabled by Rational Tuning of a Unique Disulfide Structure Motif
Becker, Katja,Busker, Sander,Felber, Jan G.,Maier, Martin S.,Poczka, Lena,Scholzen, Karoline,Theisen, Ulrike,Thorn-Seshold, Julia,Thorn-Seshold, Oliver,Zeisel, Lukas,Arnér, Elias S. J.,Brandst?dter, Christina
supporting information, p. 8791 - 8803 (2021/06/27)
Specialized cellular networks of oxidoreductases coordinate the dithiol/disulfide-exchange reactions that control metabolism, protein regulation, and redox homeostasis. For probes to be selective for redox enzymes and effector proteins (nM to μM concentrations), they must also be able to resist non-specific triggering by the ca. 50 mM background of non-catalytic cellular monothiols. However, no such selective reduction-sensing systems have yet been established. Here, we used rational structural design to independently vary thermodynamic and kinetic aspects of disulfide stability, creating a series of unusual disulfide reduction trigger units designed for stability to monothiols. We integrated the motifs into modular series of fluorogenic probes that release and activate an arbitrary chemical cargo upon reduction, and compared their performance to that of the literature-known disulfides. The probes were comprehensively screened for biological stability and selectivity against a range of redox effector proteins and enzymes. This design process delivered the first disulfide probes with excellent stability to monothiols yet high selectivity for the key redox-Active protein effector, thioredoxin. We anticipate that further applications of these novel disulfide triggers will deliver unique probes targeting cellular thioredoxins. We also anticipate that further tuning following this design paradigm will enable redox probes for other important dithiol-manifold redox proteins, that will be useful in revealing the hitherto hidden dynamics of endogenous cellular redox systems.
Self-Polymerization Promoting Monomers: In Situ Transformation of Disulfide-Linked Benzoxazines into the Thiazolidine Structure
Monisha, Monisha,Sahu, Sangeeta,Lochab, Bimlesh
, p. 4408 - 4421 (2021/10/20)
Polybenzoxazines obtained especially from green synthons are facing challenges of the requirement of high ring-opening polymerization (ROP) temperature of the monomer, thus affecting their exploration at the industrial front. This demands effective structural changes in the monomer itself, to mediate catalyst-free polymerization at a low energy via one-step synthesis protocol. In this regard, monomers based on disulfide-linked bisbenzoxazine were successfully synthesized using cystamine (biobased) and cardanol (agro-waste)/phenol. Reduction of the disulfide bridge in the monomer using dithiothreitol under mild conditions in situ transformed the oxazine ring in the monomer, via neighboring group participation of the -SH group in a transient intermediate monomer, into a thiazolidine structure, which is otherwise difficult to synthesize. Structural transformation of ring-opening followed by the ring-closing intramolecular reaction led to an interconversion of O-CH2-N containing a six-membered oxazine ring to S-CH2-N containing a five-membered thiazolidine ring and a phenolic-OH. The structure of the monomer with the oxazine ring and its congener with the thiazolidine ring was characterized by spectroscopic methods and X-ray analysis. Kinetics of structural transformation at a molecular level is studied in detail, and it was found that the reaction proceeded via a transient 2-aminoethanethiol-linked benzoxazine intermediate, as supported by nuclear magnetic resonance spectroscopy and density functional theory studies. The thiazolidine-ring-containing monomer promotes ROP at a substantially low temperature than the reported mono-/bisoxazine monomers due to the dual mode of facilitation of the ROP reaction, both by phenolic-OH and by ring strain. Surprisingly, both the monomer structures led to the formation of a similar polymer structure, as supported by thermogravimetric analysis and Fourier transform infrared study. The current work highlights the benefits of inherent functionalities in naturally sourced feedstocks as biosynthons for the new latest generation of benzoxazine monomers.
