35100-73-3Relevant academic research and scientific papers
Kinetics and mechanism for the reaction of cysteine with hydrogen peroxide in amorphous polyvinylpyrrolidone lyophiles
Luo, Dayong,Anderson, Bradley D.
, p. 2239 - 2253 (2006)
Purpose. Peroxide impurities play a critical role in drug oxidation. In metal-free aqueous solutions, hydrogen peroxide (H2O2) induced thiol oxidation involves a bimolecular nucleophilic reaction to form a reactive sulfenic acid intermediate (RSOH), which reacts with a second thiol to form a disulfide (RSSR). This study examines the reaction of cysteine (CSH) and H2O2 in amorphous polyvinylpyrrolidone (PVP) lyophiles to explore the possible relevance of the solution mechanism to reactivity in an amorphous glass. Materials and Methods. Amorphous PVP lyophiles containing CSH and H2O2 at varying initial 'pH' and reactant concentrations were prepared by methods designed to minimize reaction during lyophilization. Kinetic studies were conducted anaerobically at 25°C and reactants and products were monitored by HPLC. Products were characterized and the kinetic data were fit to models adapted from the solution mechanism. Results. Key differences in the reactions in aqueous solution and amorphous PVP are: (1) while only cystine (CSSC) forms in solution, three degradants-cysteine sulfinic acid (CSO2H), cysteine sulfonic acid (CSO3H) and cystine (CSSC)-form in amorphous PVP; (2) simple bimolecular kinetics govern the solution reaction while initial rates in amorphous PVP suggested more complex kinetics (i.e., non-unity values for reaction order); and (3) heterogeneous (i.e., biphasic) reaction dynamics are evident in amorphous PVP. The differences in product formation and apparent reaction orders in the solid-state could be rationalized by partitioning of the same reactive intermediate to multiple products in the solid-state due to the restricted mobility of CSH. Beyond the initial rate region, the kinetics in amorphous PVP could be described by the Kohlrausch-Williams-Watts (KWW) stretched-exponential equation or by assuming two populations of reactant molecules having different reactivities. Conclusions. When reactive intermediates are involved, differences in degradant profiles and other characteristics (e.g., rate constants, apparent reaction order) in the amorphous-state may simply reflect altered rates for individual reaction steps due to glass-induced changes in relative reactant mobilities rather than a change in overall mechanism.
Electropolymerization of cobalt tetraamino-phthalocyanine at reduced graphene oxide for electrochemical determination of cysteine and hydrazine
Mani, Veerappan,Huang, Sheng-Tung,Devasenathipathy, Rajkumar,Yang, Thomas C. K.
, p. 38463 - 38469 (2016/05/19)
We describe a simple and elegant electropolymerization method to prepare highly stable tetraamino functionalized cobalt phthalocyanine (pTACoPc) at electrochemically reduced graphene oxide (RGO). The described method efficiently bridges the excellent physicochemical properties of RGO with the rich redox chemistry of TACoPc. Graphene oxide was electrochemically reduced to RGO at the electrode surface along with concominent electropolymerization of TACoPc. The electrochemical studies showed that RGO on pTACoP/GCE increased effective surface area, reduced charge transfer resistance and enhanced electrochemical signal. The RGO-pTACoPc film modified electrode exhibits excellent electrocatalytic ability to oxidize cysteine and hydrazine. To determine cysteine, the RGO-pTACoPc sensor displayed a linear concentration range of 50 nM to 2.0 μM, detection limit of 18.5 nM and sensitivity of 10.19 nA nM-1 cm-2. Besides, the sensor displayed a linear concentration range of 50 nM to 2.6 μM, detection limit of 10 nM and sensitivity of 1.62 nA nM-1 cm-2 to determine hydrazine. The electrocatalytic ability of RGO-pTACoPc shows better performance over other cobalt phthalocyanine derivatives. Furthermore, the described sensor exhibited long-term storage stability, good repeatability and reproducibility. The practical applicability of the sensor has been assessed in biological and water samples.
Nitrite reduction mediated by the complex RuIII(EDTA)
Chatterjee, Debabrata,Shome, Sanchari,Jaiswal, Namita,Banerjee, Priyabrata
, p. 13596 - 13600 (2014/11/08)
Reported is the first example of a ruthenium(iii)-complex, Ru III(EDTA) (EDTA4- = ethylenediaminetetraacetate), that mediates O-atom transfer from nitrite to the biological thiols cysteine and glutathione, leading to the formation of [RuIII(EDTA)(NO +)]0. However, at pH below 5.0, the coordinated nitrite ion in the [RuIII(EDTA)(NO2)]2- complex undergoes proton-assisted decomposition, resulting in the formation of a [RuIII(EDTA)(NO+)]0 species. the Partner Organisations 2014.
S-aroylthiooximes: A facile route to hydrogen sulfide releasing compounds with structure-dependent release kinetics
Foster, Jeffrey C.,Powell, Chadwick R.,Radzinski, Scott C.,Matson, John B.
supporting information, p. 1558 - 1561 (2014/04/17)
We report the facile preparation of a family of S-aroylthiooxime (SATO) H2S donors, which are synthesized via a click reaction analogous to oxime formation between S-aroylthiohydroxylamines (SATHAs) and aldehydes or ketones. Analysis of cysteine-triggered H2S release revealed structure-dependent release kinetics with half-lives from 8-82 min by substitution of the SATHA ring. The pseudo-first-order rate constants of substituted SATOs fit standard linear free energy relationships (p = 1.05), demonstrating a significant sensitivity to electronic effects.
Live-cell imaging of cyclopropene tags with fluorogenic tetrazine cycloadditions
Yang, Jun,?e?kute, Jolita,Cole, Christian M.,Devaraj, Neal K.
supporting information; scheme or table, p. 7476 - 7479 (2012/09/08)
Spotlight on lipids: One of the major limitations of tetrazine bioorthogonal cycloadditions is the requirement of bulky dienophile reaction partners. Methylcyclopropene tags were designed capable of reacting rapidly with tetrazines while maintaining stability in aqueous solution. The suitability of these probes for bioconjugation is shown by imaging cyclopropene-modified phospholipids in live human cancer cells (see picture). Copyright
Investigation of reactions postulated to occur during inhibition of ribonucleotide reductases by 2′-azido-2′-deoxynucleotides
Dang, Thao P.,Sobczak, Adam J.,Mebel, Alexander M.,Chatgilialoglu, Chryssostomos,Wnuk, Stanislaw F.
experimental part, p. 5655 - 5667 (2012/09/25)
Model 3′-azido-3′-deoxynucleosides with thiol or vicinal dithiol substituents at C2′ or C5′ were synthesized to study reactions postulated to occur during inhibition of ribonucleotide reductases by 2′-azido-2′-deoxynucleotides. Esterification of 5′-(tert-
Identification and characterization of the first ovothiol biosynthetic Enzyme
Braunshausen, Andrea,Seebeck, Florian P.
supporting information; experimental part, p. 1757 - 1759 (2011/04/15)
Ovothiols are histidine-derived thiols that were first isolated from marine invertebrates. We have identified a 5-histidylcysteine sulfoxide synthase (OvoA) as the first ovothiol biosynthetic enzyme and characterized OvoAs from Erwinia tasmaniensis and Trypanosoma cruzi. Homologous enzymes are encoded in more than 80 genomes ranging from proteobacteria to animalia.
NOVEL FORMULATION OF DEHYDRATED LIPID VESICLES FOR CONTROLLED RELEASE OF ACTIVE PHARMACEUTICAL INGREDIENT VIA INHALATION
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, (2009/03/07)
A new formulation of dehydrated lipid vesicles employs a vesicle preserver and permits the control of release and delivery of active pharmaceutical ingredients into the respiratory system for treatment in particular of asthma. The typical formulation provides controlled release of the active pharmaceutical ingredient from 0% to 100% from 0 to 72 hours after inhalation, changes the systemic administration to topical administration, allows prolonged therapeutic period for one administration, increased stability, with reduced dose, reduced systemic side effects, reduced toxicity.
Acylated Exendin-4 Compounds
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, (2009/12/28)
This invention provides new therapeutic peptides, i.e. new protracted Exendin-4 compounds, pharmaceutical compositions and the use of such.
Fe(HSO4)3 and Fe(HSO4)3/DMSO as efficient, heterogeneous, and reusable catalyst systems for the oxidative coupling of thiols
Eshghi,Bakavoli,Moradi,Davoodnia
experimental part, p. 3110 - 3118 (2010/04/24)
Fe(HSO4)3 has been used as a heterogeneous, efficient, and recyclable catalyst in ethanol for the selective oxidation of thiols to their corresponding disulfides. The same results were obtained under identical conditions using catalytic amounts of Fe(HSO4)3 in the presence of DMSO. Different types of aliphatic, aromatic, and heteroaromatic thiols have been used in the reaction, and in all cases the products were obtained in good to excellent yields.
