56-89-3Relevant articles and documents
A REINVESTIGATION OF THE OXIDATION OF CYSTEINE BY Br2(1-)(.) AND I2(1-)(.). EVIDENCE FOR CySBr(1-) AND CySI(1-).
Packer, John E.
, p. 1015 - 1024 (1984)
The existence of the species CySBr(1-) and CySI(1-), which may be regarded as complexes between the thiyl radical from cysteine and bromide or iodide ions, is reported, and their properties discussed in relation to other sulphur- and halogen- containing species which also, have a three-electron half-order bond.The oxidation of cysteine by I2(1-)(.) is shown to be much more complex than hitherto reported, and pH-dependent equilibria involving iodine atoms, iodide ions, cysteine, and cysteinyl radicals are described.The first measured rate constant for the reaction of iodine (as I3(1-)) with a thiol is also reported.
Hierarchical cystine flower based electrochemical genosensor for detection of Escherichia coli O157:H7
Pandey, Chandra Mouli,Tiwari, Ida,Sumana, Gajjala
, p. 31047 - 31055 (2014)
This work reports on a facile and reproducible approach to synthesize novel organic flowers of cystine (CysFls) with high uniformity. These 3D flower-like structures have a purely hierarchical arrangement, wherein each petal is composed of several cystine molecules with an average size of 50 μM, as determined by transmission electron microscopy. The CysFls were self-assembled onto a gold electrode and were utilized as matrices for the covalent immobilization of an Escherichia coli O157:H7 (E. coli) specific probe oligonucleotide that was identified from the 16s rRNA coding region of the E. coli genome. This fabricated CysFl platform sought to provide improved fundamental characteristics to electrode interface in terms of electro-active surface area and diffusion coefficient. Electrochemical impedance spectroscopy revealed that this genosensor exhibits a linear response to complementary DNA in the concentration range of 10-6 to 10-15 M with a detection limit of 1 × 10-15 M. Under optimal conditions, this genosensor was found to retain about 88% of its initial activity after being used for 6 times. This journal is the Partner Organisations 2014.
Simple and facile preparation of silver-polydopamine (Ag-PDA) core-shell nanoparticles for selective electrochemical detection of cysteine
Thota, Raju,Ganesh
, p. 49578 - 49587 (2016)
Selective and sensitive non-enzymatic electrochemical detection of cysteine (CySH) is achieved in the present work using a polydopamine capped silver nanoparticles (Ag-PDA) modified indium tin oxide (ITO) electrode. Efficient redox properties, synergistic effects and the specific steric hindrance associated with the Ag-PDA core-shell nanoparticles provide higher selectivity and larger sensitivity for CySH detection over other competitive bio-thiols namely, homo-cysteine and glutathione. A simple one-step method is used for the preparation of Ag-PDA core-shell nanoparticles. The structure, morphology and composition of Ag-PDA nanoparticles are characterized by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-visible (UV-vis) and Fourier transform infra red (FTIR) spectroscopic techniques. Electrochemical characteristics are investigated by using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). These studies clearly reveal the formation of Ag-PDA nanocomposite on the ITO electrodes and their corresponding redox properties. Non-enzymatic electrochemical detection of CySH is carried out using Ag-PDA modified ITO electrodes in 0.1 M PBS (pH = 5.0) aqueous solution. Under the optimized conditions, this particular electrochemical biosensor exhibits a perfect linear calibration plot in the concentration range between 0.05 μM and 300 μM. Further, a sensitivity value of 0.023 μA μM-1 and a lower detection limit of 0.02 μM are determined for CySH detection. Moreover this Ag-PDA modified ITO electrode is applied further for the determination of CySH in human blood serum samples and the results are promising and satisfactory, suggesting the possible analytical application of this biosensor for the determination of CySH in biological samples.
An unusual electrochemical oxidation of phenothiazine dye to phenothiazine-bi-1,4-quinone derivative (a donor-acceptor type molecular hybrid) on MWCNT surface and its cysteine electrocatalytic oxidation function
Shanmugam, Ranganathan,Barathi, Palani,Zen, Jyh-Myng,Kumar, Annamalai Senthil
, p. 34 - 45 (2016)
Phenothiazine (PTZ), a thiazine class heterocyclic compound, is a well-known electron donating system and has been widely used as a starting compound to prepare various phenothiazine dyes and pharmaceutically important compounds. Quinones and its derivatives are constituents of biologically active molecules serve as excellent electron-acceptor systems. Oxidation of PTZ by chemical and electrochemical methods often resulted into monohydroxylation of benzene ring moiety, S-oxidized and polymerized compounds as end products. Electrochemical oxidation of PTZ on a multiwalled carbon nanotube (MWCNT) modified glassy carbon electrode in pH 7 phosphate buffers solution (PBS) has been investigated in this work. A highly redox active surface confined PTZ-bi-1,4-quinone derivative (PTZ-biQ) on MWCNT modified glassy carbon electrode, designated as GCE/MWCNT@PTZ-biQ, as a product was unusually observed. The GCE/MWCNT@PTZ-biQ showed well-defined redox peaks at E1/2 = -0.07 and +0.29 V vs Ag/AgCl corresponding to surface confined electron-transfer behavior of the bi-quinone (acceptor) and PTZ-cationic radical species (donor) respectively. No such electrochemical characteristics were noticed when unmodified GCE was subjected to the electrochemical oxidation of PTZ. Existence of PTZ-biQ was confirmed by XRD, Raman spectroscopy, FT-IR and GC-MS (methanolic extract of the active layer) analyses. Position of biQ in PTZ-biQ as 1,4-quinone isomer was confirmed by observation of absence of copper-complexation with 1,4-quinone and H2O2 electrochemical reduction reactions at -0.1 V vs Ag/AgCl unlike to the specific copper-complexation and H2O2 reduction with 1,2-quinone isomer in pH 7. Cysteine (CySH) oxidation was studied as a model system to understand the electron-transfer function of the MWCNT@PTZ-biQ. A highly selective electrocatalytic oxidation and sensing by amperometric i-t and flow injection analysis of CySH at low oxidation potential, 0.3 V vs Ag/AgCl in pH 7 PBS with detection limit values (signal-to-noise ratio = 3) of 11.10 μM and 110 nM respectively, without any interference from other biochemicals like uric acid, dopamine, nitrite, citric acid and H2O2, unlike the conventional chemically modified electrodes with serious interference's, have been demonstrated.
Utzinger
, (1960)
A cytotoxic tantalum(v) half-sandwich complex: A new challenge for metal-based anticancer agents
?tarha, Pavel,Trávní?ek, Zdeněk,Dvo?ák, Zdeněk
, p. 9533 - 9536 (2018)
Despite the biological relevance of complexes of various transition metals, tantalum complexes have long been neglected by bioinorganic chemists. Herein, we demonstrate potential chemotherapeutic applicability of the [Ta(η5-Cp?)Cl2(salaph)] (1) complex, containing deprotonated Schiff base 2-{(E)-[(2-hydroxyphenyl)imino]methyl}phenol (H2salaph), which shows strong cytotoxicity in cancer cells, related to the induction of apoptosis and apoptosis-related processes, but shows low cytotoxicity in healthy cells.
Redox Chemistry of [Fe2(CN)10]4-. Part 4 Reaction with L-Cysteine
Beckford, Floyd A.,Bennet, Deon,Dasgupta, Tara P.,Stedman, Geoffrey
, p. 98 - 99 (1998)
L-Cysteine reduces [Fe2(CN)10]4- to [Fe2(CN)10]6- in a two stage process, a rapid reduction to [Fe2(CN)10]6- followed by a slower second order reaction involving HSCH2CH (NH3+CO2- and a conjugate base.
Synthesis of Cystine-peptide by a New Disulphide Bond-forming Reaction using the Silyl Chloride-Sulphoxide System
Akaji, Kenichi,Tatsumi, Tadashi,Yoshida, Makoto,Kimura, Tooru,Fujiwara, Yoichi,Kiso, Yoshiaki
, p. 167 - 168 (1991)
Methyltrichlorosilane or tetrachlorosilane in trifluoroacetic acid, in the presence of diphenylsulphoxide, is found to cleave various S-protecting groups of cysteine to form cystine directly by the reduction-oxidation reaction; this new disulphide bond forming reaction is successfully applied to the syntheses of oxytocin and human brain natriuretic peptide.
A simple and efficient fluorescent sensor for histidine
Huang, Zeng,Du, Jiao,Zhang, Jing,Yu, Xiao-Qi,Pu, Lin
, p. 3412 - 3414 (2012)
A simple coordination complex terpyridine-CuCl2 is found to be an efficient fluorescent sensor for histidine in aqueous solution with up to 1004 fold fluorescence enhancement.
Adduct Formation and Absolute Rate Constants in the Displacement Reaction of Thiyl Radicals with Disulfides
Bonifacic, M.,Asmus, K.-D.
, p. 6286 - 6290 (1984)
The displacement reaction of thiyl radicals with disulfides is shown to proceed via a transient adduct radical by using time-resolved pulse radiolysis techniques.The relatively long-lived adduct (t1/2 > 100 μs) formed in the forward reaction of the equilibrum RS. + RSSR . is suggested to be a sulfuranyl radical with the unpaired electron located in an antibonding ?* orbital within a trisulfide bridge.These species exhibit optical absorptions in the UV, e.g., λmax = 375 +/- 10 nm and ε = (3.4 +/- 0.4)*103 M-1 cm-1 for the all-methylated radical, and have been identified in aqueous and methanolic solutions.Equilibrum constants of K = 180 +/- 30 and 60 +/- 20 M-1 have been evaluated for the systems with R = CH3 and cysteine residue, respectively, via two different methods.The corresponding forward reactions occur with k(RS. + RSSR) = 3.8*106 and 7.7*105 M-1 s-1, respectively.
Formation, characterization and electrochemical properties of novel tetrasubstituted cobalt phthalocyanines bearing tetrahydropyran, furan and coumarin moieties
Chohan, Sumayya,Booysen, Irvin Noel,Mambanda, Allen,Akerman, Matthew Piers
, p. 183 - 191 (2016)
Cobalt phthalocyanines (CoPcs) bearing peripherally tetrasubstituted tetrahydropyran (thp) or furan (fur) moieties were formed and spectroscopically characterized. Structural elucidations of 4-(tetrahydropyran-2-methoxy)phthalonitrile (1) and 4-(furan-2-methylthio)phthalonitrile (2) were confirmed via single crystal X-ray analysis. The redox properties of CoPc-thp (3) and CoPc-fur (4) were investigated via cyclic and squarewave voltammetry as well as UV-Vis spectroelectrochemistry. Glassy carbon electrodes (GCEs) modified with 3, 4 and a previously reported coumarin (cou) substituted CoPc (CoPc-cou, 5), were tested for their electrocatalytic activities toward l-cysteine. While the bare GCE and 4-GCE showed no peaks for l-cysteine oxidation in the 0.0-0.70 V potential window; 3-GCE and 5-GCE showed peaks at 0.42 V and 0.52 V, respectively. Kinetic parameters were determined by chronoamperometry studies. l-Cysteine oxidation using 3-GCE was found to proceed at a faster rate than 5-GCE.
Iron(III)–salen ion catalyzed s-oxidation of L-cysteine and s-alkyl-L-cysteines by H2O2: Spectral, kinetic and electrochemical study
Karuppasamy, Periyakaruppan,Thiruppathi, Dharmaraj,Ganesan, Muniyandi,Rajendran, Thangamuthu,Rajagopal, Seenivasan,Sivasubramanian, Veluchamy Kamaraj
, p. 135 - 145 (2019)
The H2O2 oxidation of L-cysteine and s-alkyl-L-cysteines (s-met-L-cys, s-et-L-cys & s-pro-L-cys) catalyzed by iron(III)–salen (salen = N,N′-bis(salicylidene)ethylenediaminato) complexes in aqueous CH3CN proceeds through Michaelis–Menten kinetics. The rate constant (k) values correlate well with Hammett σ constants, which gives the positive reaction constant (ρ = 1.5–1.9) value. The CV of oxoiron(IV)-salen ion shows a clear oxidation peak at 1.28 V in 0.1 M phosphate buffer (PB) solution using 0.1 M tertiary butyl ammonium perchlorate (TBAP) as supporting electrolyte at 266 K. The rate of the reaction is highly sensitive to the length of the alkyl chains present in the L-cysteines, pH and solvent composition of the medium. The calculated binding constant values (Kf) in the range of 117–613 M?1, indicate that iron(III)–salen complexes carrying electron donating substituents in the salen ligand have higher binding constant values compared to those carrying electron withdrawing substituents. Product analysis shows the conversion of L-cys to its disulfide and s-alkyl-L-cys to the corresponding sulfoxides. Based on the spectral and kinetic data the plausible mechanism has been proposed.
Determination of a small quantity of cystine in the presence of a large amount of cysteine
Yamagata, Shuzo,Iwama, Tomonori
, p. 1503 - 1505 (1999)
A procedure is described to precisely determine a very small amount of cystine in the presence of a large amount of cysteine. After completely modifying cysteine with N-ethylmaleimide, the remaining reagent was reacted with DL-homocysteine. Cystine was determined, after being reduced with dithiothreitol, by the reaction with ninhydrin carried out under acidic conditions. The procedure makes it possible to precisely determine the amount of cystine present with cysteine in a concentration ratio of 1:2,000. By employing this procedure, auto-oxidation of cysteine to cystine in a mixture for the L-cysteine α, β-elimination reaction was investigated.
Reduction of RuVI≡N to RuIII - NH3 by Cysteine in Aqueous Solution
Wang, Qian,Man, Wai-Lun,Lam, William W. Y.,Yiu, Shek-Man,Tse, Man-Kit,Lau, Tai-Chu
, p. 5850 - 5858 (2018)
The reduction of metal nitride to ammonia is a key step in biological and chemical nitrogen fixation. We report herein the facile reduction of a ruthenium(VI) nitrido complex [(L)RuVI(N)(OH2)]+ (1, L = N,N′-bis(salicylidene)-o-cyclohexyldiamine dianion) to [(L)RuIII(NH3)(OH2)]+ by l-cysteine (Cys), an ubiquitous biological reductant, in aqueous solution. At pH 1.0-5.3, the reaction has the following stoichiometry: [(L)RuVI(N)(OH2)]+ + 3HSCH2CH(NH3)CO2 → [(L)RuIII(NH3)(OH2)]+ + 1.5(SCH2CH(NH3)CO2)2. Kinetic studies show that at pH 1 the reaction consists of two phases, while at pH 5 there are three distinct phases. For all phases the rate law is rate = k2[1][Cys]. Studies on the effects of acidity indicate that both HSCH2CH(NH3+)CO2- and -SCH2CH(NH3+)CO2- are kinetically active species. At pH 1, the reaction is proposed to go through [(L)RuIV(NHSCH2CHNH3CO2H)(OH2)]2+ (2a), [(L)RuIII(NH2SCH2CHNH3CO2H)(OH2)]2+ (3), and [(L)RuIV(NH2)(OH2)]+ (4) intermediates. On the other hand, at pH around 5, the proposed intermediates are [(L)RuIV(NHSCH2CHNH3CO2)(OH2)]+ (2b) and [(L)RuIV(NH2)(OH2)]+ (4). The intermediate ruthenium(IV) sulfilamido species, [(L)RuIV(NHSCH2CHNH3CO2H)(OH2)]2+ (2a) and the final ruthenium(III) ammine species, [(L)RuIII(NH3)(MeOH)]+ (5) (where H2O was replaced by MeOH) have been isolated and characterized by various spectroscopic methods.
Kinetic Studies of the Oxidation of Thiols by Coenzyme PQQ
Itoh, Shinobu,Kato, Noboyuki,Mure, Minae,Ohshiro, Yoshiki
, p. 420 - 422 (1987)
Kinetic studies on the oxidation of thiols by coenzyme PQQ are carried out under anaerobic conditions.A bell-shaped pH-rate profile having a maximum rate at around pKa of the thiol is observed.The rate-determining step changes between acidic and basic sides of the profile indicating the existence of at least one intermediate in the course of the reaction.
Real-time monitoring of "self-oxidation" of cysteine in presence of Cu2+: novel findings in the oxidation mechanism
Buzuk, Marijo,Brini?, Slobodan,Vladislavi?, Nives,Brali?, Marija,Buljac, Ma?a,Ron?evi?, Ivana ?kugor
, p. 359 - 367 (2016)
A novel approach for investigation of a mechanism and rate of "self-oxidation" of cysteine in the presence of Cu2+ is presented. Continuous monitoring was performed using simple, low-cost, and widely available commercial ion-selective electrode for Cu2+. Presented procedure provides a complete real-time picture of overall oxidation process and has revealed a sequentially organized process, with the domination of certain reactions in each stage. A plausible mechanism, in the light of the previously reported explanation, has been proposed to account for the experimental results together with an adequate scheme of the overall process. The dependence of both the pH (measurements were performed at pH 5, 7, 8) and the concentration of the initially present Cu2+ is presented and discussed. Additionally, information into the process was collected by experiments performed in oxygen-free atmosphere and changes in the mechanism of oxidation, at weakly alkaline pH values, were observed. Information presented in this study can be utilized in advanced biochemical monitoring systems, when considering the importance of the position of cysteine and cysteine containing peptides in metabolic processes.
COPPER-CATALYZED AUTOXIDATION OF CYSTEINE. THE AMOUNT OF HYDROGEN PEROXIDE PRODUCED UNDER VARIOUS CONDITIONS AND THE STOICHIOMETRY OF THE REACTION.
Hanaki,Kamide
, p. 2065 - 2068 (1983)
Hydrogen peroxide is shown to be produced as an intermediate from oxygen in the copper-catalyzed autoxidation of cysteine. The amounts of cysteine oxidized and of hydrogen peroxide formed varied depending on the reaction conditions employed. The peroxide upon forming was spontaneously utilized for the oxidation of cysteine. As a result, the ratio of the concentration of hydrogen peroxide formed to cysteine oxidized is variable depending on the conditions. But, in dilute solutions, where the oxidation by the peroxide was slow, a stoichiometric relation of 2:1 was obtained between cysteine consumed and hdyrogen peroxide produced. The rate of autoxidation is dependent on the concentration of oxygen dissolved. The double reciprocal plot of the rate against the concentration of oxygen gives a straight line, which indicates a possibility of the Michaelis-Menten type mechanism concerning the reoxidation or oxygenation of Cu(I) species.
Metal organic frameworks as nitric oxide catalysts
Harding, Jacqueline L.,Reynolds, Melissa M.
, p. 3330 - 3333 (2012)
The use of metal organic frameworks (MOFs) for the catalytic production of nitric oxide (NO) is reported. In this account we demonstrate the use of Cu 3(BTC)2 as a catalyst for the generation of NO from the biologically occurring substrate, S-nitrosocysteine (CysNO). The MOF catalyst was evaluated as an NO generator by monitoring the evolution of NO in real time via chemiluminescence. The addition of 2, 10, and 15-fold excess CysNO to MOF-CuII sites and cysteine (CysH) resulted in catalytic turnover of the active sites and nearly 100% theoretical yield of the NO product. Control experiments without the MOF present did not yield appreciable NO generation. In separate studies the MOF was found to be reusable over successive iterations of CysNO additions without loss of activity. Subsequently, the MOF catalyst was confirmed to remain structurally intact by pXRD and ATR-IR following reaction with CysNO and CysH.
Reduction of vanadium(IV) to vanadium(III) by cysteine methyl ester in water in the presence of amino polycarboxylates
Kanamori, Kan,Kinebuchi, Yoshiko,Michibata, Hitoshi
, p. 423 - 424 (1997)
The reduction behavior of vanadium(IV) by several thiolate compounds in water was investigated in the presence of amino polycarboxylates. Vanadium(IV) can be reduced by cysteine methyl ester in the presence of edta or cydta to yield [VIII(edta or cydta)(H20)]-, respectively.
Reduction of an asymmetric Pt(IV) prodrug fac-[Pt(dach)Cl3(OC(=O)CH3)] by biological thiol compounds: kinetic and mechanistic characterizations
Huo, Shuying,Ma, Dongying,Song, Changying,Sun, Jingjing,Wang, Yafang
, p. 623 - 631 (2021/11/22)
An asymmetric Pt(IV) prodrug fac-[Pt (dach)Cl3(OC(=O)CH3)] (dach = 1,2-diaminocyclohexane) was synthesized, and the reduction of the Pt(IV) prodrug by three biological thiols glutathione (GSH), cysteine (Cys) and homocysteine (Hcy) was investigated by a stopped-flow spectrometer. All the reductions were followed by an overall second-order reaction with first-order in both [Pt(IV)] and [thiol]. The reduction of the Pt(IV) prodrug occurred through a chloride bridge (Pt-Cl-S) mediated two electron transfer process. Therefore, the coordinated chloride possesses a better bridging effect than the oxygen atom from the coordinated –CH3COO? of the Pt(IV) prodrug. A reactivity trend of k′Cys > k′GSH > k′Hcy is found, illustrating that the reactivity is followed by the trend of Cys > GSH > Hcy in pH 7.4 buffer. Graphical abstract: Transition state is formed between the axially coordinated chloride of the platinum(IV) complex and the sulfur atom from the thiol/thiolate group of Cys/Hcy/GSH.[Figure not available: see fulltext.].
Enhanced Light-Driven Hydrogen Production by Self-Photosensitized Biohybrid Systems
Martins, Mónica,Toste, Catarina,Pereira, Inês A. C.
supporting information, p. 9055 - 9062 (2021/03/15)
Storage of solar energy as hydrogen provides a platform towards decarbonizing our economy. One emerging strategy for the production of solar fuels is to use photocatalytic biohybrid systems that combine the high catalytic activity of non-photosynthetic microorganisms with the high light-harvesting efficiency of metal semiconductor nanoparticles. However, few such systems have been tested for H2 production. We investigated light-driven H2 production by three novel organisms, Desulfovibrio desulfuricans, Citrobacter freundii, and Shewanella oneidensis, self-photosensitized with cadmium sulfide nanoparticles, and compared their performance to Escherichia coli. All biohybrid systems produced H2 from light, with D. desulfuricans-CdS demonstrating the best activity overall and outperforming the other microbial systems even in the absence of a mediator. With this system, H2 was continuously produced for more than 10 days with a specific rate of 36 μmol gdcw?1 h?1. High apparent quantum yields of 23 % and 4 % were obtained, with and without methyl viologen, respectively, exceeding values previously reported.
