ESNOQ, Proteomic Quantification of Endogenous S-Nitrosation

S-nitrosation is a post-translational protein modification and is one of the most important mechanisms of NO signaling. Endogenous S-nitrosothiol (SNO) quantification is a challenge for detailed functional studies. Here we developed an ESNOQ (Endogenous SNO Quantification) method which combines the stable isotope labeling by amino acids in cell culture (SILAC) technique with the detergent-free biotin-switch assay and LC-MS/MS. After confirming the accuracy of quantification in this method, we obtained an endogenous S-nitrosation proteome for LPS/IFN-γ induced RAW264.7 cells. 27 S-nitrosated protein targets were confirmed and using our method we were able to obtain quantitative information on the level of S-nitrosation on each modified Cys. With this quantitative information, over 15 more S-nitrosated targets were identified than in previous studies. Based on the quantification results, we found that the S-nitrosation levels of different cysteines varied within one protein, providing direct evidence for differences in the sensitivity of cysteine residues to reactive nitrosative stress and that S-nitrosation is a site-specific modification. Gene ontology clustering shows that S-nitrosation targets in the LPS/IFN-γ induced RAW264.7 cell model were functionally enriched in protein translation and glycolysis, suggesting that S-nitrosation may function by regulating multiple pathways. The ESNOQ method described here thus provides a solution for quantification of multiple endogenous S-nitrosation events, and makes it possible to elucidate the network of relationships between endogenous S-nitrosation targets involved in different cellular processes

Nitric Oxide Destabilizes Pias3 and Regulates Sumoylation

Small ubiquitin-related protein modifiers (SUMO) modification is an important mechanism for posttranslational regulation of protein function. However, it is largely unknown how the sumoylation pathway is regulated. Here, we report that nitric oxide (NO) causes global hyposumoylation in mammalian cells. Both SUMO E2 conjugating enzyme Ubc9 and E3 ligase protein inhibitor of activated STAT3 (Pias3) were targets for S-nitrosation. S-nitrosation did not interfere with the SUMO conjugating activity of Ubc9, but promoted Pias3 degradation by facilitating its interaction with tripartite motif-containing 32 (Trim32), a ubiquitin E3 ligase. On the one hand, NO promoted Trim32-mediated Pias3 ubiquitination. On the other hand, NO enhanced the stimulatory effect of Pias3 on Trim32 autoubiquitination. The residue Cys459 of Pias3 was identified as a target site for S-nitrosation. Mutation of Cys459 abolished the stimulatory effect of NO on the Pias3-Trim32 interaction, indicating a requirement of S-nitrosation at Cys459 for positive regulation of the Pias3-Trim32 interplay. This study reveals a novel crosstalk between S-nitrosation, ubiquitination, and sumoylation, which may be crucial for NO-related physiological and pathological processes

Reducing dephosphorization of silicomanganese ferroalloys by CaO-based slag

The reducing dephosphorization of silicomanganese ferroalloys by CaO-based slags is investigated in the present paper. Experiments are carried out in an induction furnace in air atmosphere to simulate the practical production condition. It is found that dephosphorization took place very quickly by using CaO-CaF2 slag. In addition, decarburization and desulfurization also happened with the dephosphorization process. There is almost no dephosphorization when the silicon content in silicomanganese ferroalloy melt is less than 10 wt.%, while the dephosphorization ratio increases significantly as the silicon content is larger than 10 wt.%. When CaF2 in the slag is partly replaced by Al2O3, the dephosphorization ratio decreases sharply, and there is almost no dephosphorization for CaO-Al2O3 slag even when silicon content in the ferroalloy melt is 22 wt.%.</p

The Role of Silica in the Chlorination-Volatilization of Cobalt Oxide by Using Calcium Chloride

The role of silica in the chlorination-volatilization of cobalt oxide, using calcium chloride, is investigated in this paper. It is found that the Co volatilization percentage of the CoO-Fe2O3-CaCl2 system is not larger than 12.1%. Silica plays an important role in the chlorination-volatilization of cobalt oxide by using calcium chloride. In the CoO-SiO2-Fe2O3-CaCl2 system, the Co volatilization percentage is initially positively related to the molar ratio of SiO2 to CaCl2, and remains almost constant when the molar ratio of SiO2 to CaCl2 rises from zero to eight. The critical molar ratios of SiO2 to CaCl2 are 1 and 2 when the molar ratios of CaCl2 to CoO are 8.3 and 16.6, respectively. The Co volatilization percentage remains almost constant with the increase in CaO concentration, and decreases when Al2O3 and MgO are added. Ca2SiO3Cl2 is determined after roasting at 1073 K and 1173 K, and disappears at temperatures in excess of 1273 K in the calcines from the CoO-SiO2-CaCl2 system. CaSiO3 always exists in the calcines at temperatures in excess of 973 K

Effect of Surface Deposition Coating with Aluminum Hydroxide on the Stabilization of Iron-Arsenic Precipitates

Iron-arsenic coprecipitate is a kind of solid waste produced in the treatment of arsenic-bearing wastewater from non-ferrous metallurgy. Stability of amorphous coprecipitates is usually poor if the Fe/As ratio is lower. In this study, the surface of coprecipitates was deposited with aluminum hydroxide with the aim to prevent the release of arsenic. The deposition experiments were carried out at normal temperature using Al-2(SO4)(3) solutions with pH between the range of 6.0-7.0. The characterization of the coated precipitates was investigated using SEM-EDS, TEM, XRD, FTIR, and BET. The stability experiment showed that the coated precipitates exhibit a higher release of arsenic than the coprecipitates without coating. The anion exchange might have taken place in the coated surface, and the release of arsenic may be a comprehensive result

Eco-friendly and rapid extraction of gold by in-situ catalytic oxidation with N-bromosuccinimide

Gold is a valued, critical element whose chemical activation or extraction is challenging. Non-cyanide extraction of gold is now the focus, and N-bromosuccinimide(NBS) is attracting attention. Herein, new insights into the possible mechanism are deeply revealed through comprehensive analysis and detection of the reaction by using elementary gold and gold bearing ore. Experiments on gold foil indicate that Au can be activated in NBS solution to perform a satisfactory dissolution. Application of NBS in gold extraction from ore show a high yield of 86.24% under optimal conditions of NBS dosage 0.05 M, liquid-solid ratio 4:1, stirring speed 400 rpm, pH 8, 25 degrees C and leaching for 20 h, while yields of other coexisting metals are nearly negligible. The process leads to direct, efficient, one-pot conversion of gold, into simple water-soluble salts. Characterizations show that the framework of NBS are not destroyed, only bromine separates from the framework. The oxidation of neutral gold atom to trivalent Au-(III) occurs in a mild, clean and room-temperature chemistry, which converts gold to [AuBr4](-), and the framework to succinimide. The active bromine and radical Br (Br center dot) generated from in-situ autocatalysis of NBS are responsible for this. The systematic results herald a green procedure for preparation of gold derivatives and gold extraction industry

silverdissolutioninanovelleachingsystemreactionkineticsstudy

Effective silver recovery is usually restricted by either environmental pollution or high recovery costs.To tackle the issues,this study introduces a novel method for the effective recovery of silver by utilizing the alkaline sodium thiosulfate-potassium ferricyanide leaching system.The reaction kinetics of silver dissolution in this system was investigated via the rotating disk electrode technology.The influences of important parameters,including the rotation speed,sodium thiosulfate concentration,potassium ferricyanide concentration,and temperature,on the silver dissolution rate were systematically investigated.The activation energy was measured to be 17.96 kJ·mol^-1 when the silver dissolution was controlled by a diffusion process.When the silver dissolution was in the region of mixed control,the reaction orders of ferricyanide and thiosulfate were found to be 0.57 and 0.19,respectively,and the reaction orders of ferricyanide and thiosulfate were 0.55 and 0.22,respectively,when the silver dissolution was controlled by surface reaction.This study has great potential for the development of an environmentally friendly silver recovery process from end-of-life products

silverdissolutioninanovelleachingsystemreactionkineticsstudy

Effective silver recovery is usually restricted by either environmental pollution or high recovery costs. To tackle the issues, this study introduces a novel method for the effective recovery of silver by utilizing the alkaline sodium thiosulfate-potassium ferricyanide leaching system. The reaction kinetics of silver dissolution in this system was investigated via the rotating disk electrode technology. The influences of important parameters, including the rotation speed, sodium thiosulfate concentration, potassium ferricyanide concentration, and temperature, on the silver dissolution rate were systematically investigated. The activation energy was measured to be 17.96 kJmol(-1) when the silver dissolution was controlled by a diffusion process. When the silver dissolution was in the region of mixed control, the reaction orders of ferricyanide and thiosulfate were found to be 0.57 and 0.19, respectively, and the reaction orders of ferricyanide and thiosulfate were 0.55 and 0.22, respectively, when the silver dissolution was controlled by surface reaction. This study has great potential for the development of an environmentally friendly silver recovery process from end--of-life products

Green Treatment of Cyanide Tailings Using a "Filter Press BackWash-Chemical Precipitation-Gaseous Membrane Absorption" Method

Based on a "filter press backwash-chemical precipitation-gaseous membrane absorption" process, treatment of harmless cyanide tailings was conducted using cyanide tailings from a gold smelting enterprises (Yunnan Province, China) as the research object. The effects of air-drying time, backwash water parameters, initial pH of acidification, NaHS dosage, cyanide-containing water flow rate, and gaseous membrane stages on the process were investigated. Chemical composition, X-ray diffraction, and X-ray photoelectron spectroscopy analyses of the copper products were carried out. Results showed that the copper content in the copper product was 54.56%, and the chemical composition was mainly CuSCN, CuS, Cu2S, and CaSO4. Five cycles of experiments were carried out under optimal conditions; the results showed that the process can make the treated cyanide tailings meet the requirements of the technical specification for pollution control of cyanide leaching residue in the gold industry (TSPC) standard for storage in a tailings pond and a have certain stability. The average recovery rate of copper and total cyanide in elution water was 97.8% and 99.89%, respectively, and the average removal rate of thiocyanate was 94.09%

Eco-friendly and rapid extraction of gold by in-situ catalytic oxidation with N-bromosuccinimide

Gold is a valued, critical element whose chemical activation or extraction is challenging. Non-cyanide extraction of gold is now the focus, and N-bromosuccinimide(NBS) is attracting attention. Herein, new insights into the possible mechanism are deeply revealed through comprehensive analysis and detection of the reaction by using elementary gold and gold bearing ore. Experiments on gold foil indicate that Au can be activated in NBS solution to perform a satisfactory dissolution. Application of NBS in gold extraction from ore show a high yield of 86.24% under optimal conditions of NBS dosage 0.05 M, liquid-solid ratio 4:1, stirring speed 400 rpm, pH 8, 25 degrees C and leaching for 20 h, while yields of other coexisting metals are nearly negligible. The process leads to direct, efficient, one-pot conversion of gold, into simple water-soluble salts. Characterizations show that the framework of NBS are not destroyed, only bromine separates from the framework. The oxidation of neutral gold atom to trivalent Au-(III) occurs in a mild, clean and room-temperature chemistry, which converts gold to [AuBr4](-), and the framework to succinimide. The active bromine and radical Br (Br center dot) generated from in-situ autocatalysis of NBS are responsible for this. The systematic results herald a green procedure for preparation of gold derivatives and gold extraction industry