Voltammetric Detection of Free Sulfhydryl Compounds in Food Flours

Cyclic voltammetry has been applied to the rapid measurement of free SH‐compounds in food flours samples. The protocol is based on the electrochemical adaptation of the Ellman's test, where the DTNB reacts with SH‐compounds present in food flour extracts, resulting in the equimolar production of the electroactive compound TNBA which, in turns, reacts with phenylendiamine. The reaction is found to provide an analytical signal from which to quantify indirectly free sulfhydryl compounds in flours extracts.     

Protection of immobilized sulfhydryl groups against autooxidation by alterations in their microenvironment

Immobilized sulfhydryl groups were prepared by partial thiolation of NH₂-glass beads. The microenvironment of the immobilized SH groups was varied by different chemical modifications of neighboring NH₂ groups. Introduction of a strong charge in the surroundings of immobilized sulfhydryls results in their dramatic stabilization against autooxidation. This effect is due to the salting of O₂ from the surface microlayer of the thiolated beads.     

Intra- and Inter-molecular Sulf- hydryl Hydrogen Bonding: Facilitating Proton Transfer Events for Determination of pH in Sea Water

This work presents the electrochemical response of a 2-(methylthio)phenol glassy carbon based electrode for a promising voltammetric pH sensor in both buffered and low-buffered solutions. Electropolymerization of the redox species was performed with the resulting polymer presenting a Nernstian response in buffered media, with a sensitivity of 51 mV/pH unit. The effectiveness of the sulfhydryl bond to facilitate proton transfer from the bulk solution to the phenol molecules has been confirmed, providing an accurate pH measurement of 8.28 in sea water media, compared to that measured with a calibrated glass pH probe of 8.30.     

基于分子内电荷转移机制的巯基荧光比色化学传感器

设计并合成了以香豆素为荧光发色团的多氰基分子化合物TCC。分子内强烈的电荷转移效应使得其本身荧光较弱。巯基化合物如半胱氨酸（Cys）、高半胱氨酸（Hcy）和还原型谷胱甘肽（GSH）的加入能与TCC中的三氰基乙烯基进行加成反应从而破坏分子内电荷转移,使分子内电荷转移吸收峰消失,颜色由紫色变成黄绿色,最大吸收波长由560 nm移至380 nm。并且化合物的荧光也随着巯基化合物的加入逐渐增强,荧光的强度与巯基化合物的浓度有很好的线性关系,检测限可以达到10^-5 mol/L。其它离子与不含巯基的氨基酸则不会与化合物TCC发生上述反应,也就不会对体系的吸收和荧光光谱产生明显的影响,从而实现高效、专一的识别巯基化合物。     

Bioanalytical considerations for compounds containing free sulfhydryl groups

Thiol-containing compounds pose bioanalytical challenge in several dimensions due to extreme reactivity of the sulfhydryl group. The development of robust bioanalytical methodology for thiol groups should address the aspects of adequate stabilization in the biological matrix and selectivity considerations. In this context, availability of plethora of thiol reagents provides ample opportunity to achieve the above goals. However, several considerations need to be factored into the decision-making of a suitable scheme for the thiol drugs under investigation. This review provides some critical insights to many such considerations that may be vital for development and validation of methods for thiol-containing drugs.     

Biosensors as a tool for the antioxidant status evaluation

Antioxidants are one of the main ingredients that protect food attributes by preventing oxidation that occurs during processing, distribution and end preparation of food. Physiological antioxidant protection involves a variety of chemical system of endogenous and exogenous origin in a multiplicity of pathways. Associate to this, researches have been directed in the development of methods as biosensors that can characterize antioxidants capable of removing harmful radicals in living organisms in an adequate way. Biosensors have represented a broad area of technology useful for environmental, food monitoring, clinical applications and can represent a good alternative method to evaluate the antioxidant status.The demonstration of the highlighted current application of biosensor as a potential tool to evaluate the antioxidant status is the main aim of this review.     

Synthesis and characterization of cationic latex particles bearing sulfhydryl groups and their use in the immobilization of Fab antibody fragments (1)

Emulsion copolymerization of styrene and a cationic monomer vinylbenzyl-isothiouronium chloride (VBIC) with initiation by 2,2 azobis(2-amidinopropane)-dihydrochloride (V-50) gave monodisperse latex particles. After post-stabilization with cationic or non-ionic surfactants, the colloids were diluted in basic buffers with concomitant deprotection of the sulfhydryl groups. Therefore, coupling reactions on the latex beads were possible. Coupling conditions were determined with Ellman's reagent.¹⁴C iodoacetamide and anti C-reactive protein antibody Fab fragments were immobilized and finally, the immunological activity of the sensitized latex was assessed.     

Quantitative analysis of bucillamine in blood using high-performance liquid chromatography-mass spectrometry technique

A fast and sensitive method has been developed and validated for the determination of bucillamine in human blood by derivatizing the free sulfhydryl groups with isobutyl acrylate (IA), by APCI-LC/MS/MS. The collected blood sample was immediately mixed with a mixture of IA and 0.05 m Tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) buffer, pH 9.2, to stabilize the sulfyhydryl moieties. The derivatized samples were then extracted by protein precipitation, evaporated, reconstituted and injected using an LC-APCI/MS/MS instrument. Separation was achieved using a C18 analytical column and a gradient mobile phase within a chromatographic run time of 5 min. A quadratic (weighted 1/concentration(2)) relationship was observed during validation over a concentration range of 0.4-40 microg/mL with a correlation value of r > or = 0.9966. The inter-batch precision and accuracy at low, medium and high concentrations were 8.1, 8.4 and 7.3%; 113.3, 104.9 and 103.9%, respectively, and the intra-batch precision and accuracy at low, medium and high concentrations were 7.7, 5.4 and 2.7%; 105.1, 111.9 and 113.2%, respectively.     

Synthesis of sulfhydryl-functionalized polymers for the efficient adsorption of Pd2+ and Ag+ from aqueous solution

Herein, two sulfhydryl-functionalized polymers, namely, EDT-HCPS and TMPMP-HCPS, were synthesized according to the Friedel-Craft s alkylation and nucleophilic substitution, and they were used to adsorb Pd²⁺ and Ag⁺ from aqueous solution. The Friedel-Crafts alkylation offered the polymers with hyper-cross-linking frameworks composed of plentiful rigid methylene. The nucleophilic substitution brought abundant functional  SH groups (the sulfur contents were 12.6 and 9.4 wt%, respectively) to the polymers. The adsorption results showed that the capacities of Pd²⁺ and Ag⁺ on EDT-HCPS were larger than TMPMP-HCPS, and the higher quantities of functional  SH groups and the porosity played a beneficial role. The equilibrium data can be characterized by the Langmuir model, and the maximum capacities of Pd²⁺ and Ag⁺ on EDT-HCPS at 308 K were predicted to be 383.92 and 212.93 mg g⁻¹, respectively. The produced polymers represented superior adsorption selectivity, reproducibility, and reusability, demonstrating their excellent performance for the adsorption of Pd²⁺ and Ag⁺, and analysis of the adsorption mechanism demonstrated that the  SH groups played a major role due to the strong chemical complexation of the functional  SH with Pd²⁺/Ag⁺.     

Construction of High Expression Plasmid of Human Augmenter of Liver Regeneration （ hALR）, Expression and Purification of hALR

Introduction Theliverisoneoftheorgansthathaspotentialre generativecapabilityinmammaliananimals[1].Studies oncaninemodelshaveindicatedthatthelivercanre generate,inonlytwoweeks,toitsoriginalsize,after70%hepatectomy[2].Therefore,theresearchoncellu larandmole…