Cysteic Acid Research Articles

Effect of oxidative stress on cystine transportation by xC‾ antiporter

We performed computer simulations to investigate the effect of oxidation on the extracellular cystine (CYC) uptake by the xC− antiporter. The latter is important for killing of cancer cells. Specifically, applying molecular dynamics (MD) simulations we studied the transport of CYC across xCT, i.e., the light subunit of the xC− antiporter, in charge of bidirectional transport of CYC and glutamate. We considered the outward facing (OF) configuration of xCT, and to study the effect of oxidation, we modified the Cys327 residue, located in the vicinity of the extracellular milieu, to cysteic acid (CYO327).Our computational results showed that oxidation of Cys327 results in a free energy barrier for CYC translocation, thereby blocking the access of CYC to the substrate binding site of the OF system. The formation of the energy barrier was found to be due to the conformational changes in the channel. Analysis of the MD trajectories revealed that the reorganization of the side chains of the Tyr244 and CYO327 residues play a critical role in the OF channel blocking. Indeed, the calculated distance between Tyr244 and either Cys327 or CYO327 showed a narrowing of the channel after oxidation. The obtained free energy barrier for CYC translocation was found to be 33.9kJmol−1, indicating that oxidation of Cys327, by e.g., cold atmospheric plasma, is more effective in inhibiting the xC− antiporter than in the mutation of this amino acid to Ala (yielding a barrier of 32.4kJmol−1). The inhibition of the xC− antiporter may lead to Cys starvation in some cancer cells, eventually resulting in cancer cell death.

Antisickling Drugs Targeting βCys93 Reduce Iron Oxidation and Oxidative Changes in Sickle Cell Hemoglobin.

Sickle cell disease is a genetic blood disorder caused by a single point mutation in the β globin gene where glutamic acid is replaced by valine at the sixth position of the β chain of hemoglobin (Hb). At low oxygen tension, the polymerization of deoxyHbS into fibers occurs in red blood cells (RBCs) leading to an impaired blood vessel transit. Sickle cell hemoglobin (HbS), when oxidized with hydrogen peroxide (H2O2), stays longer in a highly oxidizing ferryl (Fe4+) form causing irreversible oxidation of βCys93 to a destabilizing cysteic acid. We have previously reported that an antisickling drug can be designed to bind specifically to βCys93 and effectively protect against its irreversible oxidation by H2O2. Here, we report oxygen dissociation, oxidation, and polymerization kinetic reactions for four antisickling drugs (under different preclinical/clinical developmental stages) that either site-specifically target βCys93 or other sites on the HbS molecule. Molecules that specifically bind to or modify βCys93, such as 4,4′-di(1,2,3-triazolyl) disulfide (TD-3) and hydroxyurea (HU) were contrasted with molecules that target other sites on Hb including 5-hydroxymethyl-2-furfural (5-HMF) and L-glutamine. All reagents induced a left shift in the oxygen dissociation curve (ODC) except L-glutamine. In the presence of H2O2 (2.5:1, H2O2:heme), both TD-3 and HU reduced the ferryl heme by 22 and 37%, respectively, which corresponded to a 3- to 2-fold reduction in the levels of βCys93 oxidation as verified by mass spectrometry. Increases in the delay times prior to polymerization of HbS under hypoxia were in the following order: TD-3 > HU > 5-HMF = L-glutamine. Designing antisickling agents that can specifically target βCys93 may provide a dual antioxidant and antisickling therapeutic benefits in treating this disease.

Tissue content of thiol-containing amino acids predicts methylmercury in aquatic invertebrates

Aquatic invertebrates vary in methylmercury (MeHg) levels among systems which has been attributed, in part, to environmental conditions, but may also be linked to differences in their biochemical composition. As MeHg is known to bind to thiol-containing amino acids such as cysteine in proteins of fish, our objective was to determine if these amino acids explain MeHg variability among aquatic invertebrate taxa. Benthic macroinvertebrates from diverse functional feeding groups and bulk zooplankton were collected from six acidic lakes in Kejimkujik National Park, Nova Scotia, Canada, and analyzed for MeHg, cysteine (as cysteic acid), methionine (as methionine sulfone), and nitrogen (relative trophic level, δ15N) and carbon (carbon source, δ13C) isotopes. MeHg was significantly and positively related to cysteine or methionine in zooplankton, caddisfly and stonefly tissues (R2 from 0.24 to 0.57). In addition, methionine or cysteine in combination with δ15N and/or δ13C were better predictors of MeHg levels in stoneflies, mayflies, caddisflies and zooplankton among these lakes (R2adj = 0.25–0.91). Overall, these novel findings suggest that the variability in MeHg of aquatic invertebrates can be explained, in part, by their tissue levels of thiol-containing amino acids.

Sulfonated Nonpolymeric Aminophosphonate Scale Inhibitors—Improving the Compatibility and Biodegradability

Phosphonate-based scale inhibitors are widely used in the upstream oil and gas industry, but many of them lack good compatibility with high calcium brines. Here, we report the synthesis of several nonpolymeric aminobismethylenephosphonates with an added sulfonate group to improve the compatibility. The chemicals are 2-(bis(phosphonomethyl)amino)alkane-1-sulfonic acid (alkane = methane, ethane, and propane labeled SI-1 to SI-3, respectively), N,N-bis(phosphonomethyl)cysteic acid (SI-4), and N,N-bis(phosphonomethyl) metanilic acid (SI-5). To screen their performance, we carried out dynamic scale loop inhibition performance tests for calcium carbonate and barium sulfate, thermal stability tests, and calcium compatibility tests up to 10 000 ppm calcium ions and compared them to some well-known oilfield scale inhibitors. Seawater biodegradation over 28 days (BOD28) was also investigated by the OECD 306 method. All new inhibitors demonstrated good calcite inhibition properties, but only SI-1 and SI-2 gave fairly good barite inhibition. SI-2 stood out as an excellent calcite inhibitor, suitable for use in very high calcium-containing brines. SI-2 could also provide protection against barite deposition under mild to medium scaling potentials and gave a reasonable rate of biodegradation (BOD28 = 46%). SI-1 and SI-4 gave BOD28 values of 79 and 84%, respectively, and can be classed as “readily biodegradable”. Of the two products, SI-1 seems the most promising for further studies given the better calcite and barite scale inhibition properties. Of the SIs tested, SI-5 showed the best thermal stability at 130 °C and could therefore be a useful downhole squeeze SI for fairly high-temperature wells. Its BOD28 value was 41%. Overall, the study highlights the difficulty of designing a scale inhibitor with all of the major features required for application over a wide range of field conditions.

Identifying Reducing and Capping Sites of Protein-Encapsulated Gold Nanoclusters.

The reducing and capping sites along with their local structure impact photo properties of the red bovine serum albumin-capped Au nanocluster (BSA-AuNC), however, they are hard to identify. We developped a workflow and relevant techniques using mass spectrometry (MS) to identify the reducing and capping sites of BSA-AuNCs involved in their formation and fluorescence. Digestion without disulfide cleavages yielded an Au core fraction exhibiting red fluorescence and [AunSm] ion signals and a non-core fraction exhibiting neither of them. The core fraction was identified to mainly be comprised of peptides containing cysteine residues. The fluorescence and [AunSm] signals were quenched by tris(2-carboxyethyl)phosphine, confirming that disulfide groups were required for nanocluster stabilization and fluorescence. By MS sequencing, the disulfide pairs, C75–C91/C90–C101 in domain IA, C315–C360/C359–C368 in domain IIB, and C513–C558/C557–C566 in domain IIIB, were identified to be main capping sites of red AuNCs. Peptides containing oxidized cysteines (sulfinic or cysteic acid) were identified as reducing sites mainly in the non-core fraction, suggesting that disulfide cleavages by oxidization and conformational changes contributed to the subsequent growth of nanoclusters at nearby intact disulfide pairs. This is the first report on precise identification of the reducing and capping sites of BSA-AuNCs.

Free amino acid concentration in serum and trapezius muscle from male and female silver foxes (Vulpes vulpes)

Serum and muscle concentrations of 29 amino acids were determined in Silver fox. Serum concentrations of proline, alanine, tyrosine and aromatic amino acids were significantly higher in males than in females (all P = 0.05). Taurine and glycine concentrations in skeletal muscles were significantly higher in males than in females (P < 0.01). Muscle concentrations of cysteic acid, taurine, aspartate, threonine, serine, glycine, alanine, citruline, valine, leucine, gamma-amino-butyrate, ethanoloamine, lysine and histidine were significantly higher than in serum in both sexes (P < 0.05). In females, the concentrations of glutamate, glutamine, cystathionine, isoleucine, tyrosine, phenylalanine, arginine and amino-adipic acid were significantly higher in muscles than in serum (P < 0.05). Tryptophan concentration was significantly higher in serum from males than in muscles (P = 0.01). The concentration of branched-chain amino acids in skeletal muscles was approximately two times higher than in serum in both groups of foxes (P ≤ 0.01). Similar differences were obtained for aromatic amino acids in females (P = 0.04). The elaborated experimental model may serve for further studies focused on amino acid metabolism regulation in Canide and other monogastric mammals, especially with the use of environmental, dietary, pharmacological and toxicological factors. The elaborated experimental model may be an attractive alternative to replace some experiments on dogs.

Substitutions in the β subunits of sickle-cell hemoglobin improve oxidative stability and increase the delay time of sickle-cell fiber formation

After reacting with hydrogen peroxide (H2O2), sickle-cell hemoglobin (HbS, βE6V) remains longer in a highly oxidizing ferryl form (HbFe4+=O) and induces irreversible oxidation of “hot-spot” amino acids, including βCys-93. To control the damaging ferryl heme, here we constructed three HbS variants. The first contained a redox-active Tyr in β subunits (F41Y), a substitution present in Hb Mequon; the second contained the Asp (K82D) found in the β cleft of Hb Providence; and the third had both of these β substitutions. Both the single Tyr-41 and Asp-82 constructs lowered the oxygen affinity of HbS but had little or no effects on autoxidation or heme loss kinetics. In the presence of H2O2, both rHbS βF41Y and βF41Y/K82D enhanced ferryl Hb reduction by providing a pathway for electrons to reduce the heme via the Tyr-41 side chain. MS analysis of βCys-93 revealed moderate inhibition of thiol oxidation in the HbS single F41Y variant and dramatic 3- to 8-fold inhibition of cysteic acid formation in rHbS βK82D and βF41Y/K82D, respectively. Under hypoxia, βK82D and βF41Y/K82D HbS substitutions increased the delay time by ∼250 and 600 s before the onset of polymerization compared with the rHbS control and rHbS βF41Y, respectively. Moreover, at 60 °C, rHbS βK82D exhibited superior structural stability. Asp-82 also enhanced the function of Tyr as a redox-active amino acid in the rHbS βF41Y/K82D variant. We conclude that the βK82D and βF41Y substitutions add significant resistance to oxidative stress and anti-sickling properties to HbS and therefore could be potential genome-editing targets.

Simultaneous determination of l‑DOPA, l‑tyrosine and uric acid by cysteic acid - modified glassy carbon electrode

Electrochemical oxidation of l‑cysteine resulted in the formation of a film on glassy carbon electrode. In a solution of levodopa (l‑DOPA), l‑tyrosine (Tyr) and uric acid (UA), three separated intense anodic peaks were appeared in differential pulse voltammetry regime. Experimental conditions were optimized for simultaneous determination of the three compounds. All experiments were carried out in phosphate buffer solution (0.1 M, pH 8). Calibration curves were obtained in the presence of various concentrations of l‑DOPA, Tyr, and UA. Linear concentration ranges were 0.65–22 μM for l‑DOPA, 3.5–96 μM for Tyr, and 1.0–19 μM for UA. The limits of detection (LODs) were calculated as 0.2, 1.1 and 0.36 μM for l‑DOPA, Tyr, and UA, respectively. The electrochemical sensor was used successfully for the simultaneous determination of l‑DOPA, Tyr, and UA species in human blood serum samples.

Методи екстракції кератинів із вовни та волосся і перспективи їхнього застосування в біомедицині й біоінженерії

The present article gives the overview of scientific information on the hair structure, the structural and functional properties of keratins, and methods of their extracting from the natural fibers. The article substantiates an importance of keratin extraction by breaking the disulfide bonds and converting the keratin into a soluble form while maintaining covalent bonds. Such extraction preserves the native properties of these proteins, that ensures their further use as functional biomaterials. The examples of such properties are: resistance of keratin to the effects of chemical and biological factors (due to high frequency of disulfide bonds that make a large number of chemical modifications of proteins possible) and high biocompatibility and low cytotoxicity of keratin-based preparations (due to a similarity of keratin to the extracellular matrix of biological tissues). The keratin-based materials, obtained by this way and then lyophilized, can form fibrillar structures when a particular solvent is selected. The methods of keratins extraction, as well as the efficiency and electrophoretic profiles of obtained extracts, were also analyzed. The purposeful extraction is carried out by the methods based on oxidation, reduction, and sulfitolysis reactions. The oxidation reactions of keratin are irreversible and cause the oxidation of cysteine residues to cysteic acid with the formation of keratosis. At the same time, keratin is obtained due to a reduction reactions. As a result of the reversible process of sulfitolysis, the S-sulfonate anion is formed. The paper also considers promising applications of extracted keratin in biomedicine and bioengineering. The biomedical technologies are related to the effective treatment of hair pathologies. The second area is the creation of keratin-based biomaterials with a wide range of applications, such as tissue engineering, reparative medicine, textile industry, agriculture, cosmetology, and production of cleaning equipment. The third area of keratins application is the identification of a person. Such application makes an important contribution to the anthropological research and forensic science. High resistance of hair proteins to adverse environmental conditions makes this area very promising. Keywords: hair, keratins, extraction

Why Natural or Electron Irradiated Sheep Wool Show Anomalous Sorption of Higher Concentrations of Copper(II).

Sorption of higher concentrations of Cu(II) solution onto natural sheep wool or wool irradiated by an electron beam was studied. Sorption isotherms were of unexpected character, showing extremes. The samples with lower absorbed doses adsorbed less than non-irradiated wool, while higher doses led to increased sorption varying with both concentration and dose. FTIR spectra taken from the fibre surface and bulk were different. It was concluded that there was formation of Cu(II)-complexes of carboxylic and cysteic acids with ligands coming from various keratin macromolecules. Clusters of chains crosslinked through the ligands on the surface limit diffusion of Cu(II) into the bulk of fibre, thus decreasing the sorption. After exhausting the available ligands on the surface the remaining Cu(II) cations diffuse into the keratin bulk. Here, depending on accessibility of suitable ligands, Cu(II) creates simple or complex salts giving rise to the sorption extremes. Suggestion of a mechanism for this phenomenon is presented.

The physical and chemical disruption of human hair after bleaching - studies by transmission electron microscopy and redox proteomics.

To understand the structural and chemical effects of cosmetic peroxide bleaching on human hair. Human hair was progressively bleached using alkaline peroxide-persulphate treatment. Proteins lost through leaching were examined using amino acid analysis and mass spectrometric sequencing. Fibre damage was assessed using transmission electron microscopy, amino acid analysis and redox proteomics. Protein loss through leaching increased with bleaching severity. Leached proteins were not limited to the cuticle, but also included cortical intermediate filaments and matrix keratin-associated proteins. The leached proteins were progressively oxidized as bleaching severity increased. Bleached fibres demonstrated substantial damage to the cuticle layers and to the cortex. Extensive melanin granule degradation was present after the mildest bleach treatment. Protein oxidation in bleached fibres was principally in cortical intermediate filaments - the most abundant hair proteins - and targeted the sulphur-containing amino acids, particularly the conversion of cystine disulphide bonds to cysteic acid. Peroxide chemical treatments quickly access the cortex, causing untargeted oxidative damage across the fibre in addition to the desired loss of melanin. Peroxide ingress is likely facilitated by the considerable structural degradation caused to the cuticle layers of hair fibres. The consequences of the peroxide action within the cuticle and cortex are oxidation of the proteins, and subsequent protein loss from the fibre that correlates to bleaching severity.

Identification of a crucial amino acid responsible for the loss of specifying FGFR1-KLB affinity of the iodinated FGF21.

Previous studies suggest that specific binding to the complex consisting of fibroblast growth factor receptor-1 (FGFR1) and the coreceptor beta-Klotho (KLB) is the premise for human FGF19 and FGF21 activating the downstream signaling cascades, and regulating the metabolic homeostasis. However, it was found that human FGF21 loses its ability to bind to FGFR1-KLB after iodination with Na125 I and chloramine T, whereas human FGF19 retained its affinity for FGFR1-KLB even after iodination. The molecular mechanisms underlying these differences remained elusive. In this study, we first demonstrated that an intramolecular disulfide bond was formed between cysteine-102 and cysteine-121 in FGF21, implying that the oxidation of the cysteine to cysteic acid, which may interfere with the active conformation of FGF21, did not occur during the iodination procedures, and thus ruled out the possibility of the two conserved cysteine residues mediating the loss of FGF21 binding affinity to FGFR1-KLB upon iodination. Site-directed mutagenesis and molecular modeling were further applied to determine the residue(s) responsible for the loss of FGFR1-KLB affinity. The results showed that mutation of a single tyrosine-207, but not the other five tyrosine residues in FGF21, to a phenylalanine retained the FGFR1-KLB affinity of FGF21 even after iodination, whereas replacing the corresponding phenylalanine residue with tyrosine in FGF19 did not alter its binding affinity to FGFR1-KLB, but decreased the receptor binding ability of the iodinated protein, suggesting that tyrosine-207 is the crucial amino acid responsible for the loss of specifying FGFR1-KLB affinity of the iodinated FGF21.

Studies on the interaction of aquacobalamin with cysteinesulfinic and cysteic acids, hypotaurine and taurine

abstractThis study reports results of kinetic and mechanistic studies on the reactions of aquacobalamin (H2OCbl+) with oxo-derivatives of cysteine, that is, cysteinesulfinic and cysteic acids, hypotaurine and taurine. The reactions with cysteinesulfinic acid and hypotaurine result in formation of S-bound complexes, whereas cysteic acid and taurine are coordinated with aquacobalamin via amino-group. Reaction of taurine with H2OCbl+ produces a substantially more stable complex than with cysteic acid, whereas the affinity of cysteinesulfinic acid toward aquacobalamin is slightly higher than that of hypotaurine.

Hair Loss Management

95% of hair loss in men is caused by Androgenetic Alopecia. Major causes of hair loss are Stress, Pollution, Lack of nutrition, Illness, Alcohol, Smoking, Effluvium. For hair loss should we take oral drugs or apply topically on hair? It’s a big question for all of us. Before discussion we need to know the Hair Constituents: Human hair consists of approximately 65 % to 95 %protein. Besides cystine, human hair cuticle contains cysteic acid, proline, thereonine, isoleucine, methionine, leucine, tyrosine, phenylalanine in quite high proportion. The remaining constituents are water, lipid, pigment & trace elements that are not free but bound with protein or fatty acids side chain. So…? Consumed food products should contain; PROTEIN, LIPID, WATER and TRACE ELEMENTS. For direct impact on structure, growth and keeping hair shiny and healthy. Standard value proteins containing Sulphur amino acids: Cysteine & Methionine as precursor to keratin hair protein Synthesis are basic element of diet conditioning of hair building.

Catalytic effect of different reactor materials under subcritical water conditions: decarboxylation of cysteic acid into taurine

In order to understand the influence of reactor materials on the catalytic effect for a particular reaction, the decomposition of cysteic acid from Ni/Fe-based alloy reactors under subcritical water conditions was examined. Experiments were carried out in three batch reactors made of Inconel 625, Hastelloy C-22 and SUS 316 over temperatures of 200 to 300 °C. The highest amount of eluted metals was found for SUS 316. The results demonstrated that reactor materials contribute to the resulting product. Under the tested conditions, cysteic acid decomposes readily with SUS 316. However, the Ni-based materials (Inconel 625 and Hastelloy C-22) show better resistance to metal elution. It was found that among the materials used in this work, SUS 316 gave the highest reaction rate constant of 0.1934 s−1. The same results were obtained at temperatures of 260 and 300 °C. Investigation of the Arrhenius activation energy revealed that the highest activation energy was for Hastelloy C-22 (109 kJ/mol), followed by Inconel 625 (90 kJ/mol) and SUS 316 (70 kJ/mol). The decomposition rate of cysteic acid was found to follow the results for the trend of the eluted metals. Therefore, it can be concluded that the decomposition of cysteic acid was catalyzed by the elution of heavy metals from the surface of the reactor. The highest amount of taurine from the decarboxylation of cysteic acid was obtained from SUS 316.

Identification of metabolic pathway disturbances using multimodal metabolomics in autistic disorders in a Middle Eastern population

We analyzed for the first time the metabolic profile of Lebanese children affected by autistic disorders to compare this profile to other metabolomics studies and to identify the associated metabolic disturbances. Urine samples of 40 patients with Autism spectrum disorder (ASD) and 40 healthy matched controls were analyzed using nuclear magnetic resonance (NMR) and liquid chromatography coupled to high-resolution mass spectrometry (LC–MS). Multivariate analysis on analytical data fusion was conducted on the training set of 50 urine samples, and then validated with a test set of 30 samples, this repeated 10 times. The model was also evaluated using a receiver operating characteristic curve showing a specificity and a sensitivity of 86% and 80%, respectively. Among the most significant metabolites that contributed to the discrimination between ASD and controls, we confirmed the perturbations of tyrosine, 2-hydroxybutyrate, creatine and glutamate. We found new metabolites such as trigonelline, cysteic acid and guanine. We found metabolic perturbations including amino acids, carbohydrates and oxidative stress pathways which added value for the contribution of known metabolic disturbances in ASD observed in populations of other ethnic and geographic origins.

Sheep wool-derived hydrolyzed keratin from tannery waste of the tanning industry using perhydrol

Sheep wool waste discharged from leather tanning industry recently has posed a problem in relation to its treatment because of its sizeable quantity and its difficulty to degrade. Wool is composed mainly of keratin. It is a protein with a high content of disulfide bonds which cause the protein keratin cannot dissolve in water and resist of diluted acids and alkalis. Keratin can be hydrolyzed to produce keratin hydrolysates which have many benefits such as for cosmetic additives. Research into the use of waste wool of sheep originated from the sheep leather tanning industry had been performed by using a hydrolyzed system to produce protein keratin. The waste wool used came from unhairing by painting and conventional unhairing. Hydrolysis was done using hydrogen peroxide 50% amounting to 70 ml for every 40 gr of wool. Hydrogen peroxide was added to wool immersed in the 0.5 M NaOH solution for three hours. The length of hydrolysis ranged from 4, 5, to 6 hours and the mix was stirred shortly every 1 hour followed by filtration using a coarse sieve. To precipitate the hydrolyzed keratin, the pH was decreased to 4-5 using the 2 M HCl solution and after separation of the precipitation, it was dried in the oven at a temperature not more than 50 oC for 2 days. The research findings showed that a maximum of 69.19% of keratin hydrolysates was generated using the raw material of waste wool through a conventional process with a total of hydrolysis time by 6 hours, whereas the maximum protein generated was 66.99% using waste wool through a conventional process with a total of hydrolysis time by 4 hours. The FTIR test showed the presence of groups of amides, cysteic acids, and cystine-S-monoxide.

Simultaneous analysis of free amino acids and taurine-related compounds in deep-sea mussel tissues using reversed-phase HPLC

Taurine and hypotaurine are abundantly present in molluskan tissues; however, the pathways for their biosynthesis have not yet been well investigated. In this study, we established a method for simultaneous detection of taurine-related compounds, including taurine, hypotaurine, cysteic acid, cysteine sulfinic acid (CSA), cystathionine, γ-aminobutyric acid, and β-alanine along with 17 free amino acids, using phenylthiocarbamyl derivatization in ammonia-containing solution, followed by injection into reversed-phase high-performance liquid chromatography. Using this method, we analyzed the major tissues (gill, mantle, adductor muscle, foot, and digestive gland) of the hydrothermal-vent-specific mussel Bathymodiolus septemdierum. The gill and digestive gland were suggested to be the major organs for taurine/hypotaurine biosynthesis because taurine and hypotaurine levels tended to be high, and their precursors, i.e., cysteine, cysteic acid, and CSA (only in digestive gland), were detected in these two tissues. Cystathionine was detected at relatively high level in digestive gland and in other tissues at low levels, suggesting its role as storage material for taurine/hypotaurine biosynthesis. Adductor muscle was found to be rich in free amino acids, mainly due to abundance of non-sulfur-containing amino acids.

Quantification of sulphur amino acids by ultra-high performance liquid chromatography in aquatic invertebrates

We examined the performance of an ultra-high performance liquid chromatography method to quantify protein-bound sulphur amino acids in zooplankton. Both cysteic acid and methionine sulfone were linear from 5 to 250 pmol (r2 = 0.99), with a method detection limit of 13 pmol and 9 pmol, respectively. Although there was no matrix effect on linearity, adjacent peaks and co-eluting noise from the invertebrate proteins increased the detection limits when compared to common standards. Overall, performance characteristics were reproducible and accurate, and provide a means for quantifying sulphur amino acids in aquatic invertebrates, an understudied group.

Electron beam irradiated sheep wool – Prospective sorbent for heavy metals in wastewater

Sheep wool water-washed in ultrasonic bath and slightly pre-dried was irradiated by accelerated electron beam applying dose of (0–350) kGy. The samples underwent sorption examination with Cr(III), Cd(II) and Pb(II). Sorption of Cr(III) by the irradiated wool investigated at unified concentration of 24 mmol dm−3 for each absorbed dose showed intensive increase of Cr(III) sorption up to 3.13 × against the non-irradiated sample. It is concluded that some residual humidity in irradiated wool, being a rich oxygen source, enhances sorption due to faster cysteic acid formation. Sorption experiments with Cr(III), Cd(II) and Pb(II) ions of lower concentration up to 1.4 mmol dm−3 individually indicated equal sorption as for non-irradiated wool up to 0.4 mmol dm−3. Beyond this concentration the sorption for the non-irradiated wool was lower compared with irradiated wool for any dose. The sorption increase depending on dose was different for particular doses. The order of the sorption in mg ion/1 g wool is in conformity with published data and correlates with size of the ionic radii (Pb(II) > Cd(II) > Cr(III)).