Effect Of 2-mercaptoethanol Research Articles

Comprehensive elucidation of experimental results of polytype ZnS‐10H quantum dots produced in single stride

Polytypes of a material exhibit different structures (nanosheets, nanorods, nanospheres etc.), leading to distinct properties pertinent to their respective fields. Theoretical studies using computational methods have elaborated their properties and essence; however, only a few studies were presented experimentally. Ab-initio synthesis of wurtzite ZnS-10 H polytype was carried out and an extensive study was done to unfold the properties to manoeuvre in different fields. Being a potential material for quantum dot sensitized solar cells (QDSSC), ZnS-10 H was synthesized at 70 °C to enhance the properties and in conjunction with the sustainability and durability of the device. Wurtzite crystal structure of polytype ZnS-10 H was confirmed from the studies. Capping agent manifests its role by passivating the material’s surface and the efficacy of the capping agent depends on the binding affinity of ligands and the concentration of the capping agent. Photoluminescence (PL) of uncapped ZnS-10 H shows its luminescence similar to ZnS, and the effect of 2-mercaptoethanol (2-ME) is obtained with 2-ME variations, after a limit (i.e., at 6 mL of capping agent) core-shell structure formation was seen with no emission and no excitation indicating the light capturing ability. Current findings suggest the possible applications of polytype ZnS-10 H in QDSSC, photovoltaic devices and photocatalytic activities.

Synthesis and Characterization of Fe3+ and Mn2+ Doped ZnS Quantum Dots for Photocatalytic Applications: Effect of 2-Mercaptoethanol and Chitosan as Capping Agents

Fe3+ and Mn2+ capped ZnS quantum dots were synthesized using the chemical precipitation method at room temperature in aqueous media. The effect of 2-Mercaptoethanol and Chitosan as capping agents and dopants were investigated using Fourier Transform Infra-Red (FTIR), X-ray Diffraction (XRD), UV-Visible and Field Emission Scanning Electron Microscopy (FESEM) analysis of the nanocrystals. FTIR revealed the presence of respective capping agents and FESEM micrograph identifies the particles as poly-dispersed. TEM images showed agglomerated particles with crystal sized ˜3 nm. Particles were analyzed as cubic structured with peaks indexed at (1 1 1), (2 2 1) and (3 1 1) and an average crystalline size of 2.49±0.06 nm. Blue shift is obtained by both doping agents, and band gap values of ranging from 3.75–4.95 eV were reported. Characterizations suggests 2-mercaptoethanol as better capping agent compared to chitosan and has a greater potential for photocatalytic applications.

Effect of 2-mercaptoethanol as capping agent on ZnS nanoparticles: structural and optical characterization

In this work, we report the effect of a capping agent on the structural and optical properties of nanocrystalline ZnS particles, which have been synthesized by co-precipitation method. The structural properties of ZnS nanoparticles have been characterized by X-ray diffraction (XRD) analysis. The XRD patterns show a hexagonal structure in the nanoparticles. The mean crystallite size calculated from the XRD patterns has been found to be in the range of 1.80 to 2.45 nm with the increase in molar concentration of the capping agent. Absorption spectra have been obtained using a UV-vis spectrophotometer to find the optical direct band gap. We also found that optical band gap (Eg) increases with the increase in molar concentration of the capping agent. This behavior is related to size quantization effect due to the small size of the particles.

Effect of 2-mercaptoethanol on glutathione levels, cystine uptake and insulin secretion in insulin-secreting cells.

The role of glutathione (GSH) in the differentiated state of insulin-secreting cells was studied using 2-mercaptoethanol as a means of varying intracellular GSH levels. 2-Mercaptoethanol (50 microM) caused a marked increase of GSH in two rat insulinoma cell lines, RINm5F and INS-1, the latter being dependent on the presence of 2-mercaptoethanol for survival in tissue culture. The effect of 2-mercaptoethanol on GSH was shared by other thiol compounds. Since in other cell types 2-mercaptoethanol is thought to act on cystine transport, thereby increasing the supply of cysteine for GSH synthesis, we have studied [35S]cystine-uptake in INS-1 cells. At equimolar concentrations to cystine, 2-mercaptoethanol caused stimulation of [35S]cystine-uptake. The effect persisted in the absence of extracellular Na+, probably suggesting the involvement of the Xc- carrier system. INS-1 cells with a high GSH level, cultured 48 h with 2-mercaptoethanol, displayed a lower cystine uptake than control cells with a low GSH content. The effect of variations of the GSH levels on short-term insulin release was studied. No alteration of glyceraldehyde-induced or KCl-induced insulin release in RINm5F cells was detected. In contrast, both in islets and in INS-1 cells, a high GSH level was associated with a slightly lower insulin release. In INS-1 cells the effect was more marked at low glucose concentrations, resulting in an improved stimulation of insulin secretion. On the other hand, in islets, a decrease in the incremental insulin release evoked by glucose was seen. As in other cell types, oxidized glutathione (GSSG) was less than 5% of total GSH, and in INS-1 cells no change in the GSH/GSSG ratio was detected during glucose-induced or 3-isobutyl-1-methylxanthine-induced insulin release. In conclusion, 2-mercaptoethanol-dependent INS-1 cells, as well as RINm5F cells and islets of Langerhans, display a low capacity in maintaining intracellular levels of GSH in tissue culture without extracellular thiol supplementation; 2-mercaptoethanol possibly acts by promoting cyst(e)ine transport; changes in GSH levels caused a moderate effect on the differentiated function of insulin-secreting cells.

Thiol-induced fragmentation of chromosomal DNA

Supramolecular complexes of DNA (SC DNA) were isolated from loach sperm, loach erythrocytes and hen erythrocytes by the phenol method. By the use of UV-sedimentation on neutral 5-20% sucrose gradient, we studied the effect of 2-mercaptoethanol (ME), dithiothreitol (DTT) and NaBH4 on SC DNA at different pH and long-time incubation (5 and 10 days). It appeared that ME treatment at pH 4.4 fragmented SC DNA of three objects into subunits of size 5 x 10(5)D. Incubation with DTT at pH 8 in the presence of EDTA resulted in subunits of size 1-2 x 10(7)D. However, NaBH4 at pH 8 failed to induce fragmentation of SC DNA. It is shown that ME-induced at pH 4.4 fragmentation is accompanied by a decrease in hyperchromatic effect of subunits, indicating the presence of "sticky" ends. Thus, ME-induced fragmentation of SC DNA results from a "clayting" double-strand break, involving, on an average, 180 bp.

Effect of an antioxidant compound (2-mercaptoethanol) on the nerve terminals of the aging small intestine

The effect of 2-mercaptoethanol (2-ME) treatment on the nerve elements of the small intestine has been investigated in old mice. In control animals only a few synapses and a very small number of vesicles were found in the nerve terminals. Some of the nerve fibers were observed to be degenerating. After drinking 2-ME daily for 17 months, both the number of synapses and vesicles within the nerve terminals increased. No degenerated fibers wer observed. It is assumed that 2-ME has a beneficial influence on the peripheral intestinal nervous system increasing the number of synapses and the vesicle population in the nerve terminals.

Effect of 2-mercaptoethanol on some metabolic indices of ageing of CBA/Ca inbred mice

It has been shown in several studies that 2-mercaptoethanol (2-ME) improves the life span and aspects of life performance of laboratory animals. To obtain further details on the beneficial effects of 2-ME, a long-term study has been performed on male CBA/Ca inbred mice treated with this antioxidant. Four month-old mice were each given 4 μg of 2-ME in physiological saline via intraperitoneal (i.p.) injection 3 × per week. Measurements were made of the following: cold tolerance (heat performance), apparent total body protein turnover ( T 1 2 ), changes in the major lipid and fatty acid compositions of the liver, superoxide dismutase activity and formation of malondialdehyde and observations on a range of pathological changes. It was found that the basal rectal temperatures of the treated mice were higher and in the oldest group, heat performance capacity was better than those of the controls. After about 1 year of age the apparent biological half-life time of total body protein ( T 1 2 ) was observed to be shorter in the treated mice. Significant increases were observed to occur in the proportions of the polyunsaturated fatty acids in the lipids of the liver in the mice injected with 2-ME. Although no differences were observed in the superoxide dismutase activities, malondialdehyde concentrations in the livers of the experimental mice were significantly increased. Autopsy data showed that Dunn-sarcomas associated with amyloidoses occurred more frequently in the untreated mice.

The role of thiols in lymphocyte responses: Effect of 2-mercaptoethanol on interleukin 2 production

The effects of 2-ME on the production of IL 2 in mitogen-stimulated mouse splenocyte cultures were examined. Since 2-ME could conceivably affect IL 2 production and utilization equally, resulting in no apparent change in the IL 2 concentration of treated cultures, 12-h cultures were used to minimize any effects of IL 2 utilization on the IL 2 concentrations observed. Utilization of IL 2 in 12 h splenocyte cultures was estimated by means of simulations in which IL 2 from 12 h culture supernates was utilized by CTLL-2 cells comparable in number to the lymphoblasts present in splenocyte cultures. These stimulations indicate that IL 2 utilization is insignificant during the first 12 h of culture under a variety of conditions. Thus, the IL 2 concentration at 12 h reflects predominantly the rate of production. No effect was observed on IL 2 concentrations at 12 h when cultures were treated with 2-ME under conditions in which the 2-ME enhanced cellular activation/proliferation. These results indicate that 2-ME does not enhance proliferation in Con A-stimulated splenocyte cultures by increasing IL 2 production, but by some other mechanism(s).

Effect of 2-mercaptoethanol on the electrophoretic behavior of rat and dogfish metallothionein and chromatographic evidence of a naturally occurring metallothionein polymerization

1. Metallothionein behavior in SDS-PAGE has been characterized. 2. It has been found that metallothionein behavior in this electrophoretic system depends upon the reducing environment. Migration as a well-defined protein band is only achieved in the presence of 2–100 mM 2-mercaptoethanol. 3. Within those 2-mercaptoethanol levels, both rat and dogfish metallothionein migrate as a protein with a molecular weight several times higher than that expected by amino acid analyses. This is not due to molecule oxidations, since this effect is promoted by the presence of 2-mercaptoethanol. 4. No effect of 2-mercaptoethanol on metallothionein behavior is found in conventional PAGE. 5. The present results suggest that to study the effect of 2-mercaptoethanol in SDS-PAGE is a simple and accurate way to identify a protein as metallothionein. 6. It has also been found that metallothionein aggregates naturally in the absence of ionic strength.

Purification and in vitro complementation of mutant histidinol dehydrogenases.

The biochemistry of interallelic complementation within the Salmonella typhimurium hisD gene was investigated by in vitro protein complementation of mutant histidinol dehydrogenases (EC 1.1.1.23). Double-mutant strains were constructed containing the hisO1242 (constitutive overproducer) attenuator mutation and selected hisDa or hisDb mutations. Extracts from such hisDa986 and hisDb1799 mutant cells failed to show histidinol dehydrogenase activity but complemented to produce active enzyme. Inactive mutant histidinol dehydrogenases were purified from each of the two mutants by ion-exchange chromatography. Complementation by the purified mutant proteins required the presence of 2-mercaptoethanol and MnCl2, and protein-protein titrations indicated that heterodimers were strongly preferred in mixtures of the complementary mutant enzymes. Neither mutant protein showed negative complementation with wild-type enzyme. The Vmax for hybrid histidinol dehydrogenase was 11% of that for native enzyme, with only minor changes in Km values for substrate or coenzyme. Both purified mutant proteins failed to catalyze NAD-NADH exchange reactions reflective of the first catalytic step of the two-step reaction. The inactive enzymes bound 54Mn2+ weakly or not at all in the presence of 2-mercaptoethanol, in contrast to wild-type enzyme which bound 54Mn2+ to 0.6 sites per monomer under the same conditions. The mutant proteins, like wild-type histidinol dehydrogenase, behaved as dimers on analytical gel filtration chromatography, but dissociated to form monomers in the presence of 2-mercaptoethanol. This effect of 2-mercaptoethanol was prevented by low levels of MnCl2. It thus appears that mutant histidinol dehydrogenase molecules bind metal ion poorly. The complementation procedure may allow for formation of a functional Mn2+-binding site, perhaps at the subunit interface.

Inhibition of sarcoplasmic reticulum Ca 2+-ATPase by 2-mercaptoethanol

The Ca 2+-dependent ATPase activity of sarcoplasmic reticulum was inhibited when membrane vesicles were incubated at 0°C in presence of thiols. 2-mercaptoethanol was the most effective inhibitor from the thiols tested. The effect of 2-mercaptoethanol on the ATPase activity was biphasic; enzyme inhibition originally increased and then decreased with increasing thiol concentration. The inhibitory action of this thiol was significantly higher at low membrane concentrations and the rate of inactivation at 22°C was considerably lower than that at 0°C. Ca 2+-ATPase previously inhibited by 2-mercaptoethanol was partially reactivated by incubation with periodate.

High concentrations of oxygen modulate in vitro Con A responses of rat lymphoid cells. Effect of 2-mercaptoethanol

The effects of different normobaric oxygen concentrations (40, 60 and 95%) on the survival and the proliferative response to Con A of rat lymphoid cells were studied. Spleen, thymus and peripheral blood mononuclear cells were tested. We found that oxygen concentrations modulated the proliferative response independently of cell survival. The addition of 2-mercaptoethanol (2-ME) partially prevented the toxic effects of hyperoxia but the population of thymocytes which responded to Con A stimulation appeared to be less sensitive to the protective action of 2-ME. The relationship between oxygen concentrations and the lymphoid proliferative response could be used as a model of oxidant immunodepression for evaluating pharmacological effects of antioxidant compounds.

Effect of 2-mercaptoethanol on the electrodeposition of lead

The morphology and the electro-kinetic parameters of lead electrodeposits on polycrystalline lead have been studied in a fluoborate bath at several current densities in the presence of known concentrations of 2-mercaptoethanol. It was observed that there was a notable decrease in the grain-size at low concentrations of the addition agent and the critical concentration varied with the current density. The growth habit modification and the changes in the kinetic parameters with increasing concentrations of the addition agent and current density, were investigated. Suitable transport mechanisms were proposed with the help of IR and X-ray studies.

Mitogen response of peripheral blood and splenic lymphocytes and effect of 2-mercaptoethanol in tumor-bearing mice

A murine osteosarcoma in which the number of tumor cells can be continually monitored by measuring the circulating plasma alkaline phosphatase levels was used to determine the effect of tumor burden on peripheral blood and splenic lymphocyte response to mitogens. In animals with tumors of different sizes, the pattern of response of the peripheral blood lymphocytes (PBL) to mitogens is different from that of splenic lymphocytes. PBL response to ConA, PHA, and LPS was initially depressed, but response to PHA and LPS recovered later, as the tumor burden exceeded 6%. However, the recovery of LPS response was not consistent, in that recovery was not seen when the tumor burden was 5%–6%. Response to ConA remained depressed. Splenic lymphocytes showed progressive decline of PHA response. Treatment of tumor-bearing mice with 2-mercaptoethanol (2-ME) restored the ConA response of PBL in 56% of mice. Treatment with 2-ME did not restore PBL response to PHA or LPS.

Effect of 2-mercaptoethanol on the haemagglutinating activity and antigenic properties of rubella virus

Tween-ether treated rubella virus extract treated with 2-mercaptoethanol no longer haemagglutinates and its ability to combine with antibody is reduced although its sedimentation characteristics and the electrophoretic mobilities of the envelope glycoproteins are unaffected. The role of disulphide bonds in maintaining the structural and functional integrity of rubella virus is discussed.

The effect of 2-mercaptoethanol on IgM and IgG antibody activity

The effect of reduction by 2-mercaptoethanol (2-ME) on antibody activity was studied in antisera with high anf low IgG concentrations. Sera obtained from B10.LP nu/nu mice during a primary response against a rat PVG/c skin graft contained only 2-ME sensitive antibodies. However, when analyzed on sucrose gradients, IgG as well as IgM antibody activity was present. After raising the low serum IgG concentration (0.3–0.7 mg/ml) of these sera by additional of normal mouse serum (5.1 mg IgG/ml), 2-ME resistant antibodies became detactable. Hyperimmune C57BL6 anti PVG/c lymphocyte serum with a high IgG concentration (20.2 mg/ml) and antibody activity predominatly located in the IgG class was not affected by 2-ME treatment. These data show that IgG antibodies, although less susceptible to reduction than IgM antibodies, are not resistant to this treatment. At high IgG concentrations the proportion of inactivated IgG with specific antibody will be negligible but a low IgG concentrations the use of this method leads to serious underestimation of IgG antibody activity.

B and T lymphocyte colony formation in agar: 2-Mercaptoethanol-activated albumin can substitute for 2-mercaptoethanol

The effect of 2-mercaptoethanol (2-ME) activated albumin (MaSF) on mouse B lymphocyte colony (BLC) formation and on human phytohemagglutinin (PHA)-induced T lymphocyte colony formation (TLC) formation in semisolid agar medium was studied. MaSF was found to stimulate colony formation comparable to the stimulation obtained with 2-ME. MaSF could not substitute for serum in any of the agar culture systems. BLC formation stimulated by MaSF was obtained with spleen cells from athymic nude mice and nonadherent spleen and lymph node cells of normal mice suggesting a direct effect of MaSF on the colony-forming B cell without interference with T cells or macrophages. The results suggest that the stimulatory effect of 2-ME in the BLC and TLC agar systems is mediated by 2-ME-activated albumin present in the culture medium.

Metabolism of 1,2-propanediol by methanol-utilizing bacteria and some properties of 1,2-propanediol dehydrogenating enzyme.

Methanol-utilizing bacteria, Klebsiella sp. No. 101 and Microcyclus eburneus could grow aerobically and statically on 1,2-propanediol. The authors examined the presence of enzyme activity of adenosyl-B12 dependent diol dehydratase as well as NAD dependent diol dehydroagenase. Adenosyl-B12 dependent diol dehydratase activity was not detected in these organisms, even if these grown statically.The dehydrogenase activity was found in the extract from these methanol-utilizing bacteria cells grown on various carbon sources. The partially purified enzyme preparation from the cells of Mic. eburneus grown aerobically on 1,2-propanediol dehydrogenated 1,2-propanediol, 1,2-butanediol and 2,3-butanediol. The enzyme activity was separated into two fractions, namely enzyme I and II on DEAE-Sephadex A-25 column chromatography. The enzyme I was different from the enzyme II in the ratio of enzyme activity to 1,2-propanediol and 2,3-butanediol, heat stability, pH stability and pH optimum, and effect of 2-mercaptoethanol.

Nonspecific activation of murine lymphocytes. I. Proliferation and polyclonal activation induced by 2-mercaptoethanol and alpha-thioglycerol.

The effect of 2-mercaptoethanol (2-ME) and alpha-thioglycerol (alpha TG) on proliferation and polyclonal activation of lymphocytes was studied in cultures of spleen cells from C3H mice. Inclusion in serum-free or serum-containing medium of the optimal concentration (5 x 10(-5) M) of either 2-ME or alpha TG resulted in highly significant uptake and incorporation of tritiated thymidine ([3H]TdR) into DNA and in morphological blast transformation. These phenomena were dose-dependent, with both lower and higher doses causing less marked effects. The kinetic peak of these responses was found to occur at day 3 of culture. Improved cellular viability could not explain these results, because by day 3 there was no significant difference in viability between cells cultured in the presence or absence of 2-ME. 2-ME evoked a proliferative response in cultures of congenitally athymic (nu/nu) spleen cells that exhibited a similar but lower dose-response profile compared with that of heterozygous (nu/+) littermates. Cultures of bone marrow-derived (B) lymphocytes, generated by treatment of spleen cells with rabbit antithymocyte serum and complement, incorporated [3H]TdR to a degree at least equal to that of normal spleen cell cultures. Thymus-dependent (T) cells did not support significant 2-ME, alpha TG, or Concanavalin A responses in the absence of serum. However, when cultured in 5% fetal calf serum, definite T-cell responses occurred, though always of a lower magnitude than B-cell responses in this system. When the enriched B-cell and T-cell preparations were co-cultured, a synergistic response was noted. Macrophage dependency of the 2-ME and alpha TG effect was shown to be minimal. It is likely that the greater effectiveness of alpha TG relative to 2-ME is due to differences in the chemical structure of these two thiol compounds. The advantages of utilizing 2-ME and alpha TG as probes in the study of lymphocyte activation are evaluated and their possible mechanisms of action are discussed.

Differential stimulation of murine lymphoma growth in vitro by normal and BCG-activated macrophages.

Peritoneal macrophages from mice infected with Bacille Calmette-Guérin (BCG) and from normal mice were examined for their effects in vitro on thymidine uptake by 10 murine lymphomas, a murine fibroblast line, and a guinea pig hepatoma. Only the murine fibroblast line showed growth inhibition in the presence of BCG macrophages. For the majority of tumors, normal macrophages were profoundly stimulatory to tumor cell DNA synthesis, while BCG macrophages were much less stimulatory, without being frankly inhibitory. The effect of 2-mercaptoethanol on tumor cell growth was also studied. All lymphomas stimulated to grow more rapidly in vitro by normal macrophages were stimulated to a similar degree by 2-mercaptoethanol.