Effects Of Several Reagents Research Articles

Effect of several reagents on decolorization of methyl orange solution with KIO4

Increasing environmental pollution caused by toxic dyes due to their toxicity makes the removal of these dyes imperative. So, it is crucial to develop processes that can destroy these dyes effectively. It has been generally agreed that methyl orange (MO) solution can be effectively decolorized in KIO4 homogeneous system under UV light irradiation. The knowledge on the influence of several reagents possesses both practical and theoretical values. The effects of H2O2, K2S2O8, and KBrO3 were investigated in detail. The results of the effects of five ·OH scavengers are presented. The results show that S2O82- and BrO3- can promote the photocatalytic decolorization of MO solution and H2O2 can enhance the decolorization efficiency of MO in the dark. However, the results of the effects of five ·OH scavengers cannot substantially support the argument that the degradation mechanism of KIO4 involves hydroxyl radical attack. A more detailed mechanism needs to be further investigated in the near future.

Determination of cadmium by flow injection-chemical vapor generation-atomic absorption spectrometry.

A method was developed for the generation of a "cold vapor" of cadmium by means of flow injection-chemical vapor generation from aqueous samples, the determination being conducted with an atomic absorption spectrometer (Pyrex glass T-cell). Several gas-liquid separator designs, atomizer designs, and the effect of several reagents previously reported as sensitivity enhancers (including cobalt, nickel, thiourea and didodecyl-dimethylammonium bromide) were investigated. The limit of detection, calculated as the concentration giving a signal equal to three times the standard deviation of the blank, was 16 ng L(-1), and the relative standard deviation was 1.4% for a concentration of 2 microg L(-1) and 3.8% for 0.1 microg L(-1). The addition of nickel and thiourea to the samples provided improved tolerance to the interference of coexisting ions. Two NIST certified reference materials, Montana Soil and Apple Leaves (respectively containing 41.7+/-0.25 mg kg(-1) Cd and 0.013+/-0.002 mg kg(-1) Cd) were accurately analyzed. The interference of lead was overcome by coprecipitation with barium sulfate, and the experimental values obtained were 41+/-1 mg kg(-1) Cd and 0.013+/-0.002 mg kg(-1) Cd, respectively.

Some molecular and inhibitory specifications of a dipeptidyl carboxypeptidase from the polychaete Neanthes virens resembling angiotensin I converting enzyme.

Dipeptidyl carboxypeptidase (DCP) from the polychaete Neanthes virens, resembling mammalian angiotensin I converting enzyme (ACE), was studied to discover some of its molecular and inhibitory properties, as the first evidence of these in a marine invertebrate. Amino acid and carbohydrate contents were analyzed. The N-terminal amino acid sequence of N. virens DCP was (NH2)D-E-E-A-G-R-Q-W-L-A-E-Y-D-L-R-N-Q-T-V-L-. Peptide maps of N. virens DCP from lysyl endopeptidase digestion were different from rabbit p-ACE. The far-ultraviolet circular dichroic spectra of N. virens DCP indicated that the secondary structure of this enzyme seemed to be an alpha-helical structure and was similar to that of rabbit p-ACE, but the near-ultraviolet circular dichroic spectra of N. virens DCP indicated that the aromatic amino acid residue circumambience of this enzyme was different from rabbit p-ACE. The effects of several reagents for chemical modification of amino acids on the activity of N. virens DCP were tested. Arg, Tyr, Glu, and/or Asp, His, Trp, and Met caused loss of the activity. In addition, the IC50 and Ki values for a well-known ACE inhibitor, Val-Tyr, which was a competitive inhibitor of N. virens DCP, were 263 and 20 microM, respectively. These results suggested that N. virens DCP is different from mammalian ACE in the molecular and inhibitory properties, although the same substrate specificity was demonstrated in a previous paper.

Optimization of the reverse transcriptase assay for the detection of viral burden in mice infected with Rauscher murine leukemia virus.

Rauscher murine leukemia virus induces an erythroleukemia in susceptible strains of mice that is associated with splenomegaly and viremia. This animal model has been used for evaluating the in vivo efficacy of potential anti-HIV agents. The in vivo antiviral activity of therapeutic agents has usually been determined by measuring a reduction in the spleen weights of compound-treated mice or by quantitating viremia with the UV-XC plaque assay. The UV-XC assay, however, is time-consuming and labor-intensive. Virions of Rauscher murine leukemia virus, like other retroviruses, contain the enzyme reverse transcriptase. Quantitating the level of this enzyme in infected mouse sera provides a more rapid measure of viremia in the animal. We have examined the effects of several reagents, including detergent, KCl, EGTA, dGMP, spermine, as well as protease and RNase inhibitors, on the reverse transcriptase assay. The optimized assay method was effective in evaluating the antiviral activity of AZT in the Rauscher murine leukemia virus in vivo model. The assay is also amenable to automation if large numbers of assays are required.

Functional groups in ovine luteinizing hormone and their receptor site interactions-a chemical study.

Selective chemical reactions have long been used in the field of hormone research for the study of functional group relationships to biological activity. An early example of such a study applied to ovine LH is that of Li, Simpson and Evans (1) who employed ketene to acetylate LH (ICSH) and found that acetylation under very mild conditions inactivated the hormone. Geschwind and Li (2) found periodate oxidation inactivated ovine LH. Although in that study periodate was selected for its attack on vicinal hydroxyl groups in the carbohydrate moiety, these authors appreciated that other reactions might be taking place. In a later study from that same laboratory Gan et al. (3) demonstrated that periodate oxidation of ovine LH not only attacked the carbohydrate moiety but also the disulfide bonds in the molecule. Thus, although periodate oxidation inactivates ovine LH it is not known whether this inactivation results from destruction of the carbohydrate moieties, destruction of the disulfide bonds, or both. Our own laboratory made an extensive study of the effect of several reagents and various conditions upon the activity of ovine LH (4). Included in those studies were some on the effects of oxidation by performic acid which attacks the disulfide bonds and the thioether group of methionine. This reagent completely inactivated ovine LH. We also studied the effect of reduction with sodium and liquid ammonia on the biological activity of the hormone. Although the hormone was virtually inactivated by this treatment, it is difficult to be certain in such an experiment that there was not some reoxidation to the native hormone to account for the small residual activity observed. There are also other technical difficulties in dealing with a hormone in the reduced form at the very dilute concentrations which must be used for bioassay.

Permeability of rat liver mitochondria to leucine, tyrosine, α-aminoisobutyric acid, and lysine

Radioactive tracer studies show that l-leucine is rapidly taken up by isolated rat liver mitochondria. There is an initial rapid uptake of l-leucine during the first 30 sec of incubation, followed by a slower, progressive increase in l-leucine accumulation over a 10-min incubation. d-Leucinc penetrates the mitochondria rapidly but does not accumulate inside. Both the d and l isomers of tyrosine penetrate the mitochondria relatively more slowly, equilibration being achieved only after several minutes of incubation. The synthetic amino acid, α-aminoisobutyric acid, is shown to rapidly enter the mitochondria. This amino acid is not accumulated within the mitochondria. l-Lysine, a positively charged amino acid, exhibits uptake characteristics similar to those of l-leucine. An examination of the energetic requirements for these amino acid transfer processes reveals no dependence on metabolic energy or on gradients of inorganic cations, and no effects of several reagents known to block other transport mechanisms, under the conditions tested. These findings and previously reported observations are consistent with the view that the membranes of rat liver mitochondria contain a number of different mechanisms mediating uptake of various amino acids.

The Analysis of Data from a Designed Experiment

A statistical design for the investigation of the effects of several reagents and catalysts on production rate is used to illustrate how information additional to that planned for can be extracted from the data...

Location and composition of spore mucopeptide in Bacillus species.

Spore integuments of Bacillus coagulans were prepared containing nearly all the hexosamine and alpha, epsilon-diaminopimelic acid (DAP) present in intact spores. Subsequent autolytic action resulted in the destruction and removal of the residual cortical structure and "cortical membrane" leaving the appearance of the inner and outer spore coats unchanged in electron micrographs. Concurrently, all the hexosamine and DAP in the preparation was released mainly as non-diffusible mucopeptide containing alanine, glutamic acid, DAP, and all the glucosamine and muramic acid. Some diffusible peptides containing alanine, glutamic acid, and DAP were also present but there was little protein or carbohydrate. Lysozyme digestion of integument preparations from heated spores of Bacillus 636, B. subtilis, B. coagulans, and B. stearothermophilus specifically removed the residual cortex and cortical membrane with the release of the mucopeptide. In B. cereus T, only the residual cortex and part of the mucopeptide were solubilized by lysozyme. The effect of several reagents and enzymes upon the appearance and removal of hexosamine from B. coagul ans spore integuments is reported. The results show that spore mucopeptide is mainly located in the residual cortex and cortical membrane and suggest that these structures consist essentially of mucopeptide. The implications of these results in relation to the "contractile cortex" theory of heat resistance in spores are discussed.