Acid In Question Research Articles

BORON-NITROGEN COMPOUNDS IN THE REACTION OF BORIC AND BORONIC ACIDS WITH AMINES

The article is a review of boric or arylboronic acids reactions with aliphatic and aromatic amines. The review is for informational purposes only on the interaction of the acids in question with amines. It is shown that the data on the boric acid reaction with amines are contradictory and, at present, there is no confirmed information on obtaining a covalent bond between boron and nitrogen without the involvement of hydroxyl groups and the cyclic systems formation, for example, in the oxazaborolidines case. Literary searches have shown that the report on the anilinboronic acid production in 1963 was not developed, and there is also no data on the synthesis of those compounds. Along with this, boric acid easily forms borate salts of various configurations with amines, that is confirmed by modern methods of analysis (IR- and NMR-spectroscopy, elemental analysis). It has also been shown that boric acid is capable of forming compounds with an intramolecular donor-acceptor bond between boron and nitrogen. The theoretical calculations results and experimental data on the arylboronic acids interaction, with various aromatic ring substituents, with pyrocatechines, o-phenylenediamines, 2-hydroxybenzenetiols and o-benzenedithiols are presented. It is noted that competitive formation of anhydride-like structures is observed in all these reactions. It is shown that the interaction with pyrocatechins is the most thermodynamically advantageous. In the arylboronic acids reaction with ortho-benzenedithiols, ortho-hydroxybenzenetiols in chloroform, the corresponding oxathiaboroles and dithiaboroles were not isolated. The latter were obtained by the boron trichloride reaction with the corresponding electron donors. It is reported that there is no information on the preparation of condensation products of phenylboronic acids with aniline and benzylamine. For citation: Strokova S.V., Lenskiy M.A. Boron-nitrogen compounds in the reaction of boric and boronic acids with amines. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 6. P. 6-13. DOI: 10.6060/ivkkt.20246706.6988.

RECOVERY OF BORON WASTES WITH INORGANIC ACID

Approximately 73-74% of boron mineral reserves all over the world are located in the Western Anatolian region of Turkey, in the provinces of Eskişehir, Kütahya, Balıkesir, and Bursa. The most intense minerals extracted from these fields are colemanite, ulexite, and tincal minerals, respectively. The general principle in the recovery of these minerals is to extract the raw ore and obtain it by size reduction processes of concentrates in high grade. In addition to concentrates, boric acid (H3BO3) production is also possible in Balıkesir and Kütahya. The production of this acid in question includes a series of processes from dissolution with sulfuric acid at high temperatures to crystallization. In this study, except for the aforementioned high concentrations, boron recovery from clay waste, which is high in boron content and is collected from plant waste ponds, is investigated. For this purpose, ulexite-colemanite-containing slime wastes of the Bigadiç (Balıkesir) Plant were dissolved in 7% solids at 60°C in different sulfuric acid concentrations (1-6% H2SO4) and were obtained with 83-97% B2O3 recovery. When the boron wastes are evaluated, issues such as the discovery and establishment of a new waste pond/dam will be solved, the valuable content in the wastes will be recovered, and the environmental problems of boron and other contents in clay will be eliminated. This article includes information about the characterization of the structure by considering the dissolution of boron and other compounds, as well as obtaining boric acid from inorganic acid and boron wastes.

The Importance of 6-Aminohexanoic Acid as a Hydrophobic, Flexible Structural Element.

6-aminohexanoic acid is an ω-amino acid with a hydrophobic, flexible structure. Although the ω-amino acid in question is mainly used clinically as an antifibrinolytic drug, other applications are also interesting and important. This synthetic lysine derivative, without an α-amino group, plays a significant role in chemical synthesis of modified peptides and in the polyamide synthetic fibers (nylon) industry. It is also often used as a linker in various biologically active structures. This review concentrates on the role of 6-aminohexanoic acid in the structure of various molecules.

Insecticidal Effects of Plasma Treated Water.

The efficacy of plasma-treated tap water (PTW) for the possible treatment of a mealybug (Planococcus citri) infestation was studied under laboratory conditions. Mealybugs growing on Nerium oleander have been treated using PTW after being transferred to Petri dishes, thus avoiding possible buffering effects that might occur in an in-situ study. When treating tap water with a dielectric barrier discharge for several minutes (1, 3, 5 and 10 min) a distinct acidification of the water can be determined, resulting in a pH value of 1.8 after 10 min treatment. The efficacies of the treated tap water samples were compared to the efficacies achieved using classically acidified water. The classical acidification of tap water was carried out using nitric acid and hydrochloric acid to see any possible influences of the salt of the acid in question. The application of PTW revealed high mortality rates of approx. 90% after an observation period of 24 h. PTW appears promising for the treatment of smaller plant stock and commodities as produced by small scale farmers or in greenhouses as an environmentally friendly substitute or supplement to conventional pesticides.

Complementary Cell-Free Translational Assay for Quantification of Amino Acids.

In this study, we present a simple and economical method that enables rapid quantification of amino acids based on their polymerization into a signal-generating protein. This method harnesses amino acid-deficient cell-free protein synthesis systems that generate fluorescence signals in response to exogenous amino acids. When premixed with assay samples containing the amino acids in question, incubation of the cell-free synthesis reaction mixture rapidly resulted in the production of sfGFP, the fluorescence intensity of which was linearly proportional to the concentration of the amino acids. The assay method achieved a limit of detection as low as ∼100 nM and was successfully applied to the quantification of disease-related amino acids in biological samples. Compared with standard methods in current use that require chemical derivatization of amino acids and chromatographic equipment, the complementation assay method developed in this work enables the direct translation of amino acid titer into measurable biofluorescence intensity in a much shorter period, providing a more affordable and flexible option for the quantification of amino acids.

Directed improvement of luciferin regenerating enzyme binding properties: implication of some conserved residues in luciferin-binding domain.

Luciferin regenerating enzyme (LRE) contributes to in vitro recycling of d-luciferin to produce persistent and longer light emission by luciferase. Luciferin binding domains I and II among LREs regarded as potential candidates for luciferin-binding sites. In this study, for the first time, amino acids T69, G75 and K77 located at luciferin binding domain I of LRE from L. turkestanicus (T-LRE) substituted by using site-directed mutagenesis. Single mutant T(69)R increased luciferase light output more than two-fold over a longer time in comparison with a wild-type and other mutants of T-LRE. Nevertheless, double mutant (K(77)E/T(69)R) increased the amount of bioluminescent signal more than two-fold over a short time. In addition, G(75)E, K(77)E and G(75)E/T(69) R mutants did not improve luciferin-luciferase in vitro bioluminescence. Based on our results, addition of K(77)E/G(75)E and K(77)E/G(75)E/T(69)R mutants caused intermediate changes in bioluminescence from in vitro luciferin-luciferase reaction. These findings indicated that the amino acids in question are possible to be located within T-LRE active site. It may also be suggested that substituted Arg69 (Arg218) plays an important role in luciferin binding and the existence of Gly75 as well as Lys77 is essential for T-LRE which has already evolved to have different functions in nature.

Efeito dos ácidos lático e butírico, isolados e associados, sobre o desempenho e morfometria intestinal em frangos de corte

During the last years, the national poultry keeping has suffered constant challenges, having as objective to diversify the consuming market of the broiler to around of the world. However, each market presents different requirements, as in the case of the European market that establishes the exclusion of antibiotics as promotional of growth in the feeding of the broilers. Aiming at this problematic one, this study was become fullfilled, with the objective to analyze the results of the association of the butyric and lactic acids as additives in the ration of broilers, in comparison to the results gotten for the usually used promoters of growth in the diets of broilers. They had been evaluated: the animal performance, humoral immunology and intestinal morfometric of the birds. 1400 male chickens of the commercial ancestry Ross had been used, dividing them in five groups with different treatments to that if it relates to the additive use. Being a group it has controlled absent of additive, a group with butyric acid, a group with lactic acid, the fourth group with the association of butyric and lactic acids, and the fifth group with avilamicina (antibiotic) as promotional of traditionally used growth in the production of broilers. The performance results had indicated that the interaction of acid ones was significant in the initial phase, mean while did not occur an additive effect of acid ones, being the use of the butyric acid separately more recommendable during this phase. Already in the growth phase, the interaction was significant with an additive effect, recommending its use in the rations of growth. In accordance with the average headings of antibodies gotten in the study, the interaction was significant in the third sampling and showed a synergic effect of acid ones, being the combination of acids in question a powerful modulator of the humoral immunity. Meanwhile, the results gotten in the analyses of intestinal morfometric had not been conclusive. In general terms, one requires more organic acid studies that confirm the use of as the promotional ones of growth.

A tingle of extra excitement with voltage dependence of NMDA receptor activation

A tingle of extra excitement with voltage dependence of NMDA receptor activation

Reliability of results and interpretation of measures of 3-methylhistidine in muscle interstitium as marker of muscle proteolysis

TO THE EDITOR: We were interested in the contribution by Tesch and colleagues to the evidence base concerning the events subsequent to acute immobilization in human muscle. Tesch and colleagues (14) used a microdialysis technique applied to human muscle in an attempt to measure an index of myofibrillar proteolysis 72 h after immobilization using the unilateral leg suspension technique. The authors discuss their results as though they had good evidence that the technique they used produces results that are sufficiently firm to be the basis of conjecture about mechanisms of protein balance in muscle after immobilization. We demur and propose that they are on very shaky ground. First, we wonder about the size of the effect reported. The authors claim it to be 44%, but calculation of the change shows it to be actually 29% with the SEs sufficiently large that they almost span the difference; SDs must overlap. Significance at the 5% level can only barely have been reached. Are the authors convinced that they have not ignored a type I error? The authors (14) begin their explanation of the advantages of the dialysis technique using 3-methylhistidine (3MeHis) by describing the gold standard method, i.e., the stable isotopelabeled amino acid tracer dilution method, as cumbersome and possibly unjustified in study of otherwise healthy subjects. We find this notion strange since Ferrando and colleagues (6, 12) have used the technique in many studies of how immobilization affects muscle protein turnover subsequent to disuse. We have also used the techniques in a wide variety of studies of proteolysis in healthy and infirm subjects (1, 2, 10, 11, 15) with no problems and, we would propose, producing results with a greater degree of certainty and biological appropriateness than those obtained by the 3MeHis dialysis technique.

The intrinsic conformational propensities of the 20 naturally occurring amino acids and reflection of these propensities in proteins

Here, we compare the distributions of main chain (Phi,Psi) angles (i.e., Ramachandran maps) of the 20 naturally occurring amino acids in three contexts: (i) molecular dynamics (MD) simulations of Gly-Gly-X-Gly-Gly pentapeptides in water at 298 K with exhaustive sampling, where X = the amino acid in question; (ii) 188 independent protein simulations in water at 298 K from our Dynameomics Project; and (iii) static crystal and NMR structures from the Protein Data Bank. The GGXGG peptide series is often used as a model of the unstructured denatured state of proteins. The sampling in the peptide MD simulations is neither random nor uniform. Instead, individual amino acids show preferences for particular conformations, but the peptide is dynamic, and interconversion between conformers is facile. For a given amino acid, the (Phi,Psi) distributions in the protein simulations and the Protein Data Bank are very similar and often distinct from those in the peptide simulations. Comparison between the peptide and protein simulations shows that packing constraints, solvation, and the tendency for particular amino acids to be used for specific structural motifs can overwhelm the "intrinsic propensities" of amino acids for particular (Phi,Psi) conformations. We also compare our helical propensities with experimental consensus values using the host-guest method, which appear to be determined largely by context and not necessarily the intrinsic conformational propensities of the guest residues. These simulations represent an improved coil library free from contextual effects to better model intrinsic conformational propensities and provide a detailed view of conformations making up the "random coil" state.

Engineering Neutral Organic Bases and Superbases by Computational DFT Methods – Carbonyl Polyenes

AbstractThe gas‐phase proton affinities and basicities of a large number of open‐chain zig‐zag polyenes involving a carbonyl functional group were examined by using the B3LYP/6‐311+G(d,p)//B3LYP/6‐31+G(d) computational scheme. Absolute proton affinities (APAs) increased with the number of polyene subunits. The most basic site in all cases was the carbonyl oxygen. It was conclusively shown that basicity of polyenes was dramatically amplified by substitution of NMe2 and Me groups at the strategic positions on the molecular backbone. Triadic analysis revealed that the dominating effect was relaxation energy released upon formation of the molecular radical cations. Relation between the relaxation and cationic resonance effect was briefly discussed. Moreover, it was shown that the carbonyl oxygen was more basic than the amino nitrogen of the NMe2 groups because of the larger bond association energy of the hydrogen atom attached to O compared to N atoms, in the conjugate acid in question. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Perl algorithm to calculate and categorize Phi and Psi angles in a protein

In order for a Biochemist to come to sufficient understanding of the structure of a protein, it is important that she know the phi and psi angles for each amino acid within that protein. Phi and psi angles are the measurements, in degrees, of the arrangement of the two amino acids on either side of a given amino acid in a peptide chain. The phi and psi angles are calculated based on information gathered from X-ray crystallography, which allows for the location of each atom in a protein to be defined in terms of its position on a three dimensional plane. The x, y, z coordinates of four different atoms must be obtained in order to perform the phi and psi calculations. To calculate phi, the coordinates of the Nitrogen, Alpha Carbon, and Carbon of the amino acid in question, as well as the location of the Carbon in the preceding amino acid, must be available. To calculate psi, the coordinates of the Nitrogen, Alpha Carbon and Carbon, as well as Nitrogen of the following amino acid in the chain, are needed. When all appropriate coordinates are collected, the next step in the calculation is to identify the dihedral angle.

Happily at Work

Happily at Work

Humic acids: Their detergent qualities and potential uses in pollution remediation

Humic acids are amphiphilic species whose behavior in aqueous solution suggests that they form pseudomicelles–aggregates akin to the micelles familiar from synthetic surfactant chemistry. It is thought that humic pseudomicelles can be formed by both intramolecular coiling and intermolecular association, depending on the molecular weight, structural characteristics, and polydispersity of the humic acid in question. The process does not feature a critical micelle concentration. Experimental evidence indicates that metal ions enhance the detergent character of dissolved humic acid by facilitating the coiling and folding of the polymer chains. A recently conceived alternative model suggests that humic acids consist of relatively small subunits that associate through weak molecular interactions. This view appears to run counter to certain experimental observations, but deserves careful attention. The strong association between metal ions and solid humic acid makes it possible to use an inexpensive commercial grade for the decontamination of polluted water. A continuous elution process through a column packed with humic acid allows for the removal of both heavy metals and organic xenobiotics from aqueous solution.

Immobilization of aqueous pyrene by dissolved humic acid

Pyrene is frequently used as a fluorescent probe in the study of solution environments. Purging with nitrogen is a common practice for the elimination of oxygen from solutions, but this procedure leads to the loss of pyrene through carry-over in the nitrogen stream. The presence of humic acid in solution, even in small quantities, can have a significant retarding effect on this evaporation of pyrene. Based on the detergent model of humic acid, this is ascribed to its ability to sequester pyrene in pseudomicellar structures. This immobilization of pyrene has been found to depend on the molecular size and flexibility of the humic acid in question. The presence of metal ions in solution also exerts a strong influence by enhancing the detergent character of the humic acid. The degree of pyrene immobilization by dissolved humic acid can be used as a measure of its association with hydrophobic species.

Diethyl pyrocarbonate as a probe of protein-DNA interactions.

A rigorous study of the interactions between DNA and proteins or other molecules requires the accumulation of a wide range of information regarding the nature of such an interaction, Among the parameters on which it is desirable to gain information are: the size and number of the binding site(s) on the nucleic acid in question, the sequence specificities of the binding events, the strength of the interaction, the biochemical effects of the binding, and the structural consequences of such an interaction on all the molecules concerned.

Occurrence of an unusual amount of an odd-numbered fatty acid in glycosphingolipids from human cataracts.

Human cataractous glycosphingolipids were isolated and purified according to previously established procedures. Fatty acid analyses of the purified glycosphingolipid revealed the presence of a significant amount of an odd-chain fatty acid. This was confirmed by methane (CH4) chemical ionization mass spectrometry, which showed characteristic ions at m/z 397, 425, 437, and 365. These ions facilitated the determination of molecular weight and the assignment of C25:0 (n-pentacosanoic acid) to this fatty acid in question. This may be the first time that such an unusual distribution of a single odd-chain fatty acid has been shown to occur in glycosphingolipid from any tissue.

Urinary amino acid excretion and plasma amino acid concentration in dogs fed crystalline amino acid diets

Plasma amino acid concentrations and urinary amino acid excretion were exanined in Pointer puppies fed a crystalline amino acid diet. Amino acids accounted for only a small percentage (1.7%) of total urinary nitrogen (N). In addition, amino acid excretion accounted for a low percentage (<1%) of amino acid intake. A complete urinary amino acid profile is presented. Free amino acid concentrations in plasma were examined at 0, 45, 90, 150, 210 and 300 minutes after feeding. Both the amount of time required for an ingested amino acid to reach its highest plasma concentration and the length of time plasma amino acid concentration remained elevated depended upon the amino acid in question. These data provide useful information for determining the optimal postprandial time for bleeding dogs fed a purified diet.

Plasma amino acid levels in the first few days after burn injury and their predictive value.

Plasma amino acid concentrations were studied in 27 burn subjects on the day of injury and on day 4, as a function of the burn surface area and the outcome. On the day of injury, compared to normal subjects, plasma amino acid levels were generally higher in the most severely burned patients (significantly for ALA, GLY, HYP and PHE) and in nonsurvivors (significantly for ALA, PHE, GLY, PRO and ORN). In burn patients all initial values were higher in nonsurvivors than in survivors; for ALA, GLY, and LEU, the difference was significant. Between the day of injury and day 4, different variations were noticed depending on the amino acid in question and the outcome. On day 4, plasma amino acid levels were lower in nonsurvivors, significantly for GLU + GLN, THR, SER, PRO, ASP + ASN, LEU, ILEU and VAL. Our data suggest that plasma amino acid determination could be used as an accurate element of prognosis after burn injury.

The utilization of exogenous taurine for the conjugation of xenobiotic acids in the ferret.

Although the occurrence of the taurine conjugation mechanism for various xenobiotic acids is well established, nothing is known of the source of the taurine used for this conjugation. [14C]Taurine was administered alone and in combination with 2-naphthylacetic acid or clofibric acid (both of which are known to form taurine conjugates) to to ferrets, and the 0--24 h urine collected. Of the dose of [14C]taurine, 26% was recovered in the urine in 24 h and the only 14C-containing material present was unchanged taurine. When either 2-naphthylacetic acid or clofibric acid was co-administered with [14C]taurine, 21 and 17%, respectively, of the 14C dose was recovered in the 0--24 h urine. In both cases, two 14C compounds were present--unchanged taurine (minor) and the taurine conjugate of the acid in question (major). Comparison of these results with those previously obtained with 14C-labelled 2-naphthylacetic and clofibric acids, shows that the taurine used for their conjugation is derived from a pool freely accessible to exogenous taurine. The results are discussed in terms of the availability for metabolic utilization of taurine in the animal body, and of the use of co-administration of [14C]taurine with a xenobiotic acid for the identification of taurine conjugates.