Zur Untersuchung von Gleichgewichten instabiler Komplexe und die Bestimmung der Beweglichkeiten der einzelnen Spezies mittels Gegenstrom-Ionenwanderung / Investigation of the Equilibrium of Unstable Complexes and the Determination of their Mobility by Means of Countercurrent Ion Migration

1973 ◽  
Vol 28 (7) ◽  
pp. 1226-1227 ◽  
Author(s):  
B. A. Bilal
Keyword(s):  
Metal Cation ◽  
Total Concentration ◽  
Migration Process ◽  
Stationary Distributions ◽  
Ion Migration ◽  
Constant Distribution

In a countercurrent ion migration process the ion of an element (e. g. a metal cation) can form various unstable complexes with the anion of the countercurrent electrolyte. The total concentration of such an element in its stationary and locally constant distribution in a countercurrent ion migration column is then determined by the average mobility of all equilibrated species containing this element. From stationary distributions in their dependence on concentration the mobilities of the various species can be determined if the constants of the different equilibrium stages are known and vice versa.

Wechselwirkungen in Molekülkristallen, 160 [1,2]. Kristallzüchtung und Strukturbestimmung der verschiedenartigen Polyphenyl-Kontaktionenmultipel [p-Quaterphenylee⊖⊖][Na⊕(DME)3]2, [p-Quaterphenyl⊖⊖(Na⊕(THF)3)2] und [p-Terphenyl⊖⊖Na⊕(DME)2Na⊕(DME)]2 / Interaction in Molecular Crystals, 160 [1, 2]. Crystallization and Structure Determination of the Different Polyphenyl Contact Ion Multiples [p-Quaterphenylee⊖⊖][Na⊕(DME)3]2, [p-Quaterphenyl⊖⊖(Na⊕(THF)3)2] und [p-Terphenyl⊖⊖Na⊕(DME)2Na⊕(DME)]2

2000 ◽  
Vol 55 (12) ◽  
pp. 1103-1113 ◽  
Author(s):  
Hans Bock ◽  
K. Gharagozloo-Hubmann ◽  
M. Sievert
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Sodium Salt ◽  
Structure Determination ◽  
Metal Cation ◽  
Molecular Crystals ◽  
Sodium Salts ◽  
Structure Determinations ◽  
Cation Coordination

The π-hydrocarbons p-terphenyl and p-quaterphenyl are reduced to their dianions in aprotic solutions of different ethers at sodium metal mirrors. Single crystal structure determinations of the solvent-separated or solvens-shared contact ion multiples, [p-terphenyl⊖⊖ Na⊕(DME)2Na⊕DME]2, p-quaterphenyl⊖⊖ ][Na⊕(DME)3]2 and [p-quaterpheny⊖⊖( Na⊕(THF)3)2], prove the essential cation solvation by the chelating dimethoxyethane (DME) versus the bulky tetrahydrofuran (THF) ligands: The solution network of equilibria between solvent separated and solvent shared ion aggregates can be considerably and transparently modified by the ether solvent selected. In addition, the structures of the monomeric sodium salts reveal partly novel details of metal cation coordination by contacts Na⊕ ··· O as well as Na⊕ ··· Cπ such as in the dimeric sodium salt of p-terphenyl dianion, [(DME)2Na⊕ (terphenyl⊖⊖)(Na⊕ DME)(terphenyl⊖⊖)Na⊕ (DME)2].

scholarly journals Mechanism of tubulin–colchicine recognition: a kinetic study of the binding of the colchicine analogues colchicide and isocolchicine

1997 ◽  
Vol 327 (3) ◽  
pp. 685-688 ◽  
Author(s):  
Chantal DUMORTIER ◽  
Qunying YAN ◽  
Susan BANE ◽  
Yves ENGELBORGHS
Keyword(s):  
Rate Constant ◽  
Total Concentration ◽  
Carbonyl Oxygen ◽  
Protein Fluorescence ◽  
Kinetic And Thermodynamic Parameters ◽  
Methoxy Groups ◽  
Displacement Experiments ◽  
Absorbance Changes ◽  
Initial Binding

Colchicide (IDE) is a colchicine (COL) analogue in which the C-10 methoxy group is replaced by a hydrogen atom. Its binding to tubulin is accompanied by a quenching of the protein fluorescence. The fluorescence decrease shows a monoexponential time dependence. The observed rate constant increases in a non-linear way with the total concentration of IDE, allowing the determination of a binding constant for an initial binding site (K1 = 5300±300 M-1) and the rate constant for the subsequent isomerization (k2 = 0.071±0.002 s-1) at 25 °C. The rate constant, k-2, for the reversed isomerization can be determined by displacement experiments. Despite the minor alteration of the C-ring substituent, the kinetic and thermodynamic parameters of binding are substantially different from those of COL itself, for both steps. In isocolchicine (ISO) the carbonyl oxygen atom and the methoxy groups of the C-ring have been interchanged. Its binding to tubulin only results in small fluorescence and absorbance changes. Therefore competition experiments with MTC [2-methoxy-5-(2ʹ,3ʹ,4ʹ-trimethoxyphenyl)-2,4,6-cycloheptatrien-1-one] were performed. ISO competes rapidly and with low affinity with MTC. Fluorimetric titrations of tubulin with MDL (MDL 27048 or trans-1-(2,5 dimethoxyphenyl)-3-[4-(dimethylamino)phenyl]-2-methyl-2-propen-1-one) in the presence and absence of ISO give evidence for the existence of a second, slow-reacting low-affinity site for ISO that is not accessible to MTC or MDL. The relevance of these results for the recognition of COL is analysed.

scholarly journals Determination of Surfactants in Environmental Samples. Part II. Anionic Compounds

2013 ◽  
Vol 20 (2) ◽  
pp. 331-342 ◽  
Author(s):  
Ewa Olkowska ◽  
Marek Ruman ◽  
Anna Kowalska ◽  
Żaneta Polkowska
Keyword(s):  
Environmental Samples ◽  
Anionic Surfactants ◽  
Solid Phase ◽  
Total Concentration ◽  
Polar Group ◽  
Surface Active Agents ◽  
Assisted Extraction ◽  
Surface Active ◽  
Living Organisms

Abstract Surface active agents (SAA) with negative charge of polar group are named as anionic compounds. They are the main constituent of most products containing synthetic surfactants. The linear alkylbenzene sulfonates (LAS), alkyl ethoxysulfates (AES) and alkyl sulfates (AS) are typically applied from this class of compounds. Those surfactants are ingredients of household detergents and cleaners, laundry detergents, cosmetic etc. Moreover they can be applied in the paper, textile and tanning industry as optical brighteners, dispersant, wetting and suspending agents. They can be substrates in the formulation of different products like dyes, pigments, pesticides, exchange resins, plasticizers and pharmaceuticals. Anionic surfactants after use are passed into sewage-treatment plants, where they are partially degraded and adsorbed to sewage sludge (applied in agriculture fields). Finally, the anionic SAA or their degradation products are discharged into surface waters and onto bottom sediments, soils or living organisms. Therefore, it is important (widely application, bioaccumulation, toxicity for living organisms) to investigate the environmental fate of those class of compounds in more details. This research involves determination the concentration of anionic surfactants with use appropriated analytical techniques in environmental samples The official methodology for determination of anionic SAA in liquid samples is based on the ion-pair reaction of these analytes compounds with methylene blue (MB) and an extraction with toxic solvent chloroform. During isolation step of anionic compounds from solid samples are employed Soxhlet and ultrasonic-assisted extraction techniques with use of methanol or mixture of other organic solvents as extraction medium. To overcome disadvantages of those traditional techniques were applied following techniques at sample preparation step from liquid and solid matrices: solid-phase extraction (SPE) and solid-phases microextraction (SPME); accelerated solvent extraction (ASE), microwave-assisted extraction (MAE), supercritical fluid extraction (SFE), respectively. For estimate total concentration of anionic analytes in extracts the spectrophotometric technique is used (as official regulation). For determination concentration of individual analytes were applied gas (derivatization step requires) and liquid chromatography mainly with mass spectrometry technique. The presence of anionic surface active agents was confirmed in various ecosystems (liquid and solid environmental samples).

Determination of the Total Concentration of Halogen- and Sulfur-Organic Compounds in Vegetable Oils of Different Degrees of Purity—a New Approach to Assessing Their Safety

2020 ◽  
Vol 75 (8) ◽  
pp. 1054-1058
Author(s):  
I. A. Revel’skii ◽  
M. E. Chivarzin ◽  
D. S. Khaibullin ◽  
M. A. Gerasimov ◽  
A. M. Dolgonosov ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Vegetable Oils ◽  
Total Concentration ◽  
New Approach

scholarly journals Distribution and Fractionation of Heavy Metals in Sediments of Karra River, Hetauda, Nepal

2015 ◽  
Vol 19 (2) ◽  
pp. 123-128 ◽  
Author(s):  
Sadhana Pradhanang
Keyword(s):  
River Sediment ◽  
Total Concentration ◽  
Extraction Procedure ◽  
Residual Fraction ◽  
High Concentration ◽  
Metal Concentrations ◽  
Mn Oxide ◽  
Fractionation Analysis ◽  
Polluted Sites

A five-step sequential extraction procedure was applied for the determination of the distribution of four elements (Cr, Mn, Fe, and Ni) in sediment of the Karra River. Sediment samples were collected from 16 different sites in the Karra River (upstream, industrial belt, downstream). The distribution of trace metals among exchangeable, carbonate, reducible, oxidizable and residual fractions were determined. The total concentration of metals varies in the range of Cr 72–4339.54 mg kg?1, Mn 22–411.93 mg kg?1, Fe 2967.23-32423.0 mg kg?1 and Ni 31.70-180.74 mg kg?1. The accuracy evaluated by comparing total trace metal concentrations with the sum of the five individual fractions proved to be satisfactory. The chemical speciation of Cr, Mn, Fe, and Ni in most sampling stations were in the order of residual > reducible > oxidazable > carbonate> exchangeable. Fractionation analysis showed that dominant metals are in residual fraction. The highest metal concentrations were observed at the most polluted sites of the industrial belt. High concentration of chromium was found in the Fe-Mn oxide and organic fraction in some of the sites of industrial belt.Journal of Institute of Science and Technology, 2014, 19(2): 123-128

scholarly journals Quantitative determination of Ca2+-dependent Mg2+-ATPase from sarcoplasmic reticulum in muscle biopsies

1989 ◽  
Vol 260 (2) ◽  
pp. 443-448 ◽  
Author(s):  
M E Everts ◽  
J P Andersen ◽  
T Clausen ◽  
O Hansen
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Soleus Muscle ◽  
Human Subjects ◽  
Vastus Lateralis ◽  
Total Concentration ◽  
Vastus Lateralis Muscle ◽  
Lateralis Muscle ◽  
32P Incorporation ◽  
Muscle Biopsies

The possibility of quantifying the total concentration of Ca2+-dependent Mg2+-ATPase of sarcoplasmic reticulum was investigated by measurement of the Ca2+-dependent steady-state phosphorylation from [gamma-32P]ATP and the Ca2+-dependent 3-O-methylfluorescein phosphatase (3-O-MFPase) activity in crude muscle homogenates. The Ca2+-dependent phosphorylation at 0 degree C (mean +/- S.E.) was 40.0 +/- 2.5 (n = 6) and 6.2 +/- 0.7 (n = 4) nmol/g wet wt. in rat extensor digitorum longus (EDL) and soleus muscle, respectively (P less than 0.001). The Ca2+-dependent 3-O-MFPase activity at 37 degrees C was 1424 +/- 238 (n = 6) and 335 +/- 56 (n = 4) nmol/min per g wet wt. in rat EDL and soleus muscle, respectively (P less than 0.01). The molecular activity calculated from these measurements amounted to 35 +/- 5 min-1 (n = 6) and 55 +/- 10 min-1 (n = 4) for EDL and soleus muscle respectively. These values were not different from the molecular activity calculated for purified Ca2+-ATPase (36 min-1). The Ca2+-dependent 32P incorporation in soleus muscle decreased in the order mice greater than rats greater than guinea pigs. In EDL muscles from hypothyroid rats at a 30% reduction of the Ca2+-dependent phosphorylation was observed. The Ca2+-dependent phosphorylation in vastus lateralis muscle from three human subjects amounted to 4.5 +/- 0.8 nmol/g wet wt. It is concluded that measurement of the Ca2+-dependent phosphorylation allows rapid and reproducible quantification of the concentration of Ca2+-dependent Mg2+-ATPase of sarcoplasmic reticulum. Since only 20-60 mg of tissue is required for the measurements, the method can also be used for biopsies obtained in clinical studies.

Sign in / Sign up

Export Citation Format

Share Document