Modulating the pKa Values of Hill-Type pH Probes for Biorelevant Acidic pH Range

2020 ◽  
Author(s):  
Yansheng Xiao ◽  
Fang Hu ◽  
Xiao Luo ◽  
Mingming Zhao ◽  
Zhenglong Sun ◽  
...  
Keyword(s):  
Acidic Ph ◽  
Pka Values ◽  
Ph Range ◽  
Ph Probes

Synthesis and 31 P NMR characterization of new low toxic highly sensitive pH probes designed for in vivo acidic pH studies

2002 ◽  
Vol 10 (5) ◽  
pp. 1451-1458 ◽  
Author(s):  
Sophie Martel ◽  
Jean-Louis Clément ◽  
Agnès Muller ◽  
Marcel Culcasi ◽  
Sylvia Pietri
Keyword(s):  
Acidic Ph ◽  
Highly Sensitive ◽  
Nmr Characterization ◽  
Low Toxic ◽  
Ph Probes

scholarly journals Evidence that the active centre of chymopapain A is different from the active centres of some other cysteine proteinases and that the Brønsted coefficient (βnuc.) for the reactions of thiolate anions with 2,2′-dipyridyl disulphide may be decreased by reagent protonation

1980 ◽  
Vol 189 (1) ◽  
pp. 189-192 ◽  
Author(s):  
K Brocklehurst ◽  
B S Baines ◽  
M S Mushiri
Keyword(s):  
Carica Papaya ◽  
Cysteine Proteinases ◽  
Active Centre ◽  
Pka Values ◽  
Nitrobenzoic Acid ◽  
Specific Reactivity ◽  
Ph Range ◽  
Thiolate Anions ◽  
Active Centres

The active centres of chymopapains A and B (jointly designated EC 3.4.22.6) and papaya (Carica papaya L.) peptidase A were investigated by using 2,2′-dipyridyl disulphide and 5,5′-dithiobis-(2-nitrobenzoic acid) as thiol-specific reactivity probes. Whereas the first active-centre pKa values for chymopapain B and papaya peptidase A are less than 5, is as the case for papain (EC 3.4.22.2) and ficin (EC 3.4.22.3), that for chymopapain A is about 6.8. The reason why the reactions of thiols of pKa approx. 6.5 with 2.2′-dipyridyl disulphide are essentially pH-independent in the pH range around the thiol pKa is delineated. The value of the Brønsted coefficient (beta nuc.) for the reactions of thiolate ions with the 2,2′-dipyridyl disulphide monocation appears to be smaller than its value for the corresponding reactions with the neutral disulphide.

Peptic digestibility of raw and heat-coagulated hen's egg white proteins at acidic pH range

2004 ◽  
Vol 55 (8) ◽  
pp. 635-640 ◽  
Author(s):  
Kenji Yoshino ◽  
Kentaro Sakai ◽  
Yoko Mizuha ◽  
Ayako Shimizuike ◽  
Shigeru Yamamoto
Keyword(s):  
Egg White ◽  
Acidic Ph ◽  
Egg White Proteins ◽  
Hen’S Egg ◽  
Ph Range

scholarly journals Effective Removal of Fluoride onto Metal Ions Loaded Orange Waste

2012 ◽  
Vol 27 ◽  
pp. 61-66 ◽  
Author(s):  
Kedar Nath Ghimire
Keyword(s):  
Metal Ions ◽  
Removal Efficiency ◽  
Orange Juice ◽  
Experimental Results ◽  
Fluoride Removal ◽  
Acidic Ph ◽  
Neutral Ph ◽  
Effective Removal ◽  
Orange Waste ◽  
Ph Range

Removal of fluoride is investigated onto several metal ions loaded phosphorylated orange juice residue and commercially available alumina. The experimental results revealed that cerium (IV) loaded phosphorylated orange waste indicated excellent fluoride removal efficiency at acidic pH range and while that lanthanum loaded at neutral pH range. Both the metal loaded adsorbents are found superior to the commercially available activated alumina.DOI: http://dx.doi.org/10.3126/jncs.v27i1.6660 J. Nepal Chem. Soc., Vol. 27, 2011 61-66 

Metal-contaminant leaching from lead smelter fly ash using pH-stat experiments

2008 ◽  
Vol 72 (1) ◽  
pp. 521-524 ◽  
Author(s):  
M. Vítková ◽  
V. Ettler ◽  
O. Šebek ◽  
M. Mihaljevič
Keyword(s):  
Fly Ash ◽  
Acidic Ph ◽  
Lead Smelter ◽  
Leaching Experiments ◽  
Ph Stat ◽  
Ph Range ◽  
Metal Contaminant ◽  
Leaching Procedure

AbstractFly ash from secondary Pb metallurgy was submitted to the pH-static leaching procedure according to the PrEN 14997 European leaching standard. The 48 h pH-static leaching experiments were performed on (1) fresh untreated fly ash and (2) previously washed fly ash with a cumulative wash step of 60 l kg-1. Greater release ofmetallic contaminants (Pb, Cd, Zn) was observed in the acidic pH range for both ashes. Washing significantly reduced the release of Cd and Zn, but greater concentrations of Pb were observed in leachates from washed fly ash due to the more important leaching of anglesite (PbSO4). The PHREEQC-2 speciation-solubility calculations showed that anglesite, phosgenite (PbCl2·PbCO3) and laurionite (Pb(OH)Cl) are the most important solubility-controlling phases for Pb, which is the most important contaminant.

scholarly journals INTERACTION OF CIS-Pd(NH3)2Cl2 WITH DIPHOSPHONIC ACIDS IN SOLUTIONS AT PHYSIOLOGICAL CHLORIDE-IONS CONCENTRATION

2019 ◽  
Vol 85 (11) ◽  
pp. 3-14
Author(s):  
Oleksandra Kozachkova ◽  
Nataliia Tsaryk ◽  
Vasyl Pekhnyo
Keyword(s):  
Complex Formation ◽  
Equilibrium Concentration ◽  
Chloride Ions ◽  
Ion Concentration ◽  
Acidic Ph ◽  
Bidentate Coordination ◽  
Aqua Complexes ◽  
Diphosphonic Acids ◽  
Ph Range ◽  
Oxygen Atoms

The complex formation of cis-Pd(NH3)2Cl2 with 1-hydroxyethylidene-1,1-diphosphonic (HEDP, H4L1), 3-amino-1-hydroxypropylidene-1,1-diphosphonic (AHPrDP, H4L2), and 1-aminopropylidene-1,1-diphosphonic (APrDP, H4L3) acids in aqueous solutions with the concentration CKCl=0.15 mol/L, which corresponds to the concentration of chloride ions in the intercellular fluid, has been studied by spectrophotometry and pH potentiometry. The results of studying the interaction between cis-Pd(NH3)2Cl2 and diphosphonic acids have been interpreted taking into account the equilibrium concentration distribution of complexes forming in Pd(NH3)2Cl2 solutions at a chloride ion concentration of 0.15 mol/L. It has been found that when Pd(NH3)2Cl2 is dissolved in 0.15 mol/L KCl, ammonia molecules are substituted by chloride ions and a water molecule in the pH range of 2 – 4 to form chloro-aqua complexes [PdCl4]2- and [PdCl3(H2O)]-. In the case of complex formation of Pd(II) chloro-aqua complexes with HEDP and AHPrDP, complexes with [Pd 2OPO3 2Cl] chromophore with bidentate coordination of ligands by two oxygen atoms of phosphonic groups are formed in the acidic pH range. At pH>5, a [Pd(L1)(NH3)2]2- complex (lgβ=30.55(5)) is formed in the cis-Pd(NH3)2Cl2:HEDP=1:1 system, and at pH>6, a [Pd(HL2)(NH3)2]- complex (lgβ=40.29(2)) is formed in the cis-Pd(NH3)2Cl2:AHPrDP=1:1 system. The formation of complexes with [Pd 2OPO3 2Namine] chromophore takes place with the displacement of chloride ions from the coordination sphere of complexes with [Pd 2OPO3 2Cl] chromophore by ammonia molecules. In the system cis-Pd(NH3)2Cl2:APrDP=1:1, the ligand is coordinated to Pd(II) in a bidentate fashion by the nitrogen atoms of the amine group and oxygen atoms of the phosphonic group to form a [Pd(H2L3)Cl2]2- complex with [Pd Namine OPO3 2Cl] chromophore in the acidic pH range. When pH is increased to 5 and then to 7, a sequential substitution of chloride ions by ammonia molecules takes place to form a [Pd(HL3)(NH3)Cl]2- complex (lgβ=38,84(4)) with [Pd 2Namine OPO3 Cl] chromophore and a [Pd(HL3)(NH3)2]- complex (lgβ=43,14(2)) and [Pd(L3)(NH3)2]2- complex (lgβ=34.91(2)) with [Pd 3Namine OPO3] chromophore.

scholarly journals Extractable aluminium, iron and manganese in mineral soils: I Dependence of extractability on the pH of oxalate, pyrophosphate and EDTA extractants

1989 ◽  
Vol 61 (2) ◽  
pp. 73-78 ◽  
Author(s):  
Raina Niskanen
Keyword(s):  
Supporting Electrolyte ◽  
Pka Values ◽  
Fe And Mn ◽  
Mineral Soils ◽  
Ph Range ◽  
Iron And Manganese

Al, Fe and Mn in two mineral soils were extracted by 0.05 M and 0.02 M oxalate and pyrophosphate and 0.02 M EDTA solutions the pH of which was adjusted to values ranging from 1.7 to 11.0. The extractability of metals tended to decrease as the pH rose and as the deprotonation of extractant acid, expressed as pKa values, progressed. The reduction in extractability of metals by oxalate was rather steep at pH > 4, whereas the extractability by pyrophosphate remained moderate at a wider pH range. The extractability of metals by EDTA (pH 3.6—7.3) was lower than that by oxalate and pyrophosphate. Extractability was lower in the absence of the studied oxyacid anions and with 0.01 M KCI as the supporting electrolyte at a pH between 2 and 11 than in their presence.

scholarly journals Fluorescent pH probes for alkaline pH range based on perylene tetra-(alkoxycarbonyl) derivatives

2020 ◽  
Vol 13 (6) ◽  
pp. 5900-5910
Author(s):  
Fengxia Zhang ◽  
Wenyao Dong ◽  
Yongshan Ma ◽  
Tianyi Jiang ◽  
Bing Liu ◽  
...  
Keyword(s):  
Alkaline Ph ◽  
Ph Range ◽  
Ph Probes

277. Equine chorionic gonadotrophin isoform composition in commercial products compared with isoform composition in pregnant mare plasma

2008 ◽  
Vol 20 (9) ◽  
pp. 77
Author(s):  
U. A. Ciller ◽  
I. M. Ciller ◽  
J. R. McFarlane
Keyword(s):  
Liquid Phase ◽  
Chorionic Gonadotrophin ◽  
The Other ◽  
Acidic Ph ◽  
Plasma Samples ◽  
Glycoprotein Hormone ◽  
Livestock Industry ◽  
Horse Plasma ◽  
Ph Range ◽  
High Degree

It is well documented that there is considerable batch to batch variation in the activity of commercial preparations of gonadotrophins. These products are used in a variety of assisted reproductive procedures in the livestock industry, consequently this high degree of variation between products and batches adds to the already considerable between animal variations in response to the treatment. Equine chorionic gonadotrophin (eCG) is a heterodimeric glycoprotein hormone secreted by the placental endometrial cups during the first third of gestation in the horse. Plasma is harvested from pregnant mares between 40–90 days of gestation and the eCG isolated and used to formulate commercial preparations. Previous research has shown that eCG like the other gonadotrophins is a highly heterogeneous molecule with significant differences in bioactivity between isoforms. The aim of this study was to determine whether significant differences in isoform composition exist between various commercial preparations of eCG (n = 15), and how this compares with the isoform composition found in plasma (n = 23). Concentrations of eCG were determined using a competitive eCG ELISA. Liquid phase iso-electric focusing was used to fractionate plasma and the commercial preparations into 10 pH ranges from pH 3.0 to pH 10.0. Data from the 10 fractions were grouped into acidic (pH 3.0–5.1), intermediate (pH 5.2–7.9), or basic (pH 8.0–10.0) isoform categories for analysis. Immunoactivity between commercial eCG products ranged from 44% to 362% of stated bioactivity. Iso-electric focusing showed that the majority of the immunoactivity (92%) of the commercial preparations was found in the acidic fractions (pH 3.0–5.1), and in particular in the pH range 3.0–3.8. This contrasted starkly with isoform profiles found in pregnant mare plasma samples which showed a much greater spread across all 3 pH ranges. In summary, the isolation processes of commercial eCG preparations appears to selectively favour the acidic isoforms of eCG.

Two Elution Mechanisms of MEP Chromatography

2018 ◽  
Vol 20 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Tsutomu Arakawa ◽  
Masao Tokunaga ◽  
Takuya Maruyama ◽  
Kentaro Shiraki
Keyword(s):  
Hydrophobic Interaction ◽  
Positive Charge ◽  
Hydrophobic Interaction Chromatography ◽  
Normal Operation ◽  
Acidic Ph ◽  
Charge Induction ◽  
Pyridine Group ◽  
Ph Range ◽  
Hydrophobic Charge Induction Chromatography ◽  
Positively Charged

MEP (mercapto-ethyl-pyridine) HyperCel is one of the hydrophobic charge induction chromatography (HCIC) resins. Under normal operation, proteins are bound to the MEP resin at neutral pH, at which MEP is not charged, mostly via hydrophobic interaction. MEP has a pyridine group, whose pK is 4.8, and hence is positively charged at acidic pH range. Based on the binding mechanism (i.e., hydrophobic interaction) and the induced positive charge at acidic pH, there may be two ways to elute the bound proteins. One way is to bring the pH down to protonate both MEP resin and the bound protein, leading to charge repulsion and thereby elution. Another way is to use hydrophobic interaction modifiers, which are often used in hydrophobic interaction chromatography, to reduce hydrophobic interaction. Here, we summarize such two possible elution approaches.

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