scholarly journals THE MECHANISM BY WHICH TRIVALENT AND TETRAVALENT IONS PRODUCE AN ELECTRICAL CHARGE ON ISOELECTRIC PROTEIN

1922 ◽  
Vol 4 (6) ◽  
pp. 741-757 ◽  
Author(s):  
Jacques Loeb
Keyword(s):  
Aqueous Solution ◽  
Osmotic Pressure ◽  
Positive Charge ◽  
Complex Anion ◽  
Complex Cation ◽  
Depressing Effect ◽  
Low Concentrations ◽  
Direct Measurements ◽  
Trivalent Cations ◽  
Positively Charged

1. Experiments on anomalous osmosis suggested that salts with trivalent cations, e.g. LaCl3, caused isoelectric gelatin to be positively charged, and salts with tetravalent anions, e.g. Na4Fe(CN)6, caused isoelectric gelatin to be negatively charged. In this paper direct measurements of the P.D. between gels of isoelectric gelatin and an aqueous solution as well as between solutions of isoelectric gelatin in a collodion bag and an aqueous solution are published which show that this suggestion was correct. 2. Experiments on anomalous osmosis suggested that salts like MgCl2, CaCl2, NaCl, LiCl, or Na2SO4 produce no charge on isoelectric gelatin and it is shown in this paper that direct measurements of the P.D. support this suggestion. 3. The question arose as to the nature of the mechanism by which trivalent and tetravalent ions cause the charge of isoelectric proteins. It is shown that salts with such ions act on isoelectric gelatin in a way similar to that in which acids or alkalies act, inasmuch as in low concentrations the positive charge of isoelectric gelatin increases with the concentration of the LaCl3 solution until a maximum is reached at a concentration of LaCl3 of about M/8,000; from then on a further increase in the concentration of LaCl3 diminishes the charge again. It is shown that the same is true for the action of Na4Fe(CN)6. From this it is inferred that the charge of the isoelectric gelatin under the influence of LaCl3 and Na4Fe(CN)6 at the isoelectric point is due to an ionization of the isoelectric protein by the trivalent or tetravalent ions. 4. This ionization might be due to a change of the pH of the solution, but experiments are reported which show that in addition to this influence on pH, LaCl3 causes an ionization of the protein in some other way, possibly by the formation of a complex cation, gelatin-La. Na4Fe(CN)6 might probably cause the formation of a complex anion of the type gelatin-Fe(CN)6. Isoelectric gelatin seems not to form such compounds with Ca, Na, Cl, or SO4. 5. Solutions of LaCl3 and Na4Fe(CN)6 influence the osmotic pressure of solutions of isoelectric gelatin in a similar way as they influence the P.D., inasmuch as in lower concentrations they raise the osmotic pressure of the gelatin solution until a maximum is reached at a concentration of about M/2,048 LaCl3 and M/4,096 Na4Fe(CN)6. A further increase of the concentration of the salt depresses the osmotic pressure again. NaCl, LiCl, MgCl2, CaCl2, and Na2SO4 do not act in this way. 6. Solutions of LaCl3 have only a depressing effect on the P.D. and osmotic pressure of gelatin chloride solutions of pH 3.0 and this depressing effect is quantitatively identical with that of solutions of CaCl2 and NaCl of the same concentration of Cl.

XXIV.—The Action of Salts of Polynuclear Bases on Colloidal Suspensions and on the Electro-capillary Curve

1930 ◽  
Vol 49 ◽  
pp. 300-312
Author(s):  
J. A. V. Butler ◽  
W. O. Kermack
Keyword(s):  
Colloidal Particles ◽  
Positive Charge ◽  
Colloidal Suspensions ◽  
Unexpected Result ◽  
Low Concentrations ◽  
The Right ◽  
The Cost ◽  
Possible Cause ◽  
Positively Charged ◽  
Lyophobic Sols

Summary1. Salts of 5:6-benz-4-carboline and its derivatives precipitate colloidal gum benzoin and other negatively charged lyophobic sols at comparatively low concentrations, but at considerably higher concentrations they do not bring about flocculation of these colloids but confer a positive charge on the colloidal particles. These effects are similar to those observed with many dyestuffs.2. The effect of the simultaneous presence of benzcarboline salts and of gelatin of pH 4·6 and pH 7·0 has been examined. The presence of small quantities of gelatin appears markedly to decrease the adsorption of benzcarboline ions.3. The effect of various benzcarboline salts on the electro-capillary curve of mercury has been determined. In presence of small concentrations (M/20000) of these salts the maximum of the electro-capillary curve occurs to the right of that of the primitive (negative polarisation of the mercury), and the greatest fall in surface tension occurs to the left of the maximum of the primitive (positive polarisation of the mercury).4. These results indicate high adsorption of benzcarboline ions even on a positively charged surface. The possible cause of this unexpected result is discussed.The authors wish to express their indebtedness for a grant from Imperial Chemical Industries, Ltd., which defrayed in part the cost of the apparatus employed in the electro-capillary experiments. They also wish to express their thanks to Mr W. Leeper and Mr W. Spragg for valuable assistance.

Positive charge modifications alter the ability of XIP to inhibit the plasma membrane calcium pump

1996 ◽  
Vol 271 (3) ◽  
pp. C736-C741 ◽  
Author(s):  
W. Xu ◽  
C. Gatto ◽  
M. A. Milanick
Keyword(s):  
Plasma Membrane ◽  
Positive Charge ◽  
Calcium Pump ◽  
Inhibitory Peptide ◽  
Ca Pump ◽  
Contact Points ◽  
Plasma Membrane Calcium Pump ◽  
Peptide Analogues ◽  
Positively Charged

Exchange inhibitory peptide (XIP; RRLLFYKYVYKRYRAGKQRG) is the shortest peptide that inhibits the plasma membrane Ca pump at high Ca (A. Enyedi, T. Vorherr, P. James, D. J. McCormick, A. G. Filoteo, E. Carafoli, and J. T. Penniston, J. Biol. Chem. 264: 12313-12321, 1989). Sulfosuccinimidyl acetate (SNA)-modified XIP does not inhibit the Ca pump; SNA neutralizes the positive charge on Lys at positions 7, 11, and 17. Peptide 2CK-XIP (RRLLFYRYVYRCYCAGRQKG) inhibits the pump, but the iodoacetamido-modified peptide does not inhibit. Three peptide analogues, in which 7, 11, and 17 were Ala, Cys, or Lys, inhibited about as well as XIP. SNA modification of these analogues (each with 1 Lys) did not inhibit. SNA modification of 2CK-XIP results in a peptide that does not inhibit; thus position 19 is important. Our results suggest that it is critical that position 19 be positively charged, that positions 7, 11, and 17 are important contact points between XIP and the Ca pump (with at least one positively charged), and that, whereas it is not essential that residues 12 and 14 be positive, they cannot be negative.

Inerte Amminkomplexe als mehrwertige Kationsäuren in wäßriger Lösung / Inert Ammine Complexes as Multivalent Cationic Acids in Aqueous Solution

1980 ◽  
Vol 35 (9) ◽  
pp. 1096-1103 ◽  
Author(s):  
Matthias Kretschmer ◽  
Lutwin Labouvie ◽  
Karl-W. Quirin ◽  
Helmut Wiehn ◽  
Ludwig Heck
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Spectrophotometric Method ◽  
Complex Cation ◽  
Aqua Ligand ◽  
Second Step ◽  
Acidity Constants ◽  
Ammine Complexes ◽  
Temperature Variations ◽  
Enthalpy Changes

Acidity constants of ammine complexes of tetravalent platinum in aqueous solutions have been determined by a spectrophotometric method at very low ionic strengths and extrapolated to zero ionic strength. Temperature variations of pK-values (25 °C and 50 °C) yield thermodynamic parameters for two successive deprotonation steps of hexaammineplatinum(IV), pentaamminechloroplatinum(IV), and tris(ethylenediamine)pla- tinum(IV) complexes and for the deprotonation of pentaammineaquacobalt(III) ion.The enthalpy changes for the first and second steps are similar and range from 50 to 75 kJ/mole while for the aqua ligand of Co(III) 33 kJ/mole are found. The very large dif­ference in the entropy changes (about 70 to 80 J/K mole for the first step and -10 to + 20 J/K mole for the second step) is interpreted by a model of solvation change. The primary hydration sphere of strongly oriented and immobilized water dipoles around the highly charged complex cation is transformed to a hydrogen-bonded solvation sheath when the electric field of the complex is weakened upon release of the first proton.

Liudongshengite, Zn4Cr2(OH)12(CO3)·3H2O, a new mineral of the hydrotalcite supergroup, from the 79 mine, Gila County, Arizona, USA

2021 ◽  
Vol 59 (4) ◽  
pp. 763-769
Author(s):  
Hexiong Yang ◽  
Ronald B. Gibbs ◽  
Cody Schwenk ◽  
Xiande Xie ◽  
Xiangping Gu ◽  
...  
Keyword(s):  
Unit Cell ◽  
New Mineral ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
New Mineral Species ◽  
General Chemical ◽  
Perfect Cleavage ◽  
Mohs Hardness ◽  
Trivalent Cations ◽  
Positively Charged

ABSTRACT A new mineral species, liudongshengite, ideally Zn4Cr2(OH)12(CO3)·3H2O, has been found in the 79 mine, Gila County, Arizona, USA. It occurs as micaceous aggregates or hexagonal platy crystals (up to 0.10 × 0.10 × 0.01 mm). The mineral is pinkish and transparent with white streak and vitreous luster. It is brittle and has a Mohs hardness of ∼1.5, with perfect cleavage on (001). No twinning or parting is observed macroscopically. The measured and calculated densities are 2.95 (3) and 3.00 g/cm3, respectively. Optically, liudongshengite is uniaxial (−), with ω = 1.720 (8), ε = 1.660 (7) (white light). An electron microprobe analysis, combined with the carbon content measured using an elemental combustion system equipped with mass spectrometry, yielded the empirical formula (Zn3.25Mg0.17Cr2.58)Σ6.00(OH)12(CO3)1.29·3H2O, based on (M2+ + M3+) = 6 apfu, where M2+ and M3+ are divalent and trivalent cations, respectively. Liudongshengite belongs to the quintinite group within the hydrotalcite supergroup and is the Cr-analogue of zaccagnaite-3R, Zn4Al2(OH)12(CO3)·3H2O. It is trigonal, with space group Rm and unit-cell parameters a = 3.1111(4), c = 22.682(3) Å, and V = 190.12(4) Å3. The crystal structure of liudongshengite is composed of positively charged brucite-like layers, [M2+1–xM3+x(OH)2]x+, alternating with negatively charged layers of (CO3)2–·3H2O. Compared to other minerals in the quintinite group, liudongshengite is remarkably enriched in M3+, with an M2+:M3+ ratio of 1.33:1. Like zaccagnaite-3R and many other hydrotalcite-type minerals, liudongshengite may also possess polytypes, as a series of synthetic hydrotalcite-type compounds with a general chemical formula [Zn4Cr2(OH)12]X2·4H2O, where X = Cl–, NO3–, or ½ SO42–, but with unit-cell parameters different from those for liudongshengite, have been reported previously.

scholarly journals Bis[tetrakis(pyridin-2-yl)methane-κ3N,N′,N′′]cobalt(II) tetrakis(thiocyanato-κN)cobaltate(II) methanol monosolvate

2014 ◽  
Vol 70 (3) ◽  
pp. m96-m97 ◽  
Author(s):  
Yuya Tsunezumi ◽  
Kouzou Matsumoto ◽  
Shinya Hayami ◽  
Akira Fuyuhiro ◽  
Satoshi Kawata
Keyword(s):  
Complex Anion ◽  
Complex Cation ◽  
Solvent Molecule ◽  
Octahedral Geometry ◽  
Title Complex ◽  
Distorted Octahedral Geometry ◽  
Weak Hydrogen Bond ◽  
Tetrahedral Geometry ◽  
Distorted Tetrahedral Geometry ◽  
Distorted Octahedral

The title complex, [Co(C21H16N4)2][Co(NCS)4]·CH3OH, consists of one [Co{C(py)4}2]2+complex cation [C(py)4= tetrakis(pyridin-2-yl)methane], one [Co(NCS)4]2−complex anion and a methanol solvent molecule. In the cation, the CoIIatom is coordinated by six N atoms of two C(py)4ligands in a distorted octahedral geometry. In the anion, the CoIIatom is coordinated by the N atoms of four NCS−ligands in a distorted tetrahedral geometry. The methanol molecule is disordered and was modelled over three orientations (occupancies 0.8:0.1:0.1). There are two weak hydrogen-bond-like interactions between the methanol solvent molecule and NCS−ligands of the anion [O...S = 3.283 (3) and 3.170 (2) Å].

Thermal and light-induced reduction of the ruthenium complex cation Ru(bpy)33+ in aqueous solution

1984 ◽  
Vol 106 (17) ◽  
pp. 4772-4783 ◽  
Author(s):  
Pushpito K. Ghosh ◽  
Bruce S. Brunschwig ◽  
Mei Chou ◽  
Carol Creutz ◽  
Norman Sutin
Keyword(s):  
Aqueous Solution ◽  
Ruthenium Complex ◽  
Complex Cation

Role of S4 positively charged residues in the regulation of Kv4.3 inactivation and recovery

2007 ◽  
Vol 293 (3) ◽  
pp. C906-C914 ◽  
Author(s):  
Matthew R. Skerritt ◽  
Donald L. Campbell
Keyword(s):  
Positive Charge ◽  
Voltage Sensitivity ◽  
Shaker Channels ◽  
Recovery From Inactivation ◽  
Kv4 Channels ◽  
Charged Residues ◽  
Arginine Residues ◽  
Voltage Sensing Domain ◽  
Positively Charged

The molecular and biophysical mechanisms by which voltage-sensitive K+ (Kv)4 channels inactivate and recover from inactivation are presently unresolved. There is a general consensus, however, that Shaker-like N- and P/C-type mechanisms are likely not involved. Kv4 channels also display prominent inactivation from preactivated closed states [closed-state inactivation (CSI)], a process that appears to be absent in Shaker channels. As in Shaker channels, voltage sensitivity in Kv4 channels is thought to be conferred by positively charged residues localized to the fourth transmembrane segment (S4) of the voltage-sensing domain. To investigate the role of S4 positive charge in Kv4.3 gating transitions, we analyzed the effects of charge elimination at each positively charged arginine (R) residue by mutation to the uncharged residue alanine (A). We first demonstrated that R290A, R293A, R296A, and R302A mutants each alter basic activation characteristics consistent with positive charge removal. We then found strong evidence that recovery from inactivation is coupled to deactivation, showed that the precise location of the arginine residues within S4 plays an important role in the degree of development of CSI and recovery from CSI, and demonstrated that the development of CSI can be sequentially uncoupled from activation by R296A, specifically. Taken together, these results extend our current understanding of Kv4.3 gating transitions.

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