Ion Pairing in Fast-Exchange Host−Guest Systems:  Concentration Dependence of Apparent Association Constants for Complexes of Neutral Hosts and Divalent Guest Salts with Monovalent Counterions

2003 ◽  
Vol 125 (47) ◽  
pp. 14458-14464 ◽  
Author(s):  
Feihe Huang ◽  
Jason W. Jones ◽  
Carla Slebodnick ◽  
Harry W. Gibson
Keyword(s):  
Concentration Dependence ◽  
Ion Pairing ◽  
Association Constants ◽  
Fast Exchange ◽  
Apparent Association Constants ◽  
Apparent Association

scholarly journals Association of neutral red with micelles and its effect on the pKa

1993 ◽  
Vol 71 (11) ◽  
pp. 1785-1791 ◽  
Author(s):  
Robin K. Dutta ◽  
Subray N. Bhat
Keyword(s):  
Equilibrium Constants ◽  
Sodium Dodecyl ◽  
Surfactant Solution ◽  
Neutral Red ◽  
Association Constants ◽  
Alkyltrimethylammonium Bromides ◽  
Surfactant Solutions ◽  
Constant Ph ◽  
Apparent Association Constants ◽  
Apparent Association

The interactions of neutral red with cationic surfactants, viz., N-hexadecylpyridinium chloride and alkyltrimethylammonium bromides; a nonionic surfactant, viz., Triton X100; and an anionic surfactant, viz., sodium dodecyl sulfate, were investigated spectroscopically. The equilibrium constants for the association of the indicator with the micelles were determined from the apparent association constants at constant pH at 298 K. The effects of the indicator-micelle association on the apparent pKa of the indicator in aqueous surfactant solutions are discussed. It was shown that the apparent pKa of the indicator in cationic surfactant solution can be predicted from knowledge of the indicator-micelle association constant.

Cadmium transport in blood serum

2010 ◽  
Vol 26 (4) ◽  
pp. 195-201 ◽  
Author(s):  
Amir Shokooh Saljooghi ◽  
SJ Fatemi
Keyword(s):  
Human Serum ◽  
Association Constants ◽  
Appreciable Amount ◽  
Binding Assays ◽  
Molar Ratios ◽  
Cadmium Transport ◽  
Decreasing Ph ◽  
Ethanesulfonic Acid ◽  
Apparent Association Constants ◽  
Apparent Association

The binding of Cd2+ to human serum transferrin in 0.1 M N-(2-hydroxyethyl) piperazine-N ′-2-ethanesulfonic acid and 5 mM sodium bicarbonate at pH 7.4 has been studied by difference ultraviolet spectrophotometry. The apparent association constants were found to be 2.61 × 105 M —1 and 8.51 × 104M— 1, respectively. These association constants are pH-dependent, reducing with both increasing and decreasing pH. The apparent pKa values were found to be 4.93 and 5.42. Competitive assays of binding of Cd2+ to transferrin in the presence of citrate and human serum albumin at molar ratios corresponding to those found in normal plasma showed that a considerable amount of Cd2+ was not bound to transferrin. The competitive binding assays indicate that ∼50% of Cd2+ is bound to transferrin, ∼37% to albumin and reminder to citrate. These results therefore suggest that, although transferrin at pH 7.4 is the major Cd 2+-binding component of plasma, an appreciable amount of Cd2+ may be bound to albumin.

Nitrate Selectivity of Ion-Exchange Resins and of Their Model Compounds. I. Conductance Measurements on Benzyltrialkylammonium Salts

1990 ◽  
Vol 43 (12) ◽  
pp. 1983
Author(s):  
BJ Steel ◽  
AS Kayaalp ◽  
T Kurucsev ◽  
AD Ward ◽  
MB Jackson
Keyword(s):  
Aqueous Solution ◽  
Ion Exchange ◽  
Concentration Dependence ◽  
Ion Pairing ◽  
Association Constants ◽  
Ion Exchange Resins ◽  
Methyl Ethyl ◽  
Model Compounds ◽  
Sulfate Salts ◽  
Exchange Resins

The concentration dependence of the conductance in aqueous solution of a series of benzyltrialkylammonium chlorides, nitrates and sulfates was measured. The n-alkyl substituents in this series were methyl, ethyl, propyl , butyl and pentyl. The conductances of the chlorides, nitrates and sulfates fit satisfactorily the electrostatic ion pairing models relevant to 1 : 1 and 1 : 2 electrolytes. The extent of ion pairing is small in all the solutions studied but consistently larger for nitrates and sulfates compared with chlorides. The dependence of the association constants on the alkyl substitutents shows different trends for the monovalent anions compared with the sulfate salts.

scholarly journals Aluminium transport in blood serum. Binding of aluminium by human transferrin in the presence of human albumin and citrate

1991 ◽  
Vol 280 (2) ◽  
pp. 527-532 ◽  
Author(s):  
S J Fatemi ◽  
F H A Kadir ◽  
G R Moore
Keyword(s):  
Human Serum ◽  
Human Albumin ◽  
Association Constants ◽  
Appreciable Amount ◽  
Competitive Binding Assay ◽  
Molar Ratios ◽  
Decreasing Ph ◽  
Apparent Association Constants ◽  
Apparent Association ◽  
Binding Component

The binding of Al3+ by human serum transferrin has been investigated by u.v.-visible difference spectroscopy. In the presence of 25 mM-HCO3- at pH 7.4, the apparent association constants were found to be 1.69 x 10(12) M-1 and 5.36 x 10(11) M-1. These association constants are pH-dependent, reducing with both increasing and decreasing pH. The apparent pKa values were found to be 6.7 and 8.2. Competitive assays of binding of Al3+ to transferrin in the presence of citrate and human serum albumin at molar ratios corresponding to those found in normal plasma showed that a considerable amount of Al3+ was not bound to transferrin. Taking a concentration of 5 microM as a typical value observed for the plasma of patients on haemodialysis [Harris & Sheldon (1990) Inorg. Chem. 29, 119-124] the competitive binding assay indicate that approximately 60% of it is bound to transferrin, approximately 34% to albumin and the remainder to citrate. These results therefore suggest that, although transferrin at pH 7.4 is the major Al(3+)-binding component of plasma, an appreciable amount of Al3+ present in patients on haemodialysis may be bound to albumin.

scholarly journals Interaction of rat α-fetoprotein and albumin with polyunsaturated and other fatty acids: Determination of apparent association constants

FEBS Letters ◽  
1989 ◽  
Vol 250 (1) ◽  
pp. 22-24 ◽  
Author(s):  
Alberto Anel ◽  
Miguel Calvo ◽  
Javier Naval ◽  
María Iturralde ◽  
María A. Alava ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Association Constants ◽  
Apparent Association Constants ◽  
Apparent Association
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