Separation of plasma protein fractions by continuous-flow paper electrophoresis using a volatile buffer

Aronson, Ruth F.; Lubash, Glenn D.; Rubin, Albert L.

doi:10.1016/0003-2697(62)90091-x

Cited by 4 publications

(1 citation statement)

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“…The plasma was first dialyzed against 2 liters of triethylamine-acetic acid buffer at a pH of 9.0, and the dialysate was used in the electrophoretic run (10), which was carried out at 600 v and 95 ma while the plasma was applied to the paper at the rate of 1.5 ml/hour. 30 precipitin arc corresponding to albumin and no evidence of other plasma proteins.…”

Section: Methodsmentioning

confidence: 99%

Binding of digitoxin and some related cardenolides to human plasma proteins

Lukas¹,

Martino²

1969

J. Clin. Invest.

136

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A B S T R A C T Tritium-labeled digitoxin, digitoxigenin, digoxin, and digoxigenin of established purity and chemcal authenticity were used to study the binding of these compounds to human plasma proteins. 97% of digitoxin in plasma was nondialyzable. Continuous flow paper electrophoresis of plasma containing digitoxin and dialysis experiments in which human serum albumin competed for the glycoside with plasma or plasma protein fractions demonstrated that digitoxin was almost exclusively bound by albumin. Equilibrium dialyses revealed that the interaction was characterized by a single binding site on the albumin molecule and an association constant of 9.62 X 10' liter/mole at 370C. At 1VC the association constant was 4.64 X 10' liter/mole. The interaction therefore was endothermic; the gain in enthalpy of 3.5 kcal/mole and the free energy change of -7.06 kcal/ mole was derived from a large change in entropy of 33.8 cal/mole per 'K. The direction of these thermodynamic changes suggested the formation of a hydrophobic bond between digitoxin and albumin. Quenching of the fluorescence of albumin by digitoxin indicated that the conformation of albumin was altered by the binding process.Digitoxigenin, its mono-and didigitoxosides, digoxin, and digoxigenin competed with digitoxn for its binding site on albumin. The affinity of the mono-and didigitoxosides for the site was equal to that of digitoxin, but that of digitoxigenin was only one-third as great. The ability of the digitoxose residues of the glycosides to enhance binding to albumin was also observed with digoxin, Presented in part at the 28th Scientific Sessions of the American Heart Association, Miami Beach, Fla., 16 October 1965.Dr. De Martino was formerly a Postdoctoral Research Fellow of the National Heart Institute.Received for publication 15 November 1968 and in revised form 6 February 1969. which was more extensively bound by the protein than digoxigenin.At concentrations of 2 jg/ml or less in plasma, only 23% of digoxin was bound. Albumin, which interacted with digoxin with an apparent association constant of 9 X 102 liter/mole at 370C, was entirely responsible for the binding. Lowering the temperature from 370 to 1VC decreased the fraction of digoxin bound to albumin by two-thirds.The marked difference in avidity of digitoxin and digoxin for serum albumin is reflected by the higher plasma concentrations, lower rate of urinary excretion, and longer half-time of digitoxin as compared to those of digoxin when these compounds are administered to man.

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Section: Methodsmentioning

confidence: 99%

Binding of digitoxin and some related cardenolides to human plasma proteins

Lukas¹,

Martino²

1969

J. Clin. Invest.

136

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Intestinal versus hepatic contribution to circulating triglyceride levels

Cenedella

Crouthamel

Mengoli

1974

Lipids

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Using intravenous injected [2‐3H] glycerol, measurements wee made of the kinetics of appearance and disappearance of circulating [3H] labeled triglyceride in rats fed a fat free diet containing either no orotic acid (controls) or 2% orotic acid. Following injection of [3H] glycerol, more time is required for the initial appearance of [3H] triglyceride in the circulation of orotic acid treated rats than controls. The sustained entry of triglyceride into the circulation of orotic acid fed rats was only one‐half times as rapid as that seen for control rats. Ca. 10% as much [3H] triglyceride entered the circulation of the orotic acid treated rats as compared with controls. However, the clearance of [3H] triglyceride from the circulation of the orotic acid fed rat was only ca. one‐half times as rapid as that of the control rat. This apparently is due to differences between the lipoproteins produced by the intestines and liver, rather than to changes in the ability of the orotic acid fed animal to clear lipoprotein‐triglyceride from the circulation. Labeled lipoproteins taken from controls and injected into orotic acid treated rats were cleared from the circulation more than twice as rapidly as those taken from orotic acid fed rats and injected into controls. Considering the measured levels of plasma triglyceride synthesis and the slower turnover of the triglycerides produced by the orotic acid fed rat, the findings of this study indicate that the intestines supply 20% or more of the total plasma triglyceride in the absence of dietary fat.

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