Human Plasma Albumin Research Articles

Transport of lysolecithin by albumin in human and rat plasma

Lysolecithin comprises 9.6 and 21.5% of the phospholipids of the plasma of man and rat, respectively. Ultracentrifugal and gel filtration studies showed that the major portion of the lysolecithin is not found together with the other phospholipids in the plasma lipoproteins. By zone electrophoresis, gel filtration, and ammonium sulfate fractionation, it was found that lysolecithin was consistently associated with albumin fractions. Immunoelectrophoretically homogeneous rat albumin was prepared. It contained 0.5 mg of lipid phosphorus per g of protein; 98.3% of this lipid was lysolecithin. It is concluded that lysolecithin is transported in plasma bound to albumin.

The Antagonistic Effect of Human Plasma Albumin on the Insulin Stimulated Glucose Uptake of the Isolated Rat Diaphragm

AbstractJervell, J., The antagonistic effect of human plasma albumin on the insulin stimulated of glucose uptake of the isolated rat diaphragm. Acta physiol. scand. 1965, 65, 33–44. — Albumin isolated by several different procedures antagonized the effect of insulin on the glucose uptake of the isolated rat hemidiaphragm. The antagonism was still present after the pH reducing effect of the albumins had been corrected. A decrease in pH was also found to have some insulin‐antagonistic effect. There was no correlation between the antagonistic effect and the free fatty acid content of the albumins, and adding palmitate to a nonantagonistic albumin did not increase its antagonistic activity. The antagonistic effect cannot he explained by the calcium and magnesium binding properties of the albumin.

BINDING OF CALCIUM BY HUMAN PLASMA PROTEINS UNDER SIMULATED PHYSIOLOGIC CONDITIONS.

The binding of calcium to human plasma albumin, alpha, beta, and gamma globulins was studied with the aid of an ultracentrifuge. The amount of calcium bound to these separated proteins was determined in solutions with electrolyte concentrations and pH within physiological ranges. The total calcium concentration was 2.35–2.90 mm/liter H2O and the total protein concentration was 3.91–4.29 g/100 ml H2O. In these solutions no significant differences were found for the binding of calcium (expressed as mm Ca++ bound per gram protein) by albumin, alpha, and beta globulins; the average values obtained were, respectively, 0.016, 0.018, and 0.023. Significantly less calcium was bound by gamma globulin; 0.009 mm/gram. The pH was varied between 7.200–7.550 and the sodium chloride concentration between 114–157 mEq Na per liter. These changes did not measurably affect the amount of calcium bound to albumin. protein-bound calcium; ultracentrifugation and determination of protein-bound calcium; plasma globulin-bound calcium; plasma albumin-bound calcium Submitted on July 2, 1963

Role of glutathione in the catheptic hydrolysis of plasma albumin

Human plasma albumin and S 35 -labeled glutathione mixtures yield radioactive polypeptides when incubated with cathepsin at pH 3.6. The results show that substantial amounts of glutathione are incorporated in the products of hydrolysis of albumin. These results and those previously reported concerning the formation of albumin-GSH mixed disulfides at low pH suggest that GSH plays an important role in modifying the substrate and in rendering it susceptible to catheptic hydrolysis. The implications of these findings and their possible significance in intracellular protein catabolism are discussed.

A Structural Transformation in Bovine and Human Plasma Albumins in Alkaline Solution as Revealed by Rotatory Dispersion Studies

A Structural Transformation in Bovine and Human Plasma Albumins in Alkaline Solution as Revealed by Rotatory Dispersion Studies

Separation of polypeptides bound by albumin in human plasma.

THE role of plasma albumin in maintaining oncotic pressure is generally known, but its significance as a potent binder of other substances is little appreciated. In addition to binding and transporting materials such as steroids, bilirubin, fatty acids, hormones, and dyes1, albumin may similarly distribute many biologically important polypeptides. Therefore, the hypoalbuminaemia of certain disease states, including uraemia, hepatic failure, and chronic infection, may be associated with diminished transport of polypeptides to their sites of action and detoxification.

The interaction of human plasma albumin and reduced glutathione

Human plasma albumin incubated with reduced glutathione (GSH) undergoes reduction and yields a product which possesses the electrophoretic mobility of the plasma α-globulins. This reaction, involving disulfide groups, takes place at pH values ranging from 2.5 to 4.7. No reaction between albumin disulfide groups and GSH occurs at pH 2.0 or at pH values ranging from 5.0 to 9.0. Both reduction and electrophoretic modification of plasma albumin exhibit pH optima in the vicinity of 3.6 and yield similar curves when plotted against pH. These curves are also similar to that of the activity of intracellular proteinases activated by GSH. The behavior of albumin toward GSH at various pH values, in the absence and in the presence of urea, indicates that both the reactivity of GSH and the accessibility of the protein disulfide bonds are limiting factors in the reaction. Evidence is presented that mixed disulfides are formed during the process of reduction of plasma albumin by GSH. These disulfides are stable at low pH and readily decompose in slightly alkaline solution. The possible significance of the albumin-GSH reaction in intracellular protein catabolism is discussed.

Depression of plasma albumin by steroid therapy.

SummaryThe effect of steroid therapy on human plasma albumin has been studied. Daily oral ingestion of 5 mg of norethynodrel and 0.75 mg of ethynylestradiol-3-methyl ether depressed albumin levels by 20.9% (p < 0.002). A possible relationship of plasma albumin to the effectiveness of estrogenic therapy in older subjects recovering from a myocardial infarction is noted.

Statistical evaluation of the rotatory dispersion parameters for helical polymers and proteins: Two proposed methods and their application to data on polyglutamic acid and plasma albumin

Two statistical methods for the evaluation of the best values of the parameters of the Moffitt equation, λ 0, a 0, and b 0, are proposed. The first is based on the maximization of the F ratio of the linear regression term to the residual term in the Moffitt-Yang form of the equation. The second is based on the minimization of the quadratic term in an extended form of this equation. Both methods are readily programmed for a digital computer. The usefulness of these equations has been demonstrated by analysis of a large number of dispersion curves obtained on polyglutamic acid through the region of the helix-coil transition and on bovine and human plasma albumins as function of pH. The results clearly show the inability of the simple Drude equation to fit dispersion data on native plasma albumin even over a relatively narrow range of wavelengths, and the remarkable ability of the Moffitt equation to fit data over a much broader range. It is shown that the best values of the dispersion parameters are not altered by extending the dispersion data from 300 mμ down to 240 mμ; however, precision is actually lost by this extension of the data. The best value of λ 0 is shown to be constant within experimental error throughout almost the entire helix-coil transition in polyglutamic acid. The best value of λ 0 is not affected by omission of the correction for solvent refractive index provided that the dispersion of refractive index is simple; however, the best values of a 0 and b 0 are appreciably affected by omission of this correction.

Studies on the binding of cortisol-4-14C by human leucocytes in vitro.

ABSTRACT The amount of cortisol-4-14C bound by human leucocytes in a non-protein balanced salt solution was found to have a linear relationship to the concentration of cortisol-4-14C for a given number of leucocytes, and a linear relationship to the number of leucocytes for a given concentration of cortisol-4-14C. The binding was not affected by 10−3 m concentrations of arsenate, cyanide, fluoroacetate, dinitrophenol, fluoride, methylene blue, malonate, hydroxylamine or semicarbazide. The binding of cortisol-4-14C by leucocytes was found to be temperature dependent. At 0° C, no binding of cortisol-4-14C was detected. From 10° to 80°, each 10° rise resulted in an approximately two fold increase in amount of cortisol-4-14C bound, but no further increase occurred between 80° and 100°. Experiments in which leucocytes were exposed to various specific temperatures without cortisol, and then incubated with cortisol-4-14C at 37° revealed that exposure to lower temperatures had no effect on the uptake of cortisol-4-14C at 37°, but that exposure to higher temperatures had increased the binding of cortisol-4-14C at 37°. The addition of either human plasma or human serum albumin to the incubation medium markedly reduced the uptake of cortisol-4-14C by the leucocytes. Approximately 2/3 of the cortisol-4-14C (or metabolite) was removed upon incubation for 30 minutes at 37° C with either Hanks's solution (non-protein), plasma or serum albumin.

Identification of a plasma material stimulating haemoglobin synthesis in vitro

Previous work had shown the presence in dog plasma and in a partially purified preparation of human plasma albumin of a material which stimulates haem biosynthesis in two synthesis in vitro: in a haemolysate of chicken red blood cells and in dog blood rich in reticulocytes. The present work deals with the purification and identification of this material. A study of the behaviour of the stimulating materials from these two sources on various ion-exchange resins indicated that they had similr properties and strongly suggested that the two materials might be identical. Purification of the active material from partially purified plasma albumin led to the isolation of a highly active fraction having the properties of citric acid. Citric acid was shown to stimulate haem biosynthesis in both systems. The dog plasma was further investigated and shown to contain citric acid and the stimulation of haemoglobin biosynthesis produced in the dog reticulocyte system was closely related to the citrate content of the plasma. It was concluded that citric acid was the principal stimulating factor present in the plasma albumin preparation and in the dog plasma. Citric acid exerted its stimulating effect at a stage in the haem biosynthetic sequence prior to the formation of σ-amino-laevulic acid.

Uncoupling of oxidative phosphorylation and inhibition of ATPP i exchange by a substance from insect mitochondria

Human and bovine serum or plasma albumins, and to a smaller degree β-lactoglobulin, stimulate oxidative phosphorylation and the ATPP i exchange reaction mitochondria from larvae of the wax-moth, Galleria mellonella L. (Lepidoptera). This effect has been shown to be due to removal by these proteins of an uncoupling agent that is present in isolated insect mitochondria. It has been demonstrated that this uncoupling agent contains fatty acids, of which palmitic, stearic, oleic, linoleic and linolenic acids have been identified by paper chromatography.

The biological behaviour of normal and denatured human plasma albumin

In studying human plasma protein metabolism with labelled proteins, it is important to know that each preparation of tagged protein behaves in the same way as native unlabelled protein. Two biological tests have been devised for detecting the presence of protein molecules that have been so altered that they are handled differently in the body. The first takes advantage of the retention of grossly denatured protein by organs: in this test most of the denatured protein can be found in the liver of the rat 15 min after intravenous injection. In the second test rabbits rendered tolerant to human plasma proteins, are injected intravenously with the labelled protein and the half life measured. Deliberately denatured albumin has been shown to be eliminated more rapidly than normal protein over a period of a week or more.

Hyperlipemia and hemolysis. III. Acceleration of oleate lysis of human erythrocytes by homologous plasma.

Summary1. Pretreatment of fatty acid with human plasma, plasma albumin or globulin, unesterified cholesterol, or cyanide retards or prevents hemolytic activity. Once lytic quantities of fatty acid are bound by human erythrocytes, the above substances reverse their protective activity and accelerate hemolysis. 2. Plasma and plasma factors appear to accelerate intrinsic oleate hemolytic activity rather than act via a secondary superimposed lytic mechanism; the mode of cyanide action is unknown. 3. The oleate hemolysis protective and accelerating properties of human plasma can be inhibited progressively and simultaneously by pretreatment with oleate. Both mechanisms appear to depend upon plasma ability to bind fatty acid. 4. The intensity of oleate hemolysis acceleration by human plasma or plasma fractions is not uniform. Variations can be attributed to differences in fatty acid binding capacities and to inhibitors which possess unesterified fatty acid activity. 5. A hypothesis is suggested for linking incre...

Albumin from heated human plasma. V. Denaturation kinetics: Influence of ionic strength

The first-order rate of loss of solubility of human plasma albumin has been determined at 65.1 °C., within the pH range from 3.5 to 5.1, as a function of ionic strength from 0.002 to 0.02 μ. Below pH 4.7 the rate increases with increase in ionic strength. Above pH 4.7 the opposite effect is noted. This influence of ionic strength is consistent with a primary salt effect related to the total net charge of the protein molecule. The stability of plasma albumin against insolubilization increases with decrease in pH, a trend which follows the tendency of this protein to expand in acid medium, especially at low ionic strength.

Competition between human plasma albumin and globulins for estradiol and sodium estrone sulfate.

Equilibrium ratio determinations of estradiol and sodium estrone sulfate distributed between human red cells and solutions of human plasma albumin, fraction IV-1, or fraction IV-4 of Cohn were made at 38°C and ionic strength of 0.155. The albumin contents of the IV-1 and IV-4 fractions were analyzed by 26% sodium sulfate fractionation. When the influence of the albumin in fractions IV-1 and IV-4 was estimated on the basis of the performance of pure albumin solution, the influence of the globulins was small even on a molar basis. The red cell:albumin ratio, using a physiologic albumin concentration, was nearly the same as the endogenous ratio previously obtained for last trimester human red cells: serum. It is concluded that albumin is responsible for 90% or more of the orientation in human plasma of the estrogens studied.

CLINICAL STUDIES ON PLASMA ONCOTIC PRESSURE AND BLOOD WATER CONTENT

Plasma oncotic pressure and blood water content were studied clinically from the viewpoint of edema pathogenesis.The conclusions were as follows:1) Three components of oncotic pressure, namely, true oncotic pressure of protein particles, Donnan's pressure and pressure from swelling of protein colloids were studied theoretically. Also isolation of human plasma albumin and γ-globulin were performed by Howe's method and equations for calculating the oncotic pressure of each collid were established, namely A=36x1.33 for albumin and G=6x1.60 for γ-globulin. (x: concentration of colloids gm/dl)2) Clinical studies of 186 cases suffering from diseases producing edema (such as heart disease, renal disease, liver disease, anemia, carcinoma etc.) have been carried out, especially concerning edema pathogenesis.Most conspicuous changes of blood water content have been shown in the cases of heart disease, nephrosis and anemia, namely in the cases of heart disease both plasma and corpuscle water were moderately increased, and in the cases of nephrosis remarkable increase of plasma water was present but not in corpuscle water. However in the cases of anemia, water content of corpuscle was only increased without the accompaning increase of plasma water.Oncotic pressure of plasma of such cases was also studied in its relationship with the plasma protein concentration and its fractions. Most remarkable decrease of oncotic pressure, plasma protein and albumin level has been shown in the cases of nephrosis, also remarkable decrease of oncotic pressure with normal plasma protein concentration but with low albumin and high γ-globulin level has been shown in the cases of liver cirrhosis.3) General relationship between plasma oncotic pressure and concentration of protein fractions was studied and a new equation for calculating the oncotic pressure from the concentration of plasma protein fractions has been established and examined, namely.P=90(Al+1/3α-gl+1/4γ-gl)-75

Experimental studies in metal cancerigenesis. V. Interaction of Cr III and Cr VI compounds with proteins

The binding of Cr III and Cr VI, as represented by chromic acetate and potassium chromate, to egg proteins and human plasma proteins has been investigated by dialysis and electrophoretic techniques. Cr VI was shown by dialysis and by electrophoretic and precipitation experiments to be bound by egg albumin in decreasing amounts as the pH changed from 4 to 7.35. Pooled and individual human plasma samples bound two to three times as much Cr VI at pH 7.35 as did egg albumin. The binding of Cr VI to egg albumin at pH 4 could be demonstrated by paper electrophoresis but could not be demonstrated by this technique at pH 7.35 with either egg albumin or human plasma. The results suggest an essentially electrostatic type of binding [cf. (Refs. 17, 18)] increasing as the positive charge on the proteins increases. Solutions of protein containing from 100 to 1000 μg. Cr VI/ml. were self-sterilizing from pH 4 to 8. Reduction of Cr VI occurred on long contact with sterile protein solutions up to at least pH 6.4. Cr III, which in the form of chromic acetate at pH 7.35 exists in positive, negative, and neutral complexes of low charge (8), was bound by both human plasma and egg albumin. The complexes formed from chromic acetate at all pH's studied produced no visible reaction with any of the protein components [cf. (18)] and were not self-sterilizing at the higher pH's. Difficulties due to hydrolysis, olation and aggregation to form polynuclear Cr III complexes in aqueous solutions of Cr III salts are discussed and data presented showing the effects of these changes on apparent binding as evaluated by dialysis techniques. Conditions permitting differentiation between bound Cr III and nondiffusible Cr III are presented. Dialysis data indicated a decreased binding of chromium in lipemic plasmas in the limited number of cases studied. At pH 7.35, neither Cr III nor Cr VI in the concentration range 10 −4–10 −2 M significantly altered the electrophoretic patterns of egg elbumin components. Cr VI under similar conditions produced no significant effect on human plasma proteins. Cr III likewise had no effect at the lower concentrations; but at the higher concentration levels produced a small amount of a new component of unknown nature migrating ahead of human serum albumin. Paper electrophoresis at pH 7.35 and μ = 0.05 indicated binding of Cr III to human plasma proteins and egg albumin. The binding appeared to increase with time of contact.

Albumin from heated human plasma. IV. Diffusion studies

The diffusion of human and bovine plasma albumin was studied by the Rayleigh-Calvet-Philpot interference fringe method. Analysis of the boundary shapes revealed heterogeneity for most of the preparations of human albumin. The purity of the preparations as indicated by electrophoresis ranged from 91.5 to 99% and was correlated with the heterogeneity measured by diffusion in a semiquantitative manner. At pH 7.30 the diffusion coefficient, D 0, w , of the purest preparations of human albumin obtained from heated plasma or isolated by electrophoresis was found to be 3.2 (±0.1) × 10 −7 with solutions containing 0.7 and 1.0 g./100 ml. D 0, w for 0.1 N KCl was 9.31 (±0.02) × 10 −6 and for a 0.7% solution of crystalline BPA, at pH 4.55 was 2.940 (±0.003) × 10 −7.

Albumin from heated human plasma. III. Denaturation kinetics: Influence of acetate ions

The influence of acetate ions on the denaturation of human plasma albumin has been studied by measuring the reaction rate as a function of pH and temperature. The process of denaturation follows first-order kinetics with respect to protein concentration and also appears to be first order with respect to acetate. At constant acetate-ion concentration, measurements of the change in the experimental rate of denaturation with pH show that the role of the hydrogen ion in the denaturation process is the same as has been previously determined in the absence of acetate. In the presence of acetate, there is an increase in the value of the dissociation constant for the five key prototropic ionizations which control the stability of the protein. However, the effect of temperature on the p K remains unchanged. At 54.9 °, when acetate is present, there is a marked elevation in the rate of the net denaturation reaction, which occurs when albumin becomes labile as a result of the suppression of three of the key dissociations. At 69.6 °, the rate is found to be greater in the absence of acetate. Thus, the heat of activation for the net denaturation reaction is considerably lower when acetate is present.