Investigation of Ternary Complex Formations of Polyacrylic Acid with Bovine Serum Albumin in the Presence of Metal Ions by Fluorescence and Dynamic Light Scattering Measurements

In this paper, the complex formation of bovine serum albumin (BSA) and polyacrylic acid (PAA) in the presence metal ions at pH = 7 has been examined by using fluorescence and dynamic light scattering measurements. It has been observed that the most stable complexes of polyacrylic acid and bovine serum albumin have occurred in the presence of copper(II) ions. The other ions have the ability to form weak complexes between polyions and bovine serum albumin. To prior characterizing the interaction between bovine serum albumin and polyacrylic acid, the dynamic light scattering technique have been applied to determine the intensity-size distributions of the solutions of bovine serum albumin, polyacrylic acid, and ternary mixtures containing various molar ratios of bovine serum albumin to polyacrylic acid (the molar ratios of bovine serum albumin to polyacrylic acid has been taken equal to 0.5, 1.0, 1.5, 2.0 and 2.5) prepared at different molar ratios of copper(II) ions/acrylic acid unit. When the molar ratio of copper(II) ions to acrylic acid in the ternary mixtures has been lower than and equals to 0.3, two peaks have been observed in the curves of the intensity-size distributions due to contents of free bovine serum albumin and ternary complexes of polyacrylic acid-copper(II)-bovine serum albumin whereas when the molar ratio of copper(II) ions to acrylic acid equals to 0.4, the hydrodynamic diameter has pointed out only one peak. This result indicates that soluble and stable ternary complexes has occurred when the molar ratio of copper(II) ions to acrylic acid has been taken equal to 0.4.     

The binding of flavopiridol to blood serum albumin

Flavopiridol is a potent cyclin-dependant kinase (CDK) inhibitor and is in clinical trials for anticancer treatment. A limiting factor in its drug development has been the high dosage required in human clinical trials. The high dosage is suggested to be necessary because of significant flavopiridol binding to human blood serum. Albumin is the major protein component of blood serum and has been suggested as a likely high affinity binding target. We characterized the binding of human serum albumin to flavopiridol using circular dichroism (hereafter CD). Flavopiridol bound to human serum albumin has a diagnostic CD binding peak at 284 nm. The diagnostic CD binding peak was unobservable for flavopiridol with bovine serum albumin, using the same experimental conditions. However, under higher albumin concentrations a small CD signal is observed confirming, flavopiridol binds to bovine serum albumin as well.     

A stoichiometric analysis of bovine serum albumin-gossypol interactions: a fluorescence quenching study.

The interaction of gossypol with bovine serum albumin, human serum albumin and n-bromosuccinimide-modified bovine serum albumin has been followed by fluorescence quenching measurements. The presence of a high affinity site (association constant K = 2.2 x 10(6) M-1) for gossypol on bovine serum albumin and human serum albumin is indicated. The stoichiometry of binding for the high affinity site was evaluated using Job's method of continuous variation, thereby suggesting the formation of 1:1 complex. Modification of the tryptophan residues on bovine serum albumin does not affect the binding of gossypol to either high or low affinity site of albumin.     

Alteration of immunological properties of bovine serum albumin by covalent attachment of polyethylene glycol.

Methoxypolyethylene glycols of 1900 and 5000 daltons have been attached covalently to bovine serum albumin using cyanuric chloride as the coupling agent. When sufficient polymer is attached, the modified bovine serum albumin appears to lose its immunogenicity in the rabbit and, on intramuscular or intravenous injection, elicits antibodies neither to itself nor to native bovine serum albumin. It does not react with antibodies raised against native bovine serum albumin. Bovine serum albumin to which methoxypolyethylene glycol has been attached exhibits a blood circulating life in the rabbit rather similar to native bovine serum albumin, except that it is not removed from circulation by the eventual development of antibodies. Modified bovine serum albumins which had been iodinated with 125I, or prepared with [14C]cyanuric chloride, were injected intravenously in rabbits. Both labels appeared almost quantitatively in the urine after 30 days. The modified bovine serum albumins showed substantial changes in properties, such as solubility, electrophoretic mobility in acrylamide gel, ion exchange chromatography, and sedimentation, as compared with the unmodified protein.     

A chaperone-mimetic effect of serum albumin on rhodanese

Reactivation of denatured rhodanese (thiosulfate:cyanide sulfurtransferase, EC 2.8.1.1) was found to be aided by the presence of serum albumin. Both the rate and the extent of reactivation of the urea-denatured enzyme were optimal at low rhodanese and moderate serum albumin concentrations. Similarly, stabilization of the sulfurtransferase activity of rhodanese that had been partially unfolded at 40°C was aided by the presence of serum albumin. All the observations are in accord with a model in which enzyme that has been partially refolded from the urea-denatured state or partially unfolded thermally interacts directly with serum albumin in a way that prevents rhodanese self-association. Serum albumin thus acts as a molecular chaperone in these systems.     

Stimulation of triacylglycerol synthesis by intracellular serum albumin

A factor in the supernatant fraction of adipose tissue that stimulates the synthesis of triacylglycerols by microsomes has been identified as serum albumin. The stimulatory effect is directly proportional to the ratio of fatty acids bound to the albumin. Small amounts of serum albumin appear to be inside the adipocytes and albumin can be taken up by isolated adipocytes. The rate of uptake of fatty acids by the adipocytes is more than 1000 times the uptake of serum albumin. This difference provides counter-evidence for the proposal that serum albumin might function in the vesicular transport of fatty acids.     

Structure-activity features of serum albumin in athletes under physical load

By circular dichroism the secondary structure of serum albumin has been studied in organism of high-qualified volleyball-sportsmen. It has been determined that changes in percentage correlation of alpha- and beta-structures of sportsmen serum albumin were combined with decrease of protein reserve functional activity and with its intensified liganding by substance of lipid and carbohydrate nature.     

Palmitate-binding, serum albumin-like proteins in salmonids

There has been considerable controversy over the existence of serum albumin in fish. One of the physiological functions of albumin is to bind free fatty acids. This characteristic was used to screen the plasma of seven species of salmonids. Each species contains a protein fraction that (i) binds palmitate, (ii) has a molecular mass similar to that of human serum albumin, and (iii) is one of the most rapidly migrating proteins when salmonid plasma is subjected to anodal polyacrylamide gel electrophoresis. We conclude therefore, that salmonids have serum albumins that are homologous to the serum albumin of higher vertebrates.     

Elimination of Homologous And Heterologous (Bovine) Serum Albumin from the Blood Circulation in the Dog)

The elimination of intravenously administered I131-labelled bovine serum albumin has been compared to the elimination rate of relabelled homologous serum albumin in normal and bled dogs, which had lost considerable blood volumes. The investigation shows that during the first four to five days after the administration the elimination is similar of heterologous and homologous serum albumin. This proves that bovine serum albumin can be regarded to be an equivalent plasma expander to homologous serum albumin in the dog. Elimination of homologous as well as heterologous serum albumin follows a simple exponential curve during four to five days after administration. The intravascular half-lives for homologous serum albumin were 6.4 ±1.5 days and 6.4 ± 0.6 days respectively in control and bled dogs. Corresponding values for heterologous (bovine) serum albumin were 5.0 ± 0.3 and 4.8 ± 0.4 days respectively. The quote for cencentrations of homologous and heterologous serum albumin in different tissues was found to be relatively constant approximately 1.4. An exception was the stomach wall in bled dogs which had a quote of 1.1 only.     

Purification and characterization of the serum ferroxidase inhibitor

The inhibitor of the serum ferroxidases, recently detected in rabbit serum, has been purified to homogeneity from human serum by a combination of gel-filtration and ion-exchange chromatography. The molecular weight, chromatographic behavior, electrophoretic mobility, electrofocusing pH, carbohydrate content, and reactivity with anti-human albumin during immunodiffusion indicate that the ferroxidase inhibitor is serum albumin. Copper-binding studies, proteolytic fragmentation studies, and a comparison of the inhibitory potencies of several albumin species which differ in their affinity for copper strongly indicate that albumin elicits its inhibitory effect on the serum ferroxidases by interacting with the functional copper of these enzymes. Kinetic analyses further suggest that albumin competes with substrate (ferrous iron) for binding to the functional copper of the serum ferroxidases.     

Purification and properties of buffalo serum albumin

Based on a detailed study of the solubility of serum albumin, a procedure for its purification by selective ammonium sulphate precipitation has been developed. Using buffalo serum, first extraneous proteins were precipitated by making the serum 2.26 M saturated with ammonium sulphate at pH 7.0 and then albumin was precipitated from the supernatant at 1.9 M ammonium sulphate concentration at pH 4.2. The overall yield of serum albumin thus isolated was about 55% with a purity of 97%. The protein preparation gave a single nearly symmetrical peak on Sephadex G-100 column and virtually a single band on polyacrylamide gel electrophoresis in the presence and absence of SDS. Buffalo serum albumin has a molecular weight of 69,000 Da. The hydrodynamic properties such as Stoke's radius (3.70 nm), diffusion coefficient (6.03 X 10(-7) cm2/s) and frictional ratio (1.36) obtained by analytical gel chromatography, bilirubin binding characteristics and its interaction with anti-bovine serum albumin antiserum suggest that buffalo serum albumin is very similar to BSA in its molecular properties.     

An Analysis of the Heterogeneity of Albumin

A simple and rapid procedure for characterization of serum albumin samples and for the isolation of fractions from fresh serum or commercial sources has been developed, based on DEAE Sepharose CL-6B ion exchange chromatography. Characterization of the fractions included sulfhydryl analysis, gel electrophoresis, and immunoelectrophoresis. Both analytical and preparative procedures were used. It has been shown that the relative content of the fractions varies from individual to individual. It has also been shown that certain fractions found in commercial preparations are artifacts which should be removed before performing serious studies with serum albumin.     

重组人血白蛋白临床研究进展

人血白蛋白是人血浆中最丰富的蛋白质,具有许多重要的生理特性,用途广泛。目前主要以毕赤酵母作为宿主表达的重组人血白蛋白,开发了重组人血白蛋白的纯化技术,同时对重组人血白蛋白结构进行了分析,结果表明与人血浆白蛋白基本一致。临床研究结果表明重组人血白蛋白与人血浆白蛋白有着几乎相同的疗效和安全性。综述了重组人血白蛋白的性质结构分析及酵母表达系统;重点介绍了重组人血白蛋白在临床方面研究进展。     

Effect of Bovine Serum Albumin Incubation on Lettuce Chloroplasts Digested by Trypsin

1. Bovine serum albumin stimulates the DCIP photoreduction activity of lettuce chloroplasts which has been treated with trypsin. When these chloroplast preparations were washed by tricine buffer such "reversible action" can still be obtained. It is possible that bovine serum albumin may be incorporated into trypsin destroyed site of the membrane. 2. Trypsin-induced CCCP inhibitory effect on DCIP photoreduction activity is reversed by bovine serum albumin. 3. Bovine serum albumin partially reverses the trypsin-induced unstacking of lettuce chloroplast membranes. 4. After trypsin digestion, there are absorbance decreases around 500–640 nm. Bovine serum albumin has no effect on these absorbance decreases. It is concluded that the membrane-bound proteins responsible for different functions of chloroplast are heterogeneous. The results also show that there are gate and channel near the position of PSⅡ on chloroplast membrane.     

Comparison of kinetic study of the photochemical changes of (ZZ)-bilirubin IX alpha bound to human serum albumin with that bound to rat serum albumin.

It has been stated by McDonagh, Palma & Lightner [(1982) J. Am. Chem. Soc. 104, 6867-6871] that complexing of bilirubin with serum albumin has a marked species-dependent influence on bilirubin photoisomerization in vitro and in vivo. Therefore the kinetics for the quantitatively important reaction: (Formula: see text) of the photochemical interconversion between bilirubin and its photoisomers bound to human or rat serum albumin in aqueous solution, assayed by h.p.l.c., was used to elucidate the observed species-dependent difference. The relative rate constants for bilirubin bound to human serum albumin, except for k4, the rate of interconversion from (ZZ)-bilirubin into (EZ)-bilirubin, proved to be considerably larger than those for bilirubin bound to rat serum albumin. In accordance with these rate constants, the formation of photoisomers of bilirubin bound to human serum albumin, except for (EZ)-bilirubin, is very rapid and much greater than that for bilirubin bound to rat serum albumin.     

Association of an albumin antigen with phosphatidylcholine liposomes alters the nature of immunoglobulins produced during the immune response against the antigen

Human serum albumin has been injected intravenously in rabbits either free in solution or associated with liposomes. Blood samples were obtained from the rabbits at various time intervals after injection, and two different antibody determinations were performed in each sample. Whereas a haemagglutination technique was applied for determination of predominantly IgM anti-human serum albumin antibodies, a second technique, using antigen-coated Sepharose beads and horseradish peroxidase-conjugated anti-rabbit IgG, was used to detect the IgG anti-human serum albumin antibodies. Liposomes appeared to enhance strongly the IgM response against human serum albumin. No such marked differences were found, however, between the IgG responses against liposome-associated or free human serum albumin. The conclusion is drawn that the immunoadjuvant effect of liposomes during the primary immune response against an albumin antigen is mainly due to an enhanced IgM antibody production.     

Identification of a "new" rabbit and human serum protein with fast electrophoretic mobility

A new protein has been identified in both rabbit and human serum. The salient characteristic of this protein is its high negative charge as revealed by its rapid anodal migration during electrophoresis at alkaline pH. This protein has tentatively been designated fast-moving protein because of its electrophoretic mobility. Molecular weight determination by polyacrylamide gel electrophoresis in sodium dodecyl sulfate indicated that the molecular weight was 85,000 daltons. A goat antiserum made to the rabbit fast-moving protein cross-reacted with both rabbit and human serum albumin. Although no apparent structural relationship between fast-moving protein and albumin was found by peptide-mapping studies, a peptide with a molecular weight of 24,000 daltons and with antigenic determinants in common with rabbit fast-moving protein, was isolated from cyanogen bromide-treated human serum albumin. The structural relationship between fast-moving protein and albumin is discussed.     

Idiotypy of antibodies against human serum albumin in immunized rabbit serum, which are directed against different regions of this antigen

Idiotypy has been studied in rabbit antibodies against human serum albumin. Antibodies which are directed against three different regions of serum albumin have similar idiotypic specificities. The molecular distribution of idiotypic determinants may be different in antibodies with specificity for different determinants as revealed for example by their precipitability or non precipitability by the same anti-idiotypic antibodies. The anti-albumin antibodies which are not precipitable by the anti-idiotypic antibodies, though they do combine with them, become precipitable after being mildly polymerized. Similar idiotypic specificities may be found in antibodies to serum albumin and in immunoglobulins apparently devoid of anti-serum albumin antibody function.     

Raman studies of bovine serum albumin.

The Raman Spectra of bovine serum albumin have been obtained in the solute state, in alkaline and acidic solutions, and in the gel. The reversible denaturations of bovine serum albumin solutions by heat, acid's, and alkali were studied and a new mechanism for heat denaturation has been proposed based on a continuous unfolding of the α-helices.     

o-Quinones formed in plant extracts. Their reaction with bovine serum albumin

1. The reactions between chlorogenoquinone, the o-quinone formed during the oxidation of chlorogenic acid, and bovine serum albumin depend on the ratio of reactants. 2. When the serum albumin is in excess, oxygen is not absorbed and the products are colourless. This reaction probably involves the thiol group of bovine serum albumin; it does not occur with bovine serum albumin which has been treated with p-chloromercuribenzoate, iodoacetamide or Ellman's reagent. 3. When bovine serum albumin reacts with excess of chlorogenoquinone, oxygen is absorbed and the products are red. The red colour is probably formed by reaction of the lysine in-amino groups of bovine serum albumin, as it is prevented by treating the protein with formaldehyde, succinic anhydride or O-methylisourea. 4. Bovine serum albumin modified by a 1.5-fold (BSA-Q) and a fivefold (BSA-Q2) excess of chlorogenoquinone were separated by chromatography on DEAE-Sephadex A-50, and some of their properties observed. 5. Reaction of BSA-Q2 with fluorodinitrobenzene suggests that the terminal alpha-amino group, as well as lysine in-amino groups, are combined with chlorogenoquinone.