Albumin Molecular Weight Research Articles

The use of polyelectrolytes as osmotic agents for peritoneal dialysis

Various small and large molecules have been studied as osmotic agents to replace dextrose in peritoneal dialysis. Macromolecules are attractive because of their slow absorption from intraperitoneal solutions; however, it has been assumed that they are only marginally effective as osmotic agents unless they function as polyelectrolytes at physiological pH. In experimental exchanges conducted in rats we measured volume changes induced by Gelifundol (5.5% oxypolygelatin) and Ringers lactate to which was added either nothing, 4.25% dextrose, or 5% albumin. In the control exchanges using Ringers lactate, intraperitoneal fluid volume remained unchanged for eight hours. The volume changes induced by 4.25% dextrose were complete within two hours and resulted in a two-thirds increase over the amount of fluid administered. In both series in which polyelectrolytes were used volume transport was sustained throughout an eight hour dwell. With 5% albumin the total increase in fluid volume was about 40% of that installed, while Gelifundol caused fluid volume to double. Qualitatively similar results were obtained in transport studies conducted in vitro. Physical studies of the oxypolygelatin solutions indicated that the fixed charges per liter were comparable to those in the albumin solutions. Thus the different volume transport the two proteins induced could not be attributed to Donnan effects. However, since the molecular weight of albumin is triple that of Gelifundol the van't Hoff pressures of the two macromolecules can explain the observed differences in volume transport. These results suggest that neutral macromolecules deserve further study as potential osmotic agents for peritoneal dialysis.

Use of electrophoretic techniques in determining the composition of seed storage proteins in alfalfa

Holoprotein molecular weights and polypeptide composition can be determined for complex mixtures of oligomeric proteins using two-dimensional electrophoretic techniques. The variety of two-dimensional analyses presented here is a reflection of the general usefulness of each method for the identification and characterization of the different classes of seed storage proteins in alfalfa. These techniques can be applied to studies of storage proteins in other seeds as well as non-seed storage proteins. The major seed storage proteins in alfalfa are medicagin (a legumin-like globulin), alfin (a vicilin-like globulin) and a family of lower molecular weight albumins (LMW1-3). These comprise 30%, 10%, and 20%, respectively, of the total extractable protein from cotyledons of mature seeds. Alfin is a heterogeneous oligomeric protein (Mr approximately 150,000) composed of polypeptides ranging in size from Mr 14,000 to 50,000 (alpha 1-alpha 6; 50,000, 38,000, 32,000, 20,000, 16,000 and 14,000, respectively). Medicagin is also a high molecular weight oligomeric protein, but requires high concentrations of salt for solubilisation. It is comprised of a family of individually distinct subunits, each composed of an acidic polypeptide (A1-A9; Mr 49,000 to 39,000) linked via disulphide bond(s) to a basic polypeptide (B1, B2, B3; Mr 24,000, 23,000 and 20,000, respectively). This pairing is highly specific and two families are recognizable on the basis of the B polypeptide (B3 or B1/B2). Subunits (Mr approximately 50,000-65,000) are assembled as trimers (8S) or larger oligomers (12S-15S) in mature seeds. The lower molecular weight albumins (LMW1-3) are acidic (pI less than 6), and consist of sets of disulphide-bonded polypeptides (Mr 15,000 and 11,000).

Characterisation by two-dimensional gel electrophoresis of the protein components of protein bodies, isolated from the developing endosperm of wheat ( Triticum aestivum)

Protein bodies were extracted from the developing endosperm of two varieties of wheat and isolated by sucrose-gradient centrifugation. Their protein constituents were characterised by two-dimensional electrophoresis and compared with the proteins of the mature endosperm. It was concluded that for both varieties all the major proteins previously identified as prolamins, i.e. glutenin subunits and gliadins, occur in protein bodies. Also present in protein-body preparations are the ‘triplet-band’ proteins. In contrast, the ‘non-storage proteins’ occur in only trace amounts in protein-body preparations while the high molecular weight (HMW) albumins are absent. Also absent are the 7S storage globulins, which is probably due to their location in the embryo and aleurone layer rather than the starchy endosperm.

Synthesis of mRNAs coding for abundant endosperm proteins during wheat grain development

The expression of mRNAs encoding major endosperm proteins has been investigated during wheat grain development. The synthesis and accumulation of the most abundant endosperm proteins, the prolamins gliadin and glutenin, high molecular weight (HMW) albumins and non-storage proteins were examined by comparing 2-dimensional separations of in vivo and in vitro synthesized proteins. Major changes occur during early stages of grain development. No prolamin mRNA or proteins were observed at 5 days after flowering (5 DAF), but both can be detected at 10 DAF. The amounts of prolamin mRNAs increase sharply until the mid developmental phase and then decline, but prolamin proteins continue to accumulate until grain maturity. The mRNA level of different prolamin classes during development was measured using various cDNA clones. Although controlled by genetic loci on different chromosomes, the HMW albumins and the so-called non-storage proteins are also synthesized in a very similar fashion to the prolamins. A common transcriptional control mechanism is therefore likely which coordinates mRNA synthesis at different genetic loci. Differences in levels of proteins accumulated were found however by comparing in vivo and in vitro synthesized gliadins and non-storage proteins suggesting an additional level of control of protein synthesis during grain development.

The distribution of serum albumin in the rat testis, studied by electron microscope immunocytochemistry on ultrathin frozen sections.

The distribution of serum albumin is of interest in the rat testis because this protein is the principal carrier for testosterone in the plasma and interstitial fluid of this species. We have localized extravascular serum albumin in the rat testis at the electron microscope level, using gold particle immunocytochemistry on ultrathin frozen sections of tissue fixed lightly by perfusion. The same localization was obtained with three different antisera. Preabsorption and normal rabbit serum controls were negative, and Western blots of testis extracts showed major activity only at the molecular weight of albumin. Serum albumin occurred in substantial concentration throughout extracellular space in the interstitial tissue, as well as in the space between the boundary layer and the base of the seminiferous epithelium. Immunoreactivity extended between Sertoli cells, as well as around spermatogonia and early primary spermatocytes (to stage 11), but did not traverse the Sertoli-Sertoli junctions that comprise the blood-testis barrier. Macrophages in the interstitial tissue showed some endocytic activity. If perfusion fixation was carried out in a manner that flushed most of the albumin from the interstitial space, then a layer of albumin remained on the surface of Leydig cells and many macrophages but was minimal or absent on the surface of other cell types that are normally in contact with albumin, such as Sertoli cells, spermatogonia, myoid cells, lymphatic endothelium, fibroblasts, or cells of blood vessels.

Occurrence of Low Molecular Weight and High Cysteine Containing Albumin Storage Proteins in Oilseeds of Diverse Species

Occurrence of Low Molecular Weight and High Cysteine Containing Albumin Storage Proteins in Oilseeds of Diverse Species

Evidence That the Castor Bean Allergens Are the Albumin Storage Proteins in the Protein Bodies of Castor Bean

The well characterized castor bean (Ricinus communis L.) allergens were identified as the low molecular weight albumin storage proteins in the matrix of the protein bodies in the endosperm. The methods of identification involved molecular weight estimation, amino acid composition, stability at 100 degrees C, solubility in various solvents, gel electrophoresis, and immunological techniques. The finding explains the wide distribution of allergens in various seeds.

Airway mucosal permeability in the Ascaris suum-sensitive rhesus monkey

The permeability of the airways to technetium 99m-labeled albumin was measured in Ascaris suum-sensitive rhesus monkeys. All 8 animals were skin-sensitive to Ascaris suum (AA) antigen, 4 being respiratory responders (R) and 4 nonresponders (NR) to aerosolized antigen. In the absence of antigen challenge there were no differences in the accumulation in the blood of radioactive material from the tracheobronchial tree between the R and NR animals. After a five-minute challenge with aerosolized AA, there was a threefold increase in the rate of accumulation of radioactive material in the blood over control for the R group with no effect noted in the NR group. Gel filtration data indicated that the radioactivity in the blood most likely represented low molecular weight albumin fragments, resulting from spontaneous degradation of Tc-albumin, that crossed the mucosa and partially bound to circulating albumin. It is concluded that hyperpermeability of the airway mucosa probably is not a factor that contributes to the selective responsiveness of the R group to aerosolized antigen, and that airway permeability is increased consequent to the allergic reaction mediating acute bronchoconstriction.

Studies on urinary low molecular albumin

Low molecular proteins contained in the urine of the patients of multiple myeloma and diabetes mellitus were studied physicochemically and immunologically. Urinary low molecular proteins, approximately 10, 000 to 50, 000 in molecular weight, were concentrated about 100 times by ultrafiltration.Immunoelectrophoresis of these low molecular proteins revealed fractions common in antigenic properties with albumin, α1-antitrypsin, ceruloplasmin, transferrin, IgG and Bence-Jones protein. The low molecular weight albumin was separated and purified by chromatography on Sephadex G-75 and DEAE-cellulose. Purity of this albumin was checked by double immunodiffusion and polyacrylamide gel disc electrophoresis. The approximate molecular weight of this albumin was measured as 10, 000 by ultracentrifugal and light scattering analysis. The ability of the low molecular fraction to induce formation of antibody was confirmed with experimental inoculation to rabbits.

The structure of a calcium-binding protein from carp muscle.

We have determined the structure of one of the low molecular weight albumins of carp, using standard techniques of amino acid sequence analysis and heavy atom replacement crystallography. Originally we became interested in these so-called myogens or parvalbumins because of their unusual amino acid compositions—10% Phe and 20% Ala with little or no Trp, Tyr, Met, His, Cys or Arg (Konosu, Hamoir and Pechere, 1965). Subsequently it has been found that they have a high calcium-binding affinity (Pechere et al., 1971). These two characteristics suggest that the myogen to be described is analogous to troponin-A of mammalian and avian muscle (Ebashi et al., 1969; Greaser and Gergely, 1970; Drabikowski et al., 1971). Troponin-A mediates the effect of calcium released from the sarcoplasmic reticulum by the nervous impulse by reversing the inhibition of actomyosin contraction imposed by tropomyosin.

Crystal data for low molecular weight albumins of carp

We have grown crystals of the low molecular weight albumins of carp suitable for a 2.0-Å resolution structure determination. Component 3 forms monoclinic crystals; space group C2 with a = 28.2 A ̊ , b = 61.0 A ̊ , c = 54.3 A ̊ and β = 95 °10′.

Tryptic peptide maps and terminal amino acid residues of low molecular weight proteins from the white muscles of Cyprinus carpio, Gadus callarias and Tilapia macrochir boul

1. 1. The tryptic peptide maps of seven low molecular weight albumins purified from the white muscles of Cyprinus carpio (carp), Gadus callarias (cod) and Tilapia macrochir Boulenger are dealt with in detail. 2. 2. The results provide additional support to our previously proposed homology of these fish albumins. 3. 3. Our extended investigations to find out the terminal amino acid residues revealed that N-terminal amino acid is acetylated; carboxypeptidase A, B as well as hydrazinolysis have not liberated any free C-terminal residue in these proteins.

Macromolecular degradation products of bovine plasma albumin

With the aid of a recording interferometer, gradient elution chromatograms from diethylaminoethylcellulose were obtained for chymotrypsin, for bovine plasma albumin, and for dialyzed chymotrypsin- and hydrochloric acid-hydrolyzates of bovine plasma albumin. In the case of the hydrolyzates by chymotrypsin, fractions collected at 1.2-ml. intervals were subjected to molecular-weight determinations with the Archibald technique. The hydrolyzates were also examined electrophoretically. From the combined data of the chromatographic recorder and the ultracentrifuge it was possible to construct molecular-weight-distribution curves for the dialyzed hydrolyzates. Hydrolysis of bovine plasma albumin by chymotrypsin for 24 hr. at 37 °C. was found to lead to macromolecular products containing about 10% of a peptide material of molecular weight 19,000, and small amounts of materials with molecular weights higher than that of albumin, in addition to a preponderant amount of material having the molecular weight of albumin. Electrophoresis of this hydrolyzate also demonstrated the presence of two major components.