Glycoproteins serum

The isolation and chemical compositions of a, -acid glycoproteins from the plasma of humans, rabbits, pigs, rats, and chickens have been reported. The a,-acid glycoproteins from the plasmas of chickens, humans, and rabbits contain almost identical amounts of carbohydrate, whereas those from porcine and murine plasmas contain less carbohydrate. The concentrations of orosomucoid, a,-anti- 

The heterogeneity of each of the five carbohydrate components of human-serum a j-glycoprotein has been examined. A function of this glycoprotein might be to inhibit certain lymphocyte responses, including blast transformation induced by mitogens and allogeneic cells.  

Chemical modification e.g. periodate oxidation and then reduction) or loss of the terminal N-acetylneuraminic acid residues of human-plasma a,-antitrypsin did not destroy its ability to inhibit either trypsin or chymotrypsin neither did oxidation of the exposed D-galactopyranosyl residues in the desialylated glycoprotein with D-galactose oxidase. However, enzymic oxidation of the D-galactopyranosyl residues increased the survival time of the modified glycoprotein in plasma towards that exhibited by fully sialylated a -antitrypsin, whereas the desialylated glycoprotein was rapidly cleared following injection into rats. Contrary to previous evidence, there appears to be little or no difference between the carbohydrate compositions of the M and Z variants of human-plasma a,-antitrypsin.  

A leucine-rich aj-glycoprotein (mol. wt. 4.96 x 10 ) in human serum (2.1 mg per 100 ml of serum) appears to consist of a single polypeptide chain and 23% of carbohydrate. Human-plasma otj-SH glycoprotein has been freed from zinc aj-glycoprotein—which possesses a similar molecular weight and a similar isoelectric point—by affinity chromatography on a gel-bound zinc chelate.  

The extents of sialylation of eleven plasma hydrolases have been examined. Most plasma hydrolases e.g. a-L-fucosidase and a-D-mannosidase) were eluted from DEAE-cellulose at a lower salt concentration after treatment with neuraminidase, although the elution profiles of p-D-glucosidase, P-D-xylosidase, and acid phosphatases were unaffected, indicating that they are less susceptible to the action of neuraminidase. The structure (9) assigned (G. Spick, B. Bayard, B. Fournet, and G. Strecker, F.E.B.S. Letters, 1975, 50, 296) to the carbohydrate component of human serotransferrin has been confirmed by high-resolution H n.m.r. spectroscopy. Electrophoresis separated human serotransferrin into four molecular forms that contain different proportions of bound iron. The nature of the interaction of renins from human and rabbit kidneys with immobilized concanavalin A, and their subsequent desorption with methyl a-D-mannopyrano-side, suggested that both proteins are glycosylated.  

The role of sialic acid residues in determining the life-time of circulating cells and glycoproteins and the importance of desialylation have been discussed, Chromatography on Blue Dextran 2000 coupled to agarose has been used in the rapid separation of factor X from citrated human plasma a 2(XX)-fold purification was achieved, Inhibition by the antithrombin-heparin cofactor of the conversion of factor IX into its active form by factor IXa has been examined. The process is time-dependent and requires a 1 1 combination 

Yamashita, Y. Tachibana, and A. Kobata, Arch. Biochem. Biophys., 1976, 174, 582. 

Newman, R. Harrison, and G. Uhlenbruck, Biochim. Biophys. Acta, 1976, 433, 344. 

Nichols, A. Bezkorovainy, and R. Paque, Biochim. Biophys. Acta, 1975, 412, 99. 

A number of highly purified, neuraminidase-treated human serum glycoproteins, have been examined for their cross-reactivity with several lectins having anti-D-galactosyl specificity, in an attempt to characterize these glycoproteins with respect to their slightly differing carbohydrate moieties.  

Evidence has been presented for the existence of a hepatic receptor that specifically binds oligosaccharides containing 2-acetamido-2-deoxy-3-G-a-L-fucopyranosyl-D-glucopyranosyl groups. Deglycosylation or periodate oxidation of these glycoproteins enhances the circulation time. 

Receptors to asialoglycoproteins have been isolated from rabbit liver by affinity chromatography on immobilized D-galactosyl- and o-glucosyl-derivatives of bovine serum albumin.  

Affinity chromatography on immobilized Ricinus communis agglutinin has been used for the isolation of a heterogeneous population of human serum inhibitors of the binding of desialylated glycoproteins to rat hepatocyte membranes. The inhibitors are themselves desialylized glycoproteins, which are present in small amounts in normal human serum but in increased levels in serum from patients with cirrhosis. 

The clearance from plasma of lysosomal enzymes and glycoproteins terminating in 2-acetamido-2-deoxy-D-glucosyl or D-mannosyl groups has been studied in non-parenchymal cells of the liver.  

A hepatic receptor, which recognizes and binds specifically to serum glycoproteins bearing terminal non-reducing 2-acetamido-2-deoxy-D-glucosyl residues, has been isolated from chickoi liver by chromatography on immobilized 

Clearance of ribonuclease B from rat circulation depends on specific recognition of the a-D-mannosyl residues of the attached oligosaccharide and is inhibited by the presence of yeast mannan. The clearance from the circulation occurs primarily in liver, spleen, and bone marrow non-parenchymal cells. Quantitative aspects of the hepatic clearance mechanism for the elimination of asialo-fetuin and asialo-orosomucoid by the rat have been described.  

Functions of Blood Group Protein Antigens of Erythrocytes 

Blood Group (abbreviation) Locus Name Protein 

Colton (Co) AQPl Aquaporin 1 water channel protein 

Blood Group Protein Antigens as Microbial Receptors  

Removal of senescent red blood cells from the circulation has been attributed to desialylation of the membrane glycoproteins. In vitro removal of sialic acid from human red blood cells and introduction of the modified cells into the circulatory system result in drastic shortening of their life span. However, aging and removal of red blood 

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Antitrypsin is a 394 amino acid, 52 kDa serum glycoprotein. It is synthesized in the liver and secreted into the blood, where it is normally present at concentrations of 2-4 g l-1. It constitutes in excess of 90 per cent of the arglobulin fraction of blood. 

L6. Laurell, A.-B., Influence of alpha-streptococci, pneumococci and Pasteurella pseudotuberculosis on human serum glycoproteins. Acta Pathol, et Microbiol. Scand. 47, 429 (1959). 

Madera, M., Mechref, Y, Klouckova, I., and Novotny, M. V., Semiautomated high-sensitivity profiling of human blood serum glycoproteins through lectin preconcentration and multidimensional chromatography/tandem mass spectrometry. Journal of Proteome Research 5(9), 2348-2363, 2006. 

These studies demonstrating a protective effect of sialic acid residues on serum glycoproteins provide an explanation for earlier, conflicting observations about the biological effect of, for example, desialylated erythropoietin, which stimulates erythropoiesis only after direct application to bone-marrow cell-cultures, and not after injection into the blood stream.469 In the latter experiment, only the native, sialylated hormone was active. Rapid clearance and inactivation of follicle-stimulating hormone,470 or interferon,471 after treatment with sialidase may be explained by uptake into liver cells. 

Sialic acid seems to be involved not only in regulation of the lifetime of soluble, serum glycoproteins but also of mammalian blood-cells. It was observed by Woodruff and Gesner474 that desialylated lymphocytes are reversibly trapped in liver they recirculate to the blood stream after about 24 h. This phenomenon was confinned with Listeria-specific, mouse T lymphocytes, which accumulated in the liver for one day, in contrast to the control cells.60 Reappearance of these cells in the circulation after one day may be explained by re-sialylation of their membrane glycoconjugates. This time period is in the range observed for the turnover of sialic acid in cell membranes, lasting, for example, for 33 h in rat-liver hepatocytes.475... 

Various studies have shown the toxicity of various free monosaccharides towards mammalian cells. L-Fucose was found to inhibit the growth of some cells in culture, but only at high doses,292 and to inhibit the growth of implanted, mammary tumors in rats.293 In an examination of the effect of 93 carbohydrates on cell proliferation,294 D-fucose was one of the 42 that were toxic or growth-inhibitory, but the effect of L-fucose was not reported. The inhibitory effect of L-fucose in implanted, mammary tumors293 was considered to be accompanied by its incorporation into serum glycoproteins, and this would offer a possible explanation for some of its biological properties. 

Identification of Serum Glycoproteins by SDS-PAGE and Western Blotting... 

Western blotting has become an important, modern technique for analysis and characterization of proteins. The procedure consists of, first, the electrophoretic transfer (blotting) of proteins from polyacrylamide gels to synthetic membranes. The transferred blots are then probed using immunological detection methods to identify proteins of specific structure and/or function. In this experiment, bovine serum will be fractionated by SDS-PAGE and the proteins blotted onto a nitrocellulose membrane. Serum glycoproteins will be identified by their specific interaction with the lectin concanavalin A. 

In Fig. 4, we show representative results. First, we detected an antibody reactivity specific for the carbohydrate moieties of an abundant human serum glycoprotein asialo-orosomucoid (ASOR) (Fig. 4B). Second, we found that lectin PHA-L (Phaseolus vulgaris L ) is specific for a defined complex carbohy-... 

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