Serum Glycoconjugates

Removal of the penultimate sugar, mostly galactose, leads to a normalization of both the survival time in the circulation and the distribution among organs. On the first sight the extraordinary behaviour of asialo-transferrin did not fit in this general scheme, because desialylation apparently did not reduce the half-life. More detailed studies finally revealed that small amounts of asialo-transferrin are 

During receptor-mediated endocytosis (for rev. see Goldstein et al. 1979) the ligand remains associated with the transport vehicle within the cell the complex dissociates and the ligand is finally degraded (Bridges et al. 1982). The constant of internalization is 3.1 x 10 - sec., while the dissociation constant has a value of 

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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... 

Figure 2. Immunochemical studies ofthe specificity ofrabbit antibodies elicited against Parp(al—3)D-Manp-BSA glycoconjugates (02). Top structures of the Salmonella O-antigen-specific saccharides used. Center Inhibition of precipitation in mixtures of anti-PM-BSA serum andS. paratyphi A PS. Key Center V, Octasaccharide S. paratyphi A. var. Durazzo ft.. Dodecasaccharide S. paratyphi A. var. Durazzo (II) , Parp D-Manp 4 OMe a., Parp -jpi- D-Manp O-0-NHCSNH(CH2)5COOH (VIII) m. Parp -j-i- D-Manp O-0-NHCOCF. (VII) U, Parp OMe A, Dodecasaccharide...

Anti-a-D-mannose antibodies have been isolated from the serum of rabbits immunized with the glycoconjugate of a-D-mannose and bovine serum albumin [85], The antibodies were purified by affinity chromatography with adsorption on a mannosyl-Sepharose column and elution with a-D-mannose or methyl a-D-mannoside. Such antibodies should be especially useful for studying the detection of diseases due to the appearance of abnormal glycoproteins that contain mannose polymers. 

Mackiewicz, A. and Mackiewicz, K. (1995) Glycoforms of serum ai -acid glycoprotein as markers of inflammation and cancer. Glycoconjugate Journal 12,241-247. 

Alcohol interferes with a number of glycoconjugation reactions, perhaps as the result of acetaldehyde inhibition of hepatic glycotransferases. The isoforms of transferrin have been studied as markers of alcohol consumption, as excessive ethanol consumption results in the appearance in serum... 

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