Liver sialidase

Nagai T, Miyaichi Y, Tomimori T, Yamada H. Inhibition of mouse liver sialidase by plant flavonoids. Biochem Biophys Res Commun 1989a 163 25-31. 

Substrates Rat liver Sialidase activity" Rat muscle s Rat kidneys... 

Bemacki, R. J., and Bosmann, H. B., 1973, Rat-liver-sialidase activity utilizing a tritium-labeled sialic acid derivative of glycoprotein substrates, Eur. J. Biochem. 34 425-433. 

Miyagi, T., Goto, T., and Tsuiki, S., 1984, Sialidase of rat hepatomas Quantitative and qualitative comparison with rat liver sialidase, Gann 75 1076-1082. 

It should be noted that sialidase deficiency has been observed386 in the liver of SM/J mice tested with 4-methylumbelliferyl a-Neu5Ac. 

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. 

K. Ikeda, K. Sano, M. Ito, M. Saito, K. Hidari, T. Suzuki, Y. Suzuki, and K. Tanaka, Synthesis of 2-deoxy-2,3-didehydro-jV-acetylneuraminic acid analogues modified at the C-4 and C-9 positions and their behaviour towards sialidase from influenza virus and pig liver membrane, Carbohydr. Res., 330 (2001) 31 11. 

For instance a-fucosides and a-sialosides, which are both difficult to produce by means of classical carbohydrate chemistry, have been synthesized using the corresponding nitrophenyl glycoside donors by applying pig liver a-fucosidase [59] and the sialidase from Vibrio cholerae [60], respectively. 

Acetylation of mucin-bound and membrane-bound sialic acids makes them more resistant towards sialidase action [8,33,245,853,854]. This may be one of the reasons why intestinal mucins, especially of the colon, are often O-acetylated (ref. [245], and section 8.4.2). The high level of 0-acetylation of sialic acids observed in the endothelia of blood vessels, e.g, in liver, detected by histochemical methods using influenza C virus hemagglutinin, is assumed to have a similar function [234,235,730]. 

Glycoprotein sialidase (neuraminidase) (EC 3.2.1.18). Other lysosomal activities in liver sometimes increased. Sialyloligosaccharides accumulate. Mental retardation, skeletal abnormalities and Hurler-type facial features may be present in varying degrees, or absent. Hepatosplenomegaly, renal involvement and hydrops fetalis sometimes present. 

Sialidase-treated erythrocytes from rats, unlike the normal erythrocytes, preferentially adhered to mononuclear spleen cells and Kupffer cells of the liver. This recognition manifests itself, both in autologous and homologous systems, by the adhesion of complementary cells in the form of rosettes. This process may be the normal physiological mechanism for removing circulating erythrocytes that have a decreasing proportion of sialic acid residues. 

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