Brain sialidase

Ohman and coworkers192 made a detailed study of human-brain sialidase, and found that this enzyme occurred mainly in a particulate... 

Ca + has no effect on the enzymes from the mammary gland (Tulsiani and Carubelli, 1971), brain (sialidase A) (Venerando et al., 1975), or liver (Miyagi and Tsuiki, 1985). Brain sialidase B, however, is slightly activated by the cation (Venerando et al., 1975). Cu " at 1 mM strongly inhibits the activity of most mammalian enzymes (Tulsiani and Carubelli, 1971 Miyagi and Tsuiki, 1985). 

Heijlman, J., and Roukema, P. A., 1972, The action of calf brain sialidase on gangliosides, sialoglycoproteins and sialoglycopeptides, J. Neurochem. 19 2567-2575. 

Ohmann, R., Rosenberg, A., and Svennerholm, L., 1970, Human brain sialidase. Biochemistry 9 3774-3782. 

Schengrund, C.-L., and Rosenberg, A., 1970, Intracellular location and properties of bovine brain sialidase, J. Biol. Chem. 245 6196-6200. 

C. Oehler, J. Kopitz, and M. Cantz, Substrate specificity and inhibitor studies of a membrane-bound ganglioside sialidase isolated from human brain tissue, J. Biol. Chem., 383 (2002) 1735-1742. 

Sialidase activities in light and heavy lysosomal fractions have been characterized in rat mammary gland (Tulsiani and Carubelli, 1971), human liver (Meyer et al., 1981), and mouse brain (Fiorilli et al., 1991). The heavy lysosomal fraction shows higher specific enzyme activity than the light fraction, but there is no difference in pH optimum, value, or substrate specificity between the two fractions. In mouse brain, the sialidase activities in the heavy and light lysosomal fractions exhibit different developmental profiles, suggesting that the expression of these activities may be regulated independently (Fiorilli et al.y 1991). 

The membrane-bound lysosomal enzyme in rat brain has been solubilized from the particulate fraction and partially purified (Miyagi et aL, 1990a). The sialidase activity can be separated into two peaks, corresponding to sialidases I and II, by AH-Sepharose column chromatography. Using specific antibodies against the enzymes, it has been shown that sialidase I is localized in synaptosomal membranes, and sialidase II in both synaptosomal and lysosomal membranes. The latter species has been further purified by 2150-fold with a recovery of 0.7%. 

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