Hydrolysis of Gangliosides in Micellar and Liposomal Dispersion by Bacterial Neuraminidases
In aqueous media gangliosides form aggregates whose micellar weights are about 250,000 daltons (GAMMACK, 1963; YOHE, ROARK and ROSENBERG, 1976). In these micelles the hydrophylic portion, which contains the carbohydrate and neuraminyl residues is directed to the bulk water-phase and thereby interacts with the soluble bacterial neuraminidases. This paper presents a brief discussion of studies, done in our laboratory on the hydrolysis of mono-, di- and trisialogangliosides by the neuraminidases of Cl. perfringens and V. cholerae. These studies suggested that in micellar dispersion the gangliosides are poor substrates for these enzymes. Enzymatic reaction rates increased considerably when the gangliosides were mixed with a lipid or detergent. The effect of adding a bile salt was absolute in the case of GM1 which was not hydrolyzed at all unless a bile salt was added (see also references of WENGER and WARDELL, 1972, 1973), but was also observed using GM3, which is hydrolyzed by these neuraminidases (WIEGANDT, 1966; BURTON, 1963). The effect of an additive was very striking when di- and trisialogangliosides were used. These compounds are hydrolyzed by both bacterial neuraminidases, yielding GMl as the end product (WIEGANDT, 1966; BURTON 1963). Rates of hydrolysis increased somewhat when certain lipids were added to a dispersion of mixed brain ganglio-sides (LIPOVAC, BIGALLI and ROSENBERG, 1971).
KeywordsBile Salt Mixed Micelle Critical Micellar Concentration Clostridium Perfringens Sodium Taurocholate
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- LIPOVAC V., BIGALLI G. and ROSENBERG A. (1971): Enzymatic action of sialidase of Vibrio cholerae on brain gangliosides above and below the critical micelle concentration. J. biol. Chem. 246, 7642–7648.Google Scholar