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Inhibition of the UDP‐ N ‐Acetylgalactosamine: GM 3 , N ‐Acetylgalactosaminyl Transferase by Gangliosides
Author(s) -
Nores G. A.,
Caputto R.
Publication year - 1984
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1984.tb02773.x
Subject(s) - phosphatidic acid , phosphatidylethanolamine , chemistry , incubation , ganglioside , sphingomyelin , transferase , biochemistry , membrane , substrate (aquarium) , phosphatidylcholine , chromatography , enzyme , inhibitory postsynaptic potential , pi , phospholipid , biology , endocrinology , ecology
Gangliosides in the range of 0.1–0.4 m M inhibited the UDP‐ N ‐acetylgalactosamine:GM 3 , N ‐acetyl‐galactosaminyl transferase (EC 2.4.1.79) of chicken retina. Other lipids such as phosphatidylethanolamine, sphingomyelin, sulfatides, and phosphatidic acid in concentrations similar to those of gangliosides did not affect the enzyme activity significantly. GM 3 has an inhibition capability slightly less than that of gangliosides with two or three sialyl groups in their molecules, while asialo‐GM 1 is clearly less inhibitory. The inhibitory effect of a constant amount of GT 1 ganglioside was higher at low concentrations of membrane preparation, but the inhibition was similar at different concentrations of the substrates GM 3 or UDP‐ N ‐acetylgalactosamine and at all incubation times studied. The added gangliosides were found attached to the membranes. In this attached state they may act either as substrate or inhibitor. The inhibitory effect of gangliosides was not apparent when a mixture of Triton CF 54‐Tween 80 was added to the incubation medium at concentrations >0.33%.