Direct sialic acid transfer from a protein donor to glycolipids of trypomastigote forms of Trypanosoma cruzi
Labeled sialoglycolipids were purified from tissue culture-derived trypomastigotes incubated with [3H]fetuin. Thin layer chromatography of [3H]sialoglycolipids showed three components with the same migration as gangliosides extracted from parasites incubated with [3H]palmitic acid. Neuraminidase tre...
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| Autores principales: | , , , |
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| Formato: | JOUR |
| Materias: | |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_01666851_v26_n1-2_p135_Zingales |
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| Sumario: | Labeled sialoglycolipids were purified from tissue culture-derived trypomastigotes incubated with [3H]fetuin. Thin layer chromatography of [3H]sialoglycolipids showed three components with the same migration as gangliosides extracted from parasites incubated with [3H]palmitic acid. Neuraminidase treatment or mild acid hydrolysis confirmed the presence of [3H]sialyl residues in sialoglycolipids synthesized after [3H]fetuin incubation. Labeling was not observed when parasites were incubated with free [3H]sialic acid (C7 derivative), suggesting that sialyl residues are directly transferred in vivo to gangliosides, by an enzymatic reaction possibly catalysed by a sialyl transferase (transglycosylase). Sonicated extracts of trypomastigotes incubated with [3H]fetuin catalysed the labeling of endogenous glycoconjugates as well as of bovine brain gangliosides. The transglycosylase activity was found associated with the particulate fraction and could be solubilized with Triton X-100. The specific activity of the sialic acid transglycosylase in epimastigotes is 17% of that found in trypomastigotes. Addition of an excess free sialic acid did not inhibit the reaction, suggesting that transfer does not occur via a pool of free sialic acid. © 1987. |
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