In vivo incorporation of palmitic acid and galactose in glycolipids of Trypanosoma cruzi epimastigotes.

Incubation of epimastigote forms of Trypanosoma cruzi with (3H)-palmitic acid and (3H)-galactose, respectively, results in the incorporation of both precursors into the lipopeptidophosphoglycan (LPPG) and in at least two glycosphingolipids. Palmitic acid was incorporated into sphinganine and sphingenine, identified after hydrolysis, respectively, of the major and the minor glycosphingolipid. The purified glycosphingolipids labeled with either precursor migrated with a Rf similar to that of a sample labeled by periodate oxidation and borotritide reduction in which sialic acids have been previously characterized. This, together with the fact that the palmitic acid labeled glycosphingolipids were partially hydrolysed with neuraminidase favors a ganglioside-like structure for these compounds.

Sialoglycolipids in Trypanosoma cruzi.

Mild oxidation of epimastigote forms of T.cruzi followed by sodium borotritide reduction incorporates radioactivity into glycolipid fractions. Column chromatography on silica gel of the chloroform:methanol (2:1) extract separated two main peaks of radioactivity. Treatment with neuraminidase released 30% and 18% of the radioactivity, respectively. Paper chromatography showed peaks of radioactivity with relative migration to NANA7 of 1.33 in fraction A and 1.33 and 1.51 in fraction B. When unlabeled cells were submitted to a Folch extraction, thin layer chromatography of the upper phase showed at least two components detected with the resorcinol-copper reagent. Enzymatic and mild acid hydrolysis released a sialic acid with a migration relative to NANA of 1.22. These results suggest that a substituted sialic acid is present in glycolipids of the epimastigote form of T.cruzi.