A method has been developed to identify the repeating phosphosaccharide units of Leishmania lipophosphoglycans using electrospray mass-spectrometry (ES-MS). Cone voltage-induced fragmentation of intact lipophosphoglycan was found to be as effective as analysis of mild acid hydrolysates in identifying the degree of modification of the repeating units of lipophosphoglycans derived from Leishmnnia mexicana and Leishmania,major. This finding was exploited in a 'rapid-analysis' method in which a crude organic extract of similar to 2 x 10(9) L. major promastigote cells was loaded onto a reverse-phase cartridge for immediate elution into the mass-spectrometer. Using this approach, it was possible to identify the repeating units by total ion scanning and scanning for parents of the m/z 79 (PO3-) fragment ion. This approach is suitable for quick-typing of lipophosphoglycan repeats and was shown to detect alterations in repeat side chains caused by: (1) culturing L. major promastigotes in the presence of L-fucose; and (2) in vitro metacyclogenesis of L. major promastigotes. It is anticipated that the method will be applicable to small samples of cultured field isolates or genetically-manipulated strains. (C) 1999 Elsevier Science B.V. All rights reserved.
|Number of pages||9|
|Journal||Molecular and Biochemical Parasitology|
|Publication status||Published - 25 May 1999|