UV-MALDI-TOF-MS Analysis of NBD-Glycosphingolipids without an EXTERNAL PHOTOSENZITIZER

MALENA LANDONI,; VILMA DUSCHAK; ROSA ERRA-BALSELLS; ALICIA S. COUTO; ERRA BALSELLS, ROSA

Universidad Austral, Pilar, Buenos Aires, del 27 al 30 de junio del 2007,

Congreso; Primer Congreso Iberoamericano de Proteómica,; 2007

LAHUPO, la recientemente creada filial latinoamericana de Human Proteome Organization (HUPO).

UV-MALDI-TOF-MS ANALYSIS OF NBD-GLYCOSPHINGOLIPIDS without an external photosenzitizer. Malena Landoni1, Vilma Duschak2, Rosa Erra-Balsells1 and Alicia S. Couto1 1CIHIDECAR, Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Bs As, 1428, Argentina. 2 Departamento de Investigación, Inst. Nac. de Parasitología ?Dr Mario Fatala Chaben?, ANLIS-Malbrán, Ministerio de Salud, Bs As, Argentina. Following an explosive growth in genomics and proteomics, glycomics focuses on the role of carbohydrates in biological systems and is used to define the interactions of carbohydrates with oligonucleotides, lipids and proteins. Today, UV-MALDI time-of-flight mass spectrometry is perhaps the most important mass spectroscopic technique currently used for glycoconjugate analysis.  However, one of the most difficult parts in MALDI analysis seems to be the sample preparation, since this step is crucial for the success of the MALDI experiment. Even if recent years have provided much deeper insights into the general MALDI process, it is in some cases still relatively unclear (apart from the straightforward observation that a matrix has to absorb light at the laser wavelength) why certain molecules can act as matrices and others not or, in other words, how to optimize or choose a matrix?s chemical structure in such a way as to obtain better results for the analysis of otherwise difficult analytes. In addition, application of matrix-assisted laser-desorption ionization mass spectrometry to small-molecule detection is often limited, because of high matrix background signals in the low-mass region. On the other hand, perhaps the greatest advance in tagging methods for biochemical profiling has been the use of small molecule fluorophores.  Some of the most significant advantages of fluorophores are their use for direct imaging of labeled targets using fluorescence microscopy as well as their ease of detection in SDS-PAGE gels and TLCs using a laser scanner. Furthermore, these fluorescent tags are hydrophobic and freely penetrate cell membranes. We report here an approach in which UV-MALDI-TOF-MS analysis of glycosphingolipids has been performed using a fluorescent  tag linked to the sphingoid base who works as UV-MALDI matrix. The goal of this work is to show that no matrix needs to be added for the UV-MALDI-TOF-MS analysis as the same tag used to metabolically label the lipids may generate radical cations or intramolecular excited-state proton-transfer reactions allowing the obtention of high quality spectra. The selective detection of the analyte molecules provides an opportunity to simplify biological sample profiling and adds a new use for these type of compounds as matrix in UV-MALDI mass analysis.