Premium
Towards a reliable molecular mass determination of intact glycoproteins by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Author(s) -
Giménez Estela,
Benavente Fernando,
Barbosa José,
SanzNebot Victoria
Publication year - 2007
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3109
Subject(s) - chemistry , mass spectrometry , molecular mass , chromatography , glycoprotein , matrix assisted laser desorption/ionization , fetuin , matrix (chemical analysis) , fragmentation (computing) , time of flight mass spectrometry , desorption , analytical chemistry (journal) , mass spectrum , surface enhanced laser desorption/ionization , glycosylation , ionization , protein mass spectrometry , biochemistry , ion , electrospray ionization , organic chemistry , adsorption , computer science , enzyme , operating system
Different matrices and sample‐matrix preparation procedures have been tested in order to study their influence on the matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectra of intact glycoproteins, which present different degrees of glycosylation (human transferrin; bovine fetuin; bovine α 1 ‐acid‐glycoprotein; recombinant human erythropoietin; and the novel erythropoiesis stimulating protein). Using sinapinic acid (SA) and the fast evaporation method, the studied glycoproteins became susceptible to fragmentation at any laser intensity, suggesting that this ‘hot’ matrix is unsuitable for a reliable molecular mass determination of glycosylated compounds. In contrast, 2,5‐dihydroxybenzoic acid (DHB) and 6‐aza‐2‐thiothymine (ATT), with an adequate sample‐matrix preparation, provided improved results. Samples containing DHB after crystallization by vacuum drying demonstrated the best performance because the labile functional groups from the glycoforms were apparently fragmented to a lower extent. The average molecular masses obtained using this methodology were in all cases a better estimation than those values reported in the literature. The results were reproducible, and sensitivity was similar to that obtained with SA and the fast evaporation method. These excellent results suggest that this MALDI‐TOF‐MS methodology could be useful for an improved determination of the average molecular mass values of microheterogeneous compounds such as glycoproteins, glycosylated compounds or, in general, molecular mass values of molecules with similar labile functional groups. Copyright © 2007 John Wiley & Sons, Ltd.