K. Linnemayr et al., COMPARISON OF MICROSCALE CLEANING PROCEDURES FOR (GLYCO) PROTEINS PRIOR TO POSITIVE-ION MATRIX-ASSISTED LASER-DESORPTION IONIZATION MASS-SPECTROMETRY, Analytica chimica acta, 372(1-2), 1998, pp. 187-199
Microscale cleaning procedures for peptides, proteins and glycoprotein
s prior to matrix-assisted laser desorption ionization (MALDI) mass sp
ectrometric (MS) analysis, based on different mechanisms - drop dialys
is, ultrafiltration, reverse phase adsorption and gelfiltration, are b
eing compared. The selected standard (glyco) proteins cover the mass r
ange of 5000-70 000 Da. Individual components and mixtures containing
up to five components have been used for the investigation. Five diffe
rent procedures were applied and evaluated with regard to a subsequent
positive ion MALDI time-of-flight MS analysis, which requires samples
with relative low salt/buffer content. All methods were adapted for p
rotein samples in the low picomole range. Drop dialysis, ultrafiltrati
on, reverse phase adsorption in two different forms and gelfiltration
are shown to be useful for proteins and partially for peptides and gly
coproteins. It turned out that glycoproteins are more difficult to han
dle, due to the relatively high sample losses during the desalting pro
cedures. Gelfiltration and reverse phase adsorption are the least time
consuming methods, whereas drop dialysis and ultrafiltration are well
suited for working on many samples in parallel. However, reverse phas
e adsorption and ultrafiltration offer the highest enrichment factors.
For proteins available only in large sample volumes gelfiltration and
reverse phase adsorption are the methods of choice. (C) 1998 Elsevier
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