Polyethylene Membrane as a Sample Support for Direct Matrix-Assisted Laser Desorption/Ionization Mass Spectrometric Analysis of High Mass Proteins

Abstract

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) of high mass proteins (> 100,000 Da), directly deposited on polyethylene membranes, is demonstrated. The spectral quality obtained, using standard sample preparation conditions, is equal or superior to that obtained with metal sample stages. Compared to the use of poly(vinylidene difluoride) transfer membranes, this material allows the acquisition of excellent quality MALDI mass spectra from high-mass proteins with a standard UV laser. This gain in capability is not at the expense of either mass accuracy or signal reproducibility; both approach that obtained with standard sample preparations on stainless steel. In addition, for the applications shown, the use of PE as a sample support reduces the severe ion suppression effects typically observed in the MALDI analysis of high-mass mixtures. This permits more precise mass measurements to be made via the use of internal calibration and is illustrated by the mass measurement of a chimeric mouse/human antibody (MW approximately 150,000 Da) by coaddition of bovine albumin dimer (MW approximately 130,000 Da).

Matrix-assisted laser desorption ionization mass spectrometry detection of proteins adsorbedin vivo onto contact lenses

“…Porous polymer substrates were previously used to improve the intensity of MALDI signals in protein detection. 15 However, our use of MALDI-MS differs in that it probes for proteins that are tightly, irreversibly adsorbed on solid surfaces rather than solubilized in aqueous solution inside a porous polymer matrix.…”

New directions of miniaturization within the proteomics research area

“…This is especially applicable within studies where 2-D gels and LC-fractions are being analyzed. To improve detection levels in protein research, affinity-based purification techniques to enrich and purify samples is a widely used technology [42][43][44][45]. Solid-phase extraction (SPE) based on hydrophobic/hydrophilic interaction is used as a standard in protein research today and pipette tips loaded with, e.g., C18-activated microbeads for this purpose are commercially available by several suppliers.…”

“…Sample preparation of proteins spots derived from 2-D gels, 1-D gels or gel-free systems, i.e., liquid chromatography fractions, often uses some type of enrichment step, e.g., solid-phase extraction principles [12,13]. The ability to probe differential expression analysis of proteins is still the ultimate goal of most proteomics activities of today.…”

Sample preparation for analysis by MALDI-TOF Mass Spectrometry

“…Le transfert (ou le dépôt) de protéines sur divers types de membranes et la désorption de ces protéines directement dans la source du spectromètre sont bien documentés (polyéthylène [7], PVDF [8], NC [9,10] [14]. Une étude récente a permis de montrer que l'on pouvait faire de la chromatographie à basse pression sur 0,3 µL de phase et en présence de différentes matrices (DHB, AS, ACHCA) [15].…”