Time of flight versus ion trap MS coupled to CE to analyse intact proteins

Abstract

In this work, two different CE-MS instruments, namely, CE-ESI-IT-MS and CE-ESI-TOF-MS, applied to analyse intact proteins from complex samples are investigated. The aim of this work was to compare both instruments in terms of LOD, number of proteins detected, and precision and repeatability in the determination of the protein relative molecular mass. Results show that although CE-ESI-IT-MS provides cleaner MS spectra of intact proteins, CE-ESI-TOF-MS allows the identification of a higher number of proteins from complex matrices in an easier way. Performance in terms of peak area reproducibility, LOD and precision in the determination of the molecular mass were similar for both instruments. The usefulness of the optimised CE-ESI-IT-MS and CE-ESI-TOF-MS conditions was demonstrated by studying the zein-proteins composition of three natural maize lines and their corresponding transgenic lines, showing no significant differences.

Modification of Resolution in Capillary Electrophoresis for Protein Profiling in Identification of Genetic Modification in Foods

“…20 In the earlier work, in similar conditions of extraction and electrophoretic separation with MS detection, there were also not observed any significant differences in terms of zein content between non-transgenic and transgenic variants. However some differences were observed between different lines of conventional maize.…”

“…[14][15][16] Recently, there were several attempts to employ CE to obtain the protein profiles in extracts of maize and soybean, oriented towards finding some differences between genetically modified plant material or foods and natural variants and their food products. For this purpose both CE measurements with UV 17,18 and MS detections 19,20 were reported. Such studies were carried out for maize samples, [18][19][20] as well soybean, 17 of which GM variants are most commonly cultivated.…”

“…For this purpose both CE measurements with UV 17,18 and MS detections 19,20 were reported. Such studies were carried out for maize samples, [18][19][20] as well soybean, 17 of which GM variants are most commonly cultivated. It is well known that applied conditions of solvent extraction from plant material allow to extract different types of proteins.…”

“…The extraction in investigation of maize samples was carried out with mixture of acetonitrile (ACN) and water with addition of 2-mercapto-ethanol (ME) and ammonia. 19,20 For this purpose also watersoluble fraction (albumins) was used, 18 while in case of soybean extracts the fraction extracted with ACN/water mixture with acetic acid. 17 The CE measure-ments with UV detection were carried out using capillaries without any modification with borate back-ground electrolyte (BGE) with ACN addition for proteins extracted with ACN/water with acetic acid, 17 while in case of albumins extracted with water several acidic BGEs were examined, assuming 0.2 mol dm −3 solution of iminodiactetic acid of pH 2.26 was the optimum.…”

“…17 The CE measure-ments with UV detection were carried out using capillaries without any modification with borate back-ground electrolyte (BGE) with ACN addition for proteins extracted with ACN/water with acetic acid, 17 while in case of albumins extracted with water several acidic BGEs were examined, assuming 0.2 mol dm −3 solution of iminodiactetic acid of pH 2.26 was the optimum. 18 For CE determination of zeins with MS detection the capillary was modified with ethylpyrrolidine methacrylate-N,N-dimethylacrylamide, 19,20 and in both these cases BGE used was a mixture of ACN, isopropanol, formic acid and water.…”