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Alkylation power of free Immobiline chemicals towards proteins in isoelectric focusing and two‐dimensional maps, as explored by matrix assisted laser desorption/ionization‐time of flight‐mass spectrometry
Author(s) -
Bordini Ellenia,
Hamdan Mahmoud,
Righetti Pier Giorgio
Publication year - 2000
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(20000801)21:14<2911::aid-elps2911>3.0.co;2-s
Subject(s) - mass spectrometry , isoelectric focusing , desorption , chemistry , ionization , time of flight mass spectrometry , chromatography , matrix (chemical analysis) , matrix assisted laser desorption/ionization , laser , analytical chemistry (journal) , organic chemistry , physics , ion , optics , enzyme , adsorption
A number of Immobilines, with p K 1.0—10.3, were incubated with two proteins, bovine α‐lactalbumin (p I 4.80) and chicken egg lysozyme (p I 9.32), at pH ˜ 9—10 and the resulting solutions were examined by matrix assisted laser desorption/ionization — mass spectrometry. The reflectron mode of the same technique was also used to analyze a number of tryptic digests of some solutions. The extent and the number of detected alkylation sites associated with the acidic protein were found to be linearly proportional to the p K values of the investigated Immobilines, an effect which was less evident for the basic protein. The high resolution measurements of some tryptic digests indicate the cysteine residues as the likely sites of alkylation. The implications of the present data for isoelectric focusing separations on immobilized pH gradients and for two‐dimensional maps are discussed.