Capillary-Scale Frontal Affinity Chromatography/MALDI Tandem Mass Spectrometry Using Protein-Doped Monolithic Silica Columns
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- 作者：Peter Kovarik ; Richard J. Hodgson ; Tom Covey ; Michael A. Brook ; and John D. Brennan
- 刊名：Analytical Chemistry
- 出版年：2005
- 出版时间：May 15, 2005
- 年：2005
- 卷：77
- 期：10
- 页码：3340 - 3350
- 全文大小：369K
- 年卷期：v.77,no.10(May 15, 2005)
- ISSN：1520-6882
文摘
Frontal affinity chromatography (FAC) interfaced withelectrospray mass spectrometry (ESI-MS) has been reported as a potential method for screening of compoundmixtures against immobilized target proteins. However,the interfacing of bioaffinity columns to ESI-MS requiresthat the eluent that passes through the protein-loadedcolumn have a relatively low ionic strength to produce astable spray. Such low ionic strength solvents can causeserious problems with protein stability and may also affectbinding constants and lead to high nonspecific bindingto the column. Herein, we report on the interfacing ofbioaffinity columns to matrix-assisted laser desorption/ionization (MALDI) MS/MS as a new platform for FAC/MS studies. Capillary columns containing a monolithicsilica material with entrapped dihydrofolate reductasewere used for frontal affinity chromatography of small-molecule mixtures. The output from the column wascombined with a second stream containing 
-cyano-hydoxycinnamic acid in methanol and was depositedusing a nebulizer-assisted electrospray method onto aconventional MALDI plate that moved relative to thecolumn via a computer-controlled x-y stage, creating asemipermanent record of the FAC run. The use of MALDIMS/MS allowed for buffers with significantly higher ionicstrength to be used for FAC studies, which reducednonspecific binding of ionic compounds and allowed forbetter retention of protein activity over multiple runs.Following deposition, MALDI analysis required only afraction of the chromatographic run time, and the deposited track could be rerun multiple times to optimizeionization parameters and allow signal averaging to improve the signal-to-noise ratio. Furthermore, high levelsof potential inhibitors could be detected via MALDI withlimited ion suppression effects. Both MALDI- and ESI-based analysis showed similar retention of inhibitorspresent in compound mixtures when using identical ionicstrength conditions. The results show that FAC/MALDI-MS should provide advantages over FAC/ESI-MS for high-throughput screening of compound mixtures.
-cyano-hydoxycinnamic acid in methanol and was depositedusing a nebulizer-assisted electrospray method onto aconventional MALDI plate that moved relative to thecolumn via a computer-controlled x-y stage, creating asemipermanent record of the FAC run. The use of MALDIMS/MS allowed for buffers with significantly higher ionicstrength to be used for FAC studies, which reducednonspecific binding of ionic compounds and allowed forbetter retention of protein activity over multiple runs.Following deposition, MALDI analysis required only afraction of the chromatographic run time, and the deposited track could be rerun multiple times to optimizeionization parameters and allow signal averaging to improve the signal-to-noise ratio. Furthermore, high levelsof potential inhibitors could be detected via MALDI withlimited ion suppression effects. Both MALDI- and ESI-based analysis showed similar retention of inhibitorspresent in compound mixtures when using identical ionicstrength conditions. The results show that FAC/MALDI-MS should provide advantages over FAC/ESI-MS for high-throughput screening of compound mixtures.