Submicrometer Particles for Better Protein LC in Top-Down Proteomics

Mary J. Wirth, Department of Chemistry, Purdue University, IN, USA
Ximo Zhang, Department Of Chemistry, Purdue University, In, Usa
Neil Kelleher , Northwestern University, Il, Usa
Phil Compton, Northwestern University, Il, Usa

Capillaries packed with nonporous 0.5 um silica particles are used for LCMS of intact histones. These particles give more efficient protein separations than the conventional micro-scale particles due to faster mass transport. These particles also provide comparable accessible surface area compared to conventional wide-pore silica particles. Slip flow, owing to the nanoscale interparticle dimensions,  enables high flow rates for stable electrospray and fast protein analyses. Capillaries of typically 4 to 5 cm in length exhibit high resolution of histones, which are the proteins that spool DNA into chromosomes. Post-translational modifications of histones are known to control gene expression dynamically, and this process malfunctions in diseases. Better resolution of histones by these efficient capillaries enables a fuller characterization of histone variants by mass spectrometry.