Decrease of serum protein concentration difference by solid-phase ligand libraries

Objective: To determine the effects of solid-phase ligand libraries on enrichment of low-abundance serum protein and improve the low-abundance serum protein identification by mass spectrometer(MS). Methods: Three pooled serum samples were treated with ProteoMiner and then subjected to one-dimensional (one-D) or two-dimensional (two-D) SDS-PAGE followed by comparative image analysis. The remarkable increased protein spots on two-D map were identified by high performance liquid chromatogrphy ( HPLC ) coupled on-line to ESI/MS-MS. Results: The one-D and two-D gel map revealed more low-abundance protein bands and protein spots, respectively. MS identification of significantly enriched protein spots on two-D gel improved low-abundance protein identification after library beads treatment, e. g. clusterin, vitronectin, C4b-binding protein alpha chain, complement C4-A. Conclusion: The technique of solid-phase ligand libraries can enrich serum low-abundance proteins whilst decrease high-abundance protein concentration, which indicates that this method is useful for enrichment of low-abundance protein and identification.