Mouse-specific tandem IgY7-SuperMix immunoaffinity separations for improved LC-MS/MS coverage of the plasma proteome.

We report on a mouse specific SuperMix immunoaffinity separation system for separating low-abundance proteins from high and moderate abundance proteins in mouse plasma. When applied in tandem with a mouse IgY7 column that removes the seven most abundant proteins in plasma, the SuperMix column captures more than 100 additional moderate abundance proteins, thus allowing significant enrichment of low-abundance proteins in the flow-through fraction. A side-by-side comparison of results obtained from 2D-LC-MS/MS analyses of flow-through samples from IgY7 and SuperMix columns revealed a nearly 2-fold improvement in the overall proteome coverage. Detection of low-abundance proteins was also enhanced, as evidenced by a more than 2-fold increase in the coverage of cytokines, growth factors, and other low-abundance proteins. Moreover, the tandem separations are automated, reproducible, and allow effective identification of protein abundance differences from LC-MS/MS analyses. Considering the overall reproducibility and increased sensitivity using the IgY7-SuperMix separation system, we anticipate broad applications of this strategy for biomarker discovery using mouse models.